Patent Publication Number: US-11399197-B2

Title: Encoding device and encoding method with setting and encoding of reference information

Description:
This application is a continuation of U.S. patent application Ser. No. 16/243,040 filed Jan. 8, 2019 (U.S. Pat. No. 10,958,930), which is a continuation of U.S. patent application Ser. No. 14/402,544 filed Nov. 20, 2014 (U.S. Pat. No. 10,623,765), which is the national phase of PCT Application PCT/JP2013/067112 filed Jun. 21, 2013, which claims priority of Japanese Application JP 2012-147883 filed Jun. 29, 2012 and Japanese Application JP 2012-218097 filed Sep. 28, 2012, the entire contents of each of which is incorporated herein by reference 
    
    
     TECHNICAL FIELD 
     The present technology relates to an encoding device and an encoding method and, more particularly, to an encoding device and an encoding method capable of reducing the amount of information relating to information that specifies a reference image. 
     BACKGROUND ART 
     Recently, image information is handled as digital data, and, for the purpose of transmission and storage of information having high-efficiency at that time, devices that are in compliance with the MPEG (Moving Picture Experts Group phase) system or the like that performs an orthogonal transform such as a discrete cosine transform and compression using motion compensation, by using the redundancy that is unique to the image information, are widely used for both information delivery in broadcasting stations and the like and information reception in standard homes. 
     Particularly, the MPEG2 (ISO/IEC 13818-2) system is defined as a general-purpose image coding system and is currently used widely for a broad range of applications for the professional use and the consumer use as standards covering both an interlaced scanning image and a sequential scanning image and a standard resolution image and a high definition image. By using the MPEG2 system, for example, a code amount (bit rate) of 4 to 8 Mbps in the case of an interlaced scanning image of a standard resolution of 720.times.480 pixels and a code amount of 18 to 22 Mbps in the case of an interlaced scanning image of high definition of 1920.times.1088 pixels are allocated, whereby a high compression rate and an improved image quality can be realized. 
     MPEG2 is targeted for high image quality coding that is mainly suitable for broadcasting but does not respond to a coding system of a code amount (bit rate) lower than that of MPEG1, in other words, a coding system of a higher compression rate. In accordance with the popularization of mobile terminals, the request for such a coding system is predicted to increase in the future, and an MPEG4 coding system has been standardized in response thereto. Relating to the image coding system of MPEG4, a specification has been approved in December, 1998 to be an international standard as ISO/IEC 14496-2. 
     In addition, recently, for the purpose of image coding used for television conferences, the standardization of H.26L (ITU-T Q6/16 VCEG) is in the progress. While H.26L requires the amount of calculation according to coding and decoding that is larger than that of a conventional coding system such as MPEG2 or MPEG4, it is known that a higher coding efficiency is realized. 
     Furthermore, currently, as part of activities of MPEG4, the standardization of a specification, which is based on H.26L, including functions not supported in H.26L and realizing higher coding efficiency is in the process as Joint Model of Enhanced-Compression Video Coding. This standardization is internationally standardized based on the title of H.264 and MPEG-4 Part 10 (AVC (Advanced Video Coding)) in March, 2003. 
     In addition, the standardization of FRExt (Fidelity Range Extension) including, as extensions, a coding tool, which is required for a business, called RGB, 4:2:2 or 4:4:4 and 8.times.8 DCT and a quantization matrix defined in MPEG-2 has been completed in February, 2005. Accordingly, the AVC becomes a coding system capable of representing a film noise included in a movie in an improved manner as well and is a system in which it is used for a broad range of applications such as a Blu-Ray (registered trademark) Disc. 
     However, in these days, the request for higher-compression-rate coding required for compressing an image of about 4000.times.2000 pixels, which are four times those of a high vision image, and for delivering the high vision image in a limited transmission capacity environment such as the Internet has been increased. For this reason, in a VCEG (Video Coding Expert Group) under the ITU-T, reviews for improving the coding efficiency have been continuously performed. 
     Meanwhile, in an HEVC (High Efficiency Video Coding) system, a short-term reference picture set (hereinafter, referred to as an RPS) used for recognizing reference image specifying information that specifies a reference image in a decoding device is included in an SPS (Sequence Parameter Set) (for example, see Non-Patent Document 1). 
       FIG. 1  is a diagram that illustrates an example of the syntax of an RPS. 
     As illustrated in the second line in  FIG. 1 , in the RPS, inter_ref_pic_set_prediction_flag is included. Here, inter_ref_pic_set_prediction_flag is reference information that represents whether reference image specifying information that specifies a reference image of a prior image, which is an image prior to a current coding image in coding order within a GOP (Group of Picture) of the current coding image, is used as reference image specifying information of the current coding image. 
     Here, inter_ref_pic_set_prediction_flag is “1” in a case where it represents that the reference image specifying information specifying the reference image of the prior image is used as the reference image specifying information of the current coding image and is “0” in a case where it represents that the reference image specifying information specifying the reference image of the prior image is not used as the reference image specifying information of the current coding image. 
     As the third and fourth lines in  FIG. 1 , in a case where inter_ref_pic_set_prediction_flag is “1”, delta_idx_minus1 that is the prior image specifying information specifying the prior image is included in the RPS. More specifically, delta_idx_minus1 has a value acquired by subtracting one from a value that is acquired by subtracting the coding number of the prior image from the coding number (coding order) of the current coding image. Here, the coding number is a number that is assigned to each image within the GOP from a small value in order of coding. 
     In addition, as illustrated in the 13th to 23rd lines in  FIG. 1 , in a case where inter_ref_pic_set_prediction_flag is “0”, the reference image specifying information is included in the RPS. 
       FIG. 2  is a diagram that illustrates an example of inter_ref_pic_set_prediction_flag and delta_idx_minus1. 
     In the example illustrated in  FIG. 2 , the reference image specifying information of the current coding image of which the coding number is N is the same as the reference image specifying information of the prior image, of which the coding number is “N−1”, that is prior to the current coding image in coding order. 
     In this case, inter_ref_pic_set_prediction_flag is set to “1” that represents the reference image specifying information of the prior image is used as the reference image specifying information of the current coding image. In addition, delta_idx_minus1 is set to “0” that is acquired by subtracting “N−1” that is the coding number of the prior image from N that is the coding number of the current coding image and then, from a value of “1” that is acquired as a result of the subtraction, additionally subtracting one. 
     CITATION LIST 
     Non-Patent Document 
     
         
         Non-Patent Document 1: Benjamin Bross, Woo-Jin Han, Jens-Rainer Ohm, Gary J. Sullivan, Thomas Wiegand, “High efficiency video coding (HEVC) text specification draft 7”, JCTVC-I1003_d4, 2012.4.27-5.7 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, the amount of information relating to the reference image specifying information such as the RPS is not sufficiently reduced. 
     The present technology is contrived in consideration of such a situation and enables reduction of the amount of information relating to the information that specifies a reference image. 
     Solutions to Problems 
     According to an aspect of the present technology, there is provided an encoding device including: a predicted image generation unit configured to generate a predicted image using a reference image; and a transmission unit configured to transmit reference information representing whether reference image specifying information specifying the reference image of a prior image that is an image prior to a current coding image in coding order is used as the reference image specifying information of the current coding image in a case where the current coding image is an image other than a first image of a GOP (Group of Picture). 
     An encoding method according to another aspect of the present technology corresponds to the encoding device according to the aspect of the present technology. 
     According to the aspect of the present technology, a predicted image is generated using a reference image; and reference information representing whether reference image specifying information specifying the reference image of a prior image that is an image prior to a current coding image in coding order is used as the reference image specifying information of the current coding image is transmitted in a case where the current coding image is an image other than a first image of a GOP (Group of Picture). 
     In addition, the encoding device according to the aspect of the present technology may be realized by causing a computer to execute a program. 
     Furthermore, in order to realize the encoding device according to the aspect of the present technology, the program executed by the computer may be provided by being transmitted through a transmission medium or being recorded on a recording medium. 
     Effects of the Invention 
     According to the present technology, the amount of information relating to information that specifies a reference image can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram that illustrates an example of the syntax of an RPS. 
         FIG. 2  is a diagram that illustrates an example of inter_ref_pic_set_prediction_flag and delta_idx_minus1. 
         FIG. 3  is a block diagram that illustrates an example of the configuration of an encoding device, to which the present technology is applied, according to a first embodiment. 
         FIG. 4  is a block diagram that illustrates an example of the configuration of an encoding unit illustrated in  FIG. 3 . 
         FIG. 5  is a diagram that illustrates an example of the syntax of an SPS that is set by a setting unit  12  illustrated in  FIG. 3 . 
         FIG. 6  is a diagram that illustrates an example of the syntax of an RPS. 
         FIG. 7  is a diagram that illustrates the information amount of the RPS that is set by the setting unit  12  illustrated in  FIG. 3 . 
         FIG. 8  is a diagram that illustrates the information amount of a conventional RPS. 
         FIG. 9  is a diagram that illustrates an example of the syntax of a slice header. 
         FIG. 10  is a flowchart that illustrates a generation process performed by the encoding device illustrated in  FIG. 3 . 
         FIG. 11  is a flowchart that illustrates an RPS setting process illustrated in  FIG. 10  in detail. 
         FIG. 12  is a flowchart that illustrates a coding process illustrated in  FIG. 10  in detail. 
         FIG. 13  is a flowchart that illustrates the coding process illustrated in  FIG. 10  in detail. 
         FIG. 14  is a flowchart that illustrates an RPS index determining process illustrated in  FIG. 12  in detail. 
         FIG. 15  is a block diagram that illustrates an example of the configuration of a decoding device, to which the present technology is applied, according to the first embodiment. 
         FIG. 16  is a block diagram that illustrates an example of the configuration of a decoding unit illustrated in  FIG. 15 . 
         FIG. 17  is a flowchart that illustrates a reception process performed by the decoding device illustrated in  FIG. 15 . 
         FIG. 18  is a flowchart that illustrates an RPS setting process illustrated in  FIG. 17  in detail. 
         FIG. 19  is a flowchart that illustrates a decoding process illustrated in  FIG. 17  in detail. 
         FIG. 20  is a block diagram that illustrates an example of the configuration of an encoding device, to which the present technology is applied, according to a second embodiment. 
         FIG. 21  is a diagram that illustrates an example of the syntax of an SPS that is set by a setting unit illustrated in  FIG. 20 . 
         FIG. 22  is a diagram that illustrates an example of the syntax of an RPS illustrated in  FIG. 21 . 
         FIG. 23  is a diagram that illustrates the information amount of the RPS that is set by the setting unit illustrated in  FIG. 20 . 
         FIG. 24  is a diagram that illustrates the information amount of the RPS that is set by the setting unit illustrated in  FIG. 20 . 
         FIG. 25  is a diagram that illustrates the information amount of a conventional RPS. 
         FIG. 26  is a flowchart that illustrates an RPS setting process performed by the encoding device illustrated in  FIG. 20  in detail. 
         FIG. 27  is a block diagram that illustrates an example of the configuration of a decoding device, to which the present technology is applied, according to the second embodiment. 
         FIG. 28  is a flowchart that illustrates an RPS setting process performed by the decoding device illustrated in  FIG. 27  in detail. 
         FIG. 29  is a block diagram that illustrates an example of the configuration of an encoding device, to which the present technology is applied, according to a third embodiment. 
         FIG. 30  is a diagram that illustrates an example of the syntax of an SPS that is set by a setting unit illustrated in  FIG. 29 . 
         FIG. 31  is a diagram that illustrates an example of the syntax of an RPS illustrated in  FIG. 30 . 
         FIG. 32  is a diagram that illustrates the information amount of the RPS that is set by the setting unit illustrated in  FIG. 29 . 
         FIG. 33  is a flowchart that illustrates an RPS setting process performed by the encoding device illustrated in  FIG. 29  in detail. 
         FIG. 34  is a block diagram that illustrates an example of the configuration of a decoding device, to which the present technology is applied, according to the third embodiment. 
         FIG. 35  is a flowchart that illustrates an RPS setting process performed by the decoding device illustrated in  FIG. 34  in detail. 
         FIG. 36  is a block diagram that illustrates an example of the configuration of an encoding device, to which the present technology is applied, according to a fourth embodiment. 
         FIG. 37  is a block diagram that illustrates an example of the configuration of an encoding unit illustrated in  FIG. 36 . 
         FIG. 38  is a diagram that illustrates an example of the syntax of a PPS that is set by a setting unit illustrated in  FIG. 36 . 
         FIG. 39  is a diagram that illustrates an example of the syntax of the PPS that is set by the setting unit illustrated in  FIG. 36 . 
         FIG. 40  is a diagram that illustrates an example of the syntax of a PPS in a conventional HEVC system. 
         FIG. 41  is a diagram that illustrates an example of the syntax of a PPS in a conventional HEVC system. 
         FIG. 42  is a diagram that illustrates an example of the syntax of a slice header that is added by a lossless encoding unit illustrated in  FIG. 37 . 
         FIG. 43  is a diagram that illustrates an example of the syntax of the slice header that is added by the lossless encoding unit illustrated in  FIG. 37 . 
         FIG. 44  is a diagram that illustrates an example of the syntax of the slice header that is added by the lossless encoding unit illustrated in  FIG. 37 . 
         FIG. 45  is a diagram that illustrates an example of the syntax of a slice header in a conventional HEVC system. 
         FIG. 46  is a diagram that illustrates an example of the syntax of a slice header in a conventional HEVC system. 
         FIG. 47  is a diagram that illustrates an example of the syntax of a slice header in a conventional HEVC system. 
         FIG. 48  is a flowchart that illustrates a generation process performed by the encoding device illustrated in  FIG. 36 . 
         FIG. 49  is a flowchart that illustrates a coding process illustrated in  FIG. 48  in detail. 
         FIG. 50  is a flowchart that illustrates the coding process illustrated in  FIG. 48  in detail. 
         FIG. 51  is a flowchart that illustrates a PPS setting process illustrated in  FIG. 48  in detail. 
         FIG. 52  is a block diagram that illustrates an example of the configuration of a decoding device, to which the present technology is applied, according to a fourth embodiment. 
         FIG. 53  is a block diagram that illustrates an example of the configuration of a decoding unit illustrated in  FIG. 52 . 
         FIG. 54  is a flowchart that illustrates a reception process performed by the decoding device illustrated in  FIG. 52 . 
         FIG. 55  is a flowchart that illustrates a decoding process illustrated in  FIG. 54  in detail. 
         FIG. 56  is a diagram that illustrates an example of a multiple viewpoint image coding system. 
         FIG. 57  is a diagram that illustrates an example of the main configuration of a multiple viewpoint image encoding device to which the present technology is applied. 
         FIG. 58  is a diagram that illustrates an example of the main configuration of a multiple viewpoint image decoding device to which the present technology is applied. 
         FIG. 59  is a diagram that illustrates an example of a hierarchical image coding system. 
         FIG. 60  is a diagram that illustrates an example of the main configuration of a hierarchical image encoding device to which the present technology is applied. 
         FIG. 61  is a diagram that illustrates an example of the main configuration of a hierarchical image decoding device to which the present technology is applied. 
         FIG. 62  is a block diagram that illustrates an example of the hardware configuration of a computer. 
         FIG. 63  is a diagram that illustrates an example of the schematic configuration of a television apparatus to which the present technology is applied. 
         FIG. 64  is a diagram that illustrates an example of the schematic configuration of a mobile phone to which the present technology is applied. 
         FIG. 65  is a diagram that illustrates an example of the schematic configuration of a recording and reproducing device to which the present technology is applied. 
         FIG. 66  is a diagram that illustrates an example of the schematic configuration of an imaging device to which the present technology is applied. 
         FIG. 67  is a block diagram that illustrates an example of the use of scalable coding. 
         FIG. 68  is a block diagram that illustrates another example of the use of the scalable coding. 
         FIG. 69  is a block diagram that illustrates a further another example of the use of the scalable coding. 
         FIG. 70  is a diagram that illustrates an example of the schematic configuration of a video set to which the present technology is applied. 
         FIG. 71  is a diagram that illustrates an example of the schematic configuration of a video processor to which the present technology is applied. 
         FIG. 72  is a diagram that illustrates another example of the schematic configuration of a video processor to which the present technology is applied. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     First Embodiment 
     (Configuration Example of Encoding Device According to First Embodiment) 
       FIG. 3  is a block diagram that illustrates an example of the configuration of an encoding device, to which the present technology is applied, according to the first embodiment. 
     An encoding device  10  illustrated in  FIG. 3  is configured by an encoding unit  11 , a setting unit  12 , and a transmission unit  13  and encodes an image in accordance with an HEVC system. 
     More specifically, an image that is configured in units of frames is input to the encoding unit  11  of the encoding device  10  as an input signal. The encoding unit  11  codes the input signal in accordance with the HEVC system by referring to an RPS that is supplied from the setting unit  12  and supplies coded data acquired as a result thereof to the setting unit  12 . 
     The setting unit  12  sets an RPS that does not include inter_ref_pic_set_prediction_flag but includes the reference image specifying information and an RPS that includes inter_ref_pic_set_prediction_flag and the reference image specifying information or delta_idx_minus1. To each RPS, the setting unit  12  assigns an index as reference image information specifying information that specifies the RPS (reference image information). Here, it is assumed that “0” is set as an index of the RPS that does not include inter_ref_pic_set_prediction_flag but includes the reference image specifying information. 
     The setting unit  12  supplies the RPS to which the index has been assigned to the encoding unit  11 . The setting unit  12  sets an SPS including the RPS, a PPS (Picture Parameter Set), and the like. 
     The setting unit  12  generates a coded stream based on the SPS and the PPS, which have been set and coded data supplied from the encoding unit  11 . The setting unit  12  supplies the coded stream to the transmission unit  13 . 
     The transmission unit  13  transmits the coded stream supplied from the setting unit  12  to as a decoding device to be described later. 
     (Configuration Example of Encoding Unit) 
       FIG. 4  is a block diagram that illustrates an example of the configuration of the encoding unit  11  illustrated in  FIG. 3 . 
     The encoding unit  11  illustrated in  FIG. 4  includes: an A/D converter  31 ; a screen rearrangement buffer  32 ; a calculation unit  33 ; an orthogonal transform unit  34 ; an quantization unit  35 ; a lossless encoding unit  36 ; an accumulation buffer  37 ; an inverse quantization unit  38 ; an inverse orthogonal transform unit  39 ; an addition unit  40 ; a deblocking filter  41 , an adaptive offset filter  42 ; an adaptive loop filter  43 ; a frame memory  44 ; a switch  45 ; an intra prediction unit  46 ; a motion prediction/compensation unit  47 ; a predicted image selection unit  48 ; a reference image setting unit  49 ; and a rate control unit  50 . 
     More specifically, the A/D converter  31  of the encoding unit  11  performs A/D conversion of an image, which is in units of frames, that is input as an input signal and outputs the converted image to the screen rearrangement buffer  32  so as to be stored therein. The screen rearrangement buffer  32  rearranges stored images, which are in units of frames, that are in display order in accordance with the GOP structure in order of the display in coding order and outputs the rearranged images to the calculation unit  33 , the intra prediction unit  46 , and the motion prediction/compensation unit  47 . 
     The calculation unit  33  serves as an encoding unit and performs coding by calculating a difference between a predicted image supplied from the predicted image selection unit  48  and a current coding image output from the screen rearrangement buffer  32 . More specifically, the calculation unit  33  performs coding by subtracting a predicted image supplied from the predicted image selection unit  48  from a current coding image output from the screen rearrangement buffer  32 . The calculation unit  33  outputs an image acquired as a result thereof to the orthogonal transform unit  34  as residual information. In addition, in a case where a predicted image is not supplied from the predicted image selection unit  48 , the calculation unit  33  directly outputs the image read from the screen rearrangement buffer  32  to the orthogonal transform unit  34  as the residual information. 
     The orthogonal transform unit  34  performs an orthogonal transform of the residual information output from the calculation unit  33 , thereby generating an orthogonal transform coefficient. The orthogonal transform unit  34  supplies the generated orthogonal transform coefficient to the quantization unit  35 . 
     The quantization unit  35  performs quantization of the orthogonal transform coefficient that is supplied from the orthogonal transform unit  34  by using quantization parameters supplied from the rate control unit  50 . The quantization unit  35  inputs the coefficient acquired as a result thereof to the lossless encoding unit  36 . 
     The lossless encoding unit  36  acquires information (hereinafter, referred to as intra prediction mode information) that represents an optimal intra prediction mode from the intra prediction unit  46 . In addition, the lossless encoding unit  36  acquires information (hereinafter, referred to as inter prediction mode information) that represents the optimal inter prediction mode, a motion vector, and the like from the motion prediction/compensation unit  47 . In addition, the lossless encoding unit  36  acquires the index of an RPS, the RPS, or the like from the reference image setting unit  49  and acquires quantization parameters from the rate control unit  50 . 
     In addition, the lossless encoding unit  36  acquires a storage flag, an index or an offset, and type information from the adaptive offset filter  42  as offset filter information and acquires a filter coefficient from the adaptive loop filter  43 . 
     The lossless encoding unit  36  performs lossless coding such as variable length coding (for example, CAVLC (Context-Adaptive Variable Length Coding) or the like) or arithmetic coding (for example, CABAC (Context-Adaptive Binary Arithmetic Coding) for the quantized coefficient that is supplied from the quantization unit  35 . 
     In addition, the lossless encoding unit  36  performs lossless coding of the quantization parameters, the offset filter information, and the filter coefficient such as the intra prediction mode information or the inter prediction mode information, the motion vector, the index of the RPS or the RPS as coding information relating to coding. The lossless encoding unit  36  supplies the coding information and the coefficients, which have been coded in a lossless manner to the accumulation buffer  37  as coded data so as to be stored therein. In addition, the coding information that has been coded in a lossless manner may be regarded as header information (slice header) of the coefficient that is coded in a lossless manner. 
     The accumulation buffer  37  temporarily stores the coded data supplied from the lossless encoding unit  36 . In addition, the accumulation buffer  37  supplies the coded data that is stored to the setting unit  12  illustrated in  FIG. 3 . 
     In addition, the quantized coefficient that is output from the quantization unit  35  is input also to the inverse quantization unit  38 . The inverse quantization unit  38  performs inverse quantization of the coefficient quantized by the quantization unit  35  by using the quantization parameters supplied from the rate control unit  50  and supplies an orthogonal transform coefficient acquired as a result thereof to the inverse orthogonal transform unit  39 . 
     The inverse orthogonal transform unit  39  performs an inverse orthogonal transform of the orthogonal transform coefficient supplied from the inverse quantization unit  38 . The inverse orthogonal transform unit  39  supplies residual information acquired as a result of the inverse orthogonal transform to the addition unit  40 . 
     The addition unit  40  adds the residual information supplied from the inverse orthogonal transform unit  39  and the predicted image supplied from the predicted image selection unit  48 , thereby acquiring an image that has been locally decoded. In addition, in a case where the predicted image is not supplied from the predicted image selection unit  48 , the addition unit  40  sets the residual information supplied from the inverse orthogonal transform unit  39  as a locally decoded image. The addition unit  40  supplies the locally decoded image to the deblocking filter  41  and supplies the locally decoded image to the frame memory  44  so as to be stored therein. 
     The deblocking filter  41  performs an adaptive deblocking filter process for removing a block distortion for the locally decoded image that is supplied from the addition unit  40  and supplies an image acquired as a result thereof to the adaptive offset filter  42 . 
     The adaptive offset filter  42  performs an adaptive offset filter (SAO: Sample adaptive offset) process that mainly removes ringing for the image after the adaptive deblocking filter process performed by the deblocking filter  41 . 
     More specifically, the adaptive offset filter  42  determines the type of adaptive offset filter process for each LCU (Largest Coding Unit) that is a maximal coding unit and acquires an offset that is used in the adaptive offset filter process. The adaptive offset filter  42  performs an adaptive offset filter process of the determined type for the image after the adaptive deblocking filter process by using the acquired offset. Then, the adaptive offset filter  42  supplies the image after the adaptive offset filter process to the adaptive loop filter  43 . 
     In addition, the adaptive offset filter  42  has a buffer in which an offset is stored. The adaptive offset filter  42 , for each LCU, determines whether or not the offset used for the adaptive deblocking filter process has already been stored in the buffer. 
     In a case where it is determined that the offset used for the adaptive deblocking filter process has already been stored in the buffer, the adaptive offset filter  42  sets the storage flag, which represents whether or not the offset is stored in the buffer, to a value (here, “1”) representing that the offset is stored in the buffer. 
     Then, the adaptive offset filter  42 , for each LCU, supplies the storage flag set to “1”, the index that represents the storage position of an offset in the buffer, and the type information that represents the type of the adaptive offset filter process that has been performed to the lossless encoding unit  36 . 
     On the other hand, in a case where the offset used in the adaptive deblocking filter process has not been stored in the buffer, the adaptive offset filter  42  stores the offset in order in the buffer. In addition, the adaptive offset filter  42  sets the storage flag to a value (here, “0”) represents that the offset is not stored in the buffer. Then, the adaptive offset filter  42 , for each LCU, supplies the storage flag set to “0”, the offset, and the type information to the lossless encoding unit  36 . 
     The adaptive loop filter  43  performs, for example, for each LCU, an adaptive loop filter (ALF: Adaptive Loop Filter) process for the image after the adaptive offset filter process that is supplied from the adaptive offset filter  42 . As the adaptive loop filter process, for example, a process using a two-dimensional Wiener filter is used. It is apparent that a filter other than the Wiener filter may be used. 
     More specifically, the adaptive loop filter  93 , for each LCU, calculates a filter coefficient used in the adaptive loop filter process such that a residual between the original image that is an image output from the screen rearrangement buffer  32  and an image after the adaptive loop filter process is minimized. Then, the adaptive loop filter  43  performs, for each LCU, the adaptive loop filter process for the image after the adaptive offset filter process by using the calculated filter coefficient. 
     The adaptive loop filter  43  supplies the image after the adaptive loop filter process to the frame memory  44 . In addition, the adaptive loop filter  43  supplies the filter coefficient to the lossless encoding unit  36 . 
     Here, although the adaptive loop filter process is assumed to be performed for each LCU, the processing unit of the adaptive loop filter process is not limited to the LCU. However, by matching the processing units of the adaptive offset filter  42  and the adaptive loop filter  43  each other, the process can be efficiently performed. 
     The frame memory  44  stores the image supplied from the adaptive loop filter  43  and the image supplied from the addition unit  40 . The image stored in the frame memory  44  is output to the intra prediction unit  46  or the motion prediction/compensation unit  47  through the switch  45  as a reference image. 
     The intra prediction unit  46  performs intra prediction processes of all the intra prediction modes that are candidates by using the reference image read from the frame memory  44  through the switch  45 . 
     In addition, the intra prediction unit  46  calculates cost function values (to be described in detail) for all the intra prediction modes that are candidates based on the image read from the screen rearrangement buffer  32  and the predicted image generated as a result of the intra prediction process. Then, the intra prediction unit  46  determines an intra prediction mode of which the cost function value is the minimal as an optimal intra prediction mode. 
     The intra prediction unit  46  supplies the predicted image that is generated in the optimal intra prediction mode and a corresponding cost function value to the predicted image selection unit  48 . In a case where the intra prediction unit  46  is notified of the selection of the prediction image generated in the optimal intra prediction mode from the predicted image selection unit  48 , the intra prediction unit  46  supplies the intra prediction mode information to the lossless encoding unit  36 . 
     The cost function value is also called as an RD (Rate Distortion) cost and, for example, as defined in JM (Joint Model) that is reference software according to the H.264/AVC system, is calculated based on a technique of one of a high complexity mode and a low complexity mode. 
     More specifically, in a case where the high complexity mode is employed as the technique for calculating the cost function value, for all the prediction modes that are the candidates, decoding is temporarily performed for all the prediction modes that are the candidates, and a cost function value represented in the following Equation (1) is calculated for each prediction mode.
 
Cost(Mode)= D+λR   (1)
 
     Here, D is a difference (distortion) between the original image and the decoded image, R is the amount of generated coding including also the coefficient of the orthogonal transform, and λ is a Lagrange multiplier given as a function of the quantization parameter QP. 
     On the other hand, in a case where the low complexity mode is employed as the technique for calculating the cost function value, for each of all the prediction modes that are the candidates, the generation of a predicted image and the calculation of the coding amount of the coding information are performed, and a cost function represented in the following Equation (2) is calculated for each prediction mode.
 
Cost(Mode)= D +QPtoQuant(QP)Header_Bit  (2)
 
     Here, D is a difference (distortion) between the original image and the decoded image, Header_Bit is the coding amount of coding information, and QPtoQuant is a function given as a function of the quantization parameter QP. 
     In the low complexity mode, for all the prediction modes, only prediction images may be generated, and it is not necessary to generated decoded images, whereby the calculation amount is small. 
     The motion prediction/compensation unit  47  performs the motion prediction/compensation process of all the inter prediction modes that are the candidates. More specifically, the motion prediction/compensation unit  47  detects motion vectors of all the inter prediction modes that are the candidates based on the image supplied from the screen rearrangement buffer  32  and the reference image that is read from the frame memory  44  through the switch  45 . Then, the motion prediction/compensation unit  47  serves as a predicted image generation unit and generates predicted images by performing compensation processes of the reference image based on the motion vectors. 
     At this time, the motion prediction/compensation unit  47  calculates cost function values for all the inter prediction modes that are the candidates based on the image supplied from the screen rearrangement buffer  32  and the predicted images and determines an inter prediction mode of which the cost function value is the minimal as the optimal inter prediction mode. Then, the motion prediction/compensation unit  47  supplies the cost function value of the optimal inter prediction mode and a corresponding predicted image to the predicted image selection unit  48 . In addition, in a case where the motion prediction/compensation unit  47  is notified of the selection of the predicted image generated in the optimal inter prediction mode from the predicted image selection unit  48 , the motion prediction/compensation unit  47  outputs the inter prediction mode information, the corresponding motion vector, and the like to the lossless encoding unit  36  and outputs the reference image specifying information to the reference image setting unit  49 . 
     The predicted image selection unit  48  determines one of the optimal intra prediction and the optimal inter prediction mode of which the corresponding cost function value is less as the optimal prediction mode based on the cost function values supplied from the intra prediction unit  46  and the motion prediction/compensation unit  47 . Then, the predicted image selection unit  48  supplies the predicted image of the optimal prediction mode to the calculation unit  33  and the addition unit  40 . In addition, the predicted image selection unit  48  notifies the intra prediction unit  46  or the motion prediction/compensation unit  47  of the selection of the predicted image of the optimal prediction mode. 
     The reference image setting unit  49  maintains the reference image specifying information, which is supplied from the motion prediction/compensation unit  47 , corresponding to the GOP. In a case where the current coding image is a first image of the GOP, the reference image setting unit  49  supplies “0” as the index of the RPS and the RPS flag representing that the RPS of the current coding image is an RPS included in the SPS to the lossless encoding unit  36 . 
     On the other hand, in a case where the current coding image is an image other than the first image of the GOP, the reference image setting unit  49  compares the maintained reference image specifying information of the prior image and the reference image specifying information of the current coding image with each other and determines inter_ref_pic_set_prediction_flag and delta_idx_minus1 based on a result of the comparison. Then, the reference image setting unit  49  sets the RPS including the determined inter_ref_pic_set_prediction_flag and the reference image specifying information of the current coding image or delta_idx_minus1 as the RPS of the current coding image. 
     Then, in a case where the RPS that is the same as the RPS of the current coding image is supplied from the setting unit  12 , the reference image setting unit  49  supplies the index of the RPS and the RPS flag representing that the RPS of the current coding image is the RPS included in the SPS to the lossless encoding unit  36 . On the other hand, in a case where the RPS that is the same as the RPS of the current coding image is not supplied from the setting unit  12 , the reference image setting unit  49  supplies the RPS of the current coding image and the RPS flag representing that the RPS of the current coding image is not the RPS included in the SPS to the lossless encoding unit  36 . 
     The rate control unit  50  determines quantization parameters used by the quantization unit  35  based on the coded data stored in the accumulation buffer  37  such that an overflow or an underflow does not occur. The rate control unit  50  supplies the determined quantization parameters to the quantization unit  35 , the lossless encoding unit  36 , and the inverse quantization unit  38 . 
     (Example of Syntax of SPS) 
       FIG. 5  is a diagram that illustrates an example of the syntax of the SPS that is set by the setting unit  12  illustrated in  FIG. 3 . 
     As illustrated in the 18th line in  FIG. 5 , the RPS of each index (i) is included in the SPS. 
     (Example of Syntax of RPS) 
       FIG. 6  is a diagram that illustrates an example of the syntax of the RPS. 
     While not illustrated in the figure, descriptions of the sixth line and subsequent lines illustrated in  FIG. 6  are the same as those of the third line and subsequent lines illustrated in  FIG. 1 . 
     As illustrated in the second and third lines in  FIG. 6 , in the RPS of which the index (idx) is zero, inter_ref_pic_set_prediction_flag is not included but the reference image specifying information included in a case where inter_ref_pic_set_prediction_flag is “0” is included. 
     On the other hand, as illustrated in the fourth and fifth lines, in the RPS of which index (idx) is other than “0”, inter_ref_pic_set_prediction_flag is included. Then, in a case where inter_ref_pic_set_prediction_flag is “0”, the reference image specifying information is included. On the other hand, in a case where inter_ref_pic_set_prediction_flag is “1”, delta_idx_minus1 is included. 
     (Description of Advantages of Present Technology) 
       FIG. 7  is a diagram that illustrates the information amount of the RPS that is set by the setting unit  12  illustrated in  FIG. 3 , and  FIG. 8  is a diagram that illustrates the information amount of a conventional RPS. 
     In the examples illustrated in  FIGS. 7 and 8 , the reference image specifying information of the second and eighth pictures from the start within the GOP is the same as the reference image specifying information of a prior picture in coding order. 
     In this case, as illustrated in  FIG. 7 , the setting unit  12  sets the reference image specifying information of the first picture of the GOP as the RPS of which the index is “0”. In addition, the setting unit  12 , for example, as the RPS of which the index is “1”, sets “1” as inter_ref_pic_set_prediction_flag and sets “0” as delta_idx_minus1. Thus, the index of the RPS of the first picture of the GOP is set as “0”, and the indexes of the RPS&#39;s of the second and eighth pictures are set as “1”. 
     In contrast, as illustrated in  FIG. 8 , in the conventional case, for example, as the RPS of which index is “0”, “0” as inter_ref_pic_set_prediction_flag and the reference image specifying information of the first picture of the GOP are set. In addition, similar to the case of the setting unit  12 , the RPS of which the index is “1” is set. Thus, the index of the first picture of the GOP is set as “0”, and the indexes of the RPS&#39;s of the second and eighth pictures are set as “1”. 
     As above, the setting unit  12  does not set inter_ref_pic_set_prediction_flag as the RPS of which the index is “0” that is used as the RPS of the first picture. In other words, since the first picture of the GOP does not have any prior picture in coding order, inter_ref_pic_set_prediction_flag is necessarily to be “0”. Accordingly, the setting unit  12  does not set inter_ref_pic_set_prediction_flag as the RPS, of which the index is “0”, used as the RPS of the first picture but sets only the reference image specifying information due to inter_ref_pic_set_prediction_flag being “0”. As a result, the amount of information of the RPS can be decreased from that of a conventional case by an amount corresponding to inter_ref_pic_set_prediction_flag of the first picture. 
     (Example of Syntax of Slice Header) 
       FIG. 9  is a diagram that illustrates an example of the syntax of a slice header. 
     As illustrated in the fifth line in  FIG. 9 , in the slice header, an RPS flag (short_term_ref_pic_set_sps_flag) of a corresponding coefficient is included. In addition, as illustrated in the sixth and seventh lines in  FIG. 9 , in a case where the RPS flag is “0” representing that the RPS of the current coding image is not the RPS included in the SPS, in the slice header, the RPS of a corresponding coefficient is included as short_term_ref_pic_set (num_short_term_ref_pic_sets). 
     On the other hand, as illustrated in the eighth and ninth lines in  FIG. 9 , in a case where the RPS flag is “1” representing that the RPS of the current coding image is the RPS included in the SPS, in the slice header, the index of the RPS of a corresponding coefficient is included as short_term_ref_pic_set_idx (num_short_term_ref_pic_sets). 
     (Description of Process of Encoding Device) 
       FIG. 10  is a flowchart that illustrates a generation process performed by the encoding device  10  illustrated in  FIG. 3 . 
     In Step S 11  illustrated in  FIG. 10 , the setting unit  12  of the encoding device  10  performs an RPS setting process for setting the RPS. This RPS setting process will be described in detail later with reference to  FIG. 11  to be described later. In Step S 12 , the encoding unit  11  performs a coding process for coding an image, which is configured in units of frames, input from the outside as an input signal in accordance with the HEVC system. This coding process will be described later in detail with reference to  FIGS. 12 and 13  to be described later. 
     In Step S 13 , the setting unit  12  sets the SPS that includes the RPS to which the index is assigned. In Step S 14 , the setting unit  12  sets the PPS. In Step S 15 , the setting unit  12  generates a coded stream based on the SPS and the PPS, which have been set, and the coded data supplied from the encoding unit  11 . The setting unit  12  supplies the coded stream to the transmission unit  13 . 
     In Step S 16 , the transmission unit  13  transmits the coded stream supplied from the setting unit  12  to the decoding device to be described later and ends the process. 
       FIG. 11  is a flowchart that illustrates an RPS setting process represented in Step S 11  that is illustrated in  FIG. 10  in detail. 
     In Step S 21  illustrated in  FIG. 11 , the setting unit  12  sets the index i of the RPS to “0”. In Step S 22 , it is determined whether or not the index i of the RPS is “0”. In Step S 22 , in a case where the index i of the RPS is determined to be “0”, in Step S 23 , the setting unit  12  sets inter_ref_pic_set_prediction_flag to “0”, and the process proceeds to Step S 25 . 
     On the other hand, in a case where the index i of the RPS is determined not to be “0” in Step S 22 , the setting unit  12 , in Step S 24 , sets the RPS of the index i as inter_ref_pic_set_prediction_flag, and the process proceeds to Step S 25 . 
     In Step S 25 , the setting unit  12  determines whether or not inter_ref_pic_set_prediction_flag is “1”. In a case where it is determined that inter_ref_pic_set_prediction_flag is “1” in Step S 25 , in Step S 26 , the setting unit  12  sets delta_idx_minus1 as the RPS of the index i, and the process proceeds to Step S 28 . 
     On the other hand, in a case where it is determined that inter_ref_pic_set_prediction_flag is not “1” in Step S 25 , in other words, in a case where inter_ref_pic_set_prediction_flag is “0”, in Step S 27 , the setting unit  12  sets the reference image specifying information, and the process proceeds to Step S 28 . 
     In Step S 28 , the setting unit  12  increments the index i by one. In Step S 29 , the setting unit  12  determines whether or not the index i is equal to or larger than the number num_short_term_ref_pic_sets of RPS&#39;s included in the SPS. 
     In a case where it is determined that the index i is not the number num_short_term_ref_pic_sets or more in Step S 29 , the process is returned to Step S 22 , and the process of Steps S 22  to S 29  is repeated until the index i becomes the number num_short_term_ref_pic_sets or more. 
     On the other hand, in a case where it is determined that the index i is the number num_short_term_ref_pic_sets or more in Step S 29 , the process is returned to Step S 11  illustrated in  FIG. 10  and proceeds to Step S 12 . 
       FIGS. 12 and 13  represent a flowchart that illustrates the coding process of Step S 12  illustrated in  FIG. 10  in detail. 
     In Step S 31  illustrated in  FIG. 12 , the A/D converter  31  of the encoding unit  11  performs A/D conversion of an image, which is in units of frames, input as an input signal and outputs the converted image to the screen rearrangement buffer  32  so as to be stored therein. 
     In Step S 32 , the screen rearrangement buffer  32  rearranges the stored images of frames, which are arranged in display order, in order for coding in accordance with the structure of the GOP. The screen rearrangement buffer  32  supplies the images that are configured in units of frames after the rearrangement to the calculation unit  33 , the intra prediction unit  46 , and the motion prediction/compensation unit  47 . 
     In Step S 33 , the intra prediction unit  46  performs an intra prediction process of all the intra prediction modes that are candidates. In addition, the intra prediction unit  46  calculates cost function values for all the intra prediction modes that are the candidates based on based on the image read from the screen rearrangement buffer  32  and the predicted image generated as a result of the intra prediction process. Then, the intra prediction unit  46  determines an intra prediction mode of which the cost function value is the minimal as an optimal intra prediction mode. The intra prediction unit  46  supplies the predicted image generated in the optimal intra prediction mode and a corresponding cost function value to the predicted image selection unit  48 . 
     In addition, the motion prediction/compensation unit  47  performs a motion prediction/compensation process of all the inter prediction modes that are candidates. Furthermore, the motion prediction/compensation unit  47  calculates cost function values of all the inter prediction modes that are the candidates based on the image supplied from the screen rearrangement buffer  32  and the predicted images and determines an inter prediction mode of which the cost function value is the minimal as an optimal inter prediction mode. Then, the motion prediction/compensation unit  47  supplies the cost function value of the optimal inter prediction mode and a corresponding predicted image to the predicted image selection unit  48 . 
     In Step S 34 , the predicted image selection unit  48  determines one of the optimal intra prediction mode and the optimal inter prediction mode of which the cost function value is the minimal as an optimal prediction mode based on the cost function values supplied from the intra prediction unit  46  and the motion prediction/compensation unit  47  in the process of Step S 33 . Then, the predicted image selection unit  48  supplies a predicted image of the optimal prediction mode to the calculation unit  33  and the addition unit  40 . 
     In Step S 35 , the predicted image selection unit  48  determines whether or not the optimal prediction mode is the optimal inter prediction mode. In a case where it is determined that the optimal prediction mode is the optimal inter prediction mode in Step S 35 , the predicted image selection unit  48  notifies the motion prediction/compensation unit  47  of the selection of the predicted image generated in the optimal inter prediction mode. 
     Then, in Step S 36 , the motion prediction/compensation unit  47  supplies the inter prediction mode information and a corresponding motion vector to the lossless encoding unit  36 . The motion prediction/compensation unit  47  supplies the reference image specifying information to the reference image setting unit  49 . 
     In Step S 37 , the reference image setting unit  49  performs an RPS index determining process for determining the index of the RPS. This RPS index determining process will be described later in detail with reference to  FIG. 14  to be described later. 
     On the other hand, in Step S 35 , in a case where it is determined that the optimal prediction mode is not the optimal inter prediction mode, in other words, in a case where the optimal prediction mode is the optimal intra prediction mode, the predicted image selection unit  48  notifies the intra prediction unit  46  of the selection of the predicted image generated in the optimal intra prediction mode. Then, in Step S 38 , the intra prediction unit  46  supplies the intra prediction mode information to the lossless encoding unit  36 , and the process proceeds to Step S 39 . 
     In Step S 39 , the calculation unit  33  subtracts the predicted image supplied from the predicted image selection unit  48  from the image supplied from the screen rearrangement buffer  32 , thereby performing coding. The calculation unit  33  outputs an image acquired as a result thereof to the orthogonal transform unit  34  as residual information. 
     In Step S 40 , the orthogonal transform unit  34  performs an orthogonal transform for the residual information output from the calculation unit  33  and supplies an orthogonal transform coefficient acquired as a result thereof to the quantization unit  35 . 
     In Step S 41 , the quantization unit  35  quantizes the coefficient supplied from the orthogonal transform unit  34  by using the quantization parameters supplied from the rate control unit  50 . The quantized coefficient is input to the lossless encoding unit  36  and the inverse quantization unit  38 . 
     In Step S 42  illustrated in  FIG. 13 , the inverse quantization unit  38  performs inverse quantization of the quantized coefficient supplied from the quantization unit  35  by using the quantization parameters supplied from the rate control unit  50  and supplies an orthogonal transform coefficient acquired as a result thereof to the inverse orthogonal transform unit  39 . 
     In Step S 43 , the inverse orthogonal transform unit  39  performs an inverse orthogonal transform for the orthogonal transform coefficient supplied from the inverse quantization unit  38  and supplies residual information acquired as a result thereof to the addition unit  40 . 
     In Step S 44 , the addition unit  40  adds the residual information supplied from the inverse orthogonal transform unit  39  and the predicted image supplied from the predicted image selection unit  48 , thereby acquiring a locally decoded image. The addition unit  40  supplies the acquired image to the deblocking filter  41  and the frame memory  44 . 
     In Step S 45 , the deblocking filter  41  performs a deblocking filter process for the locally decoded image that is supplied from the addition unit  40 . The deblocking filter  41  supplies an image acquired as a result thereof to the adaptive offset filter  42 . 
     In Step S 46 , the adaptive offset filter  42  performs an adaptive offset filter process for the image supplied from the deblocking filter  41  for each LCU. The adaptive offset filter  42  supplies an image acquired as a result thereof to the adaptive loop filter  43 . In addition, the adaptive offset filter  42 , for each LCU, supplies the storage flag, the index or the offset, and the type information to the lossless encoding unit  36  as the offset filter information. 
     In Step S 47 , the adaptive loop filter  43  performs an adaptive loop filter process for the image supplied from the adaptive offset filter  42  for each LCU. The adaptive loop filter  43  supplies an image acquired as a result thereof to the frame memory  44 . In addition, the adaptive loop filter  43  supplies the filter coefficient used in the adaptive loop filter process to the lossless encoding unit  36 . 
     In Step S 48 , the frame memory  44  stores the image supplied from the adaptive loop filter  43  and the image supplied from the addition unit  40 . The images stored in the frame memory  44  are output to the intra prediction unit  46  or the motion prediction/compensation unit  47  through the switch  45  as reference images. 
     In Step S 49 , the lossless encoding unit  36  performs lossless coding for quantization parameters, offset filter information, and filter coefficients, which are supplied from the rate control unit  50 , such as the intra prediction mode information or the inter prediction mode information, the motion vector, the index of the RPS or the RPS, and the like as coding information. 
     In Step S 50 , the lossless encoding unit  36  performs lossless coding for the quantized coefficient supplied from the quantization unit  35 . Then, the lossless encoding unit  36  generates coded data based on the coding information and the coefficient that have been coded in a lossless manner in the process of Step S 49 . 
     In Step S 51 , the accumulation buffer  37  temporarily stores the coded data supplied from the lossless encoding unit  36 . 
     In Step S 52 , the rate control unit  50  determines the quantization parameters used by the quantization unit  35  based on the coded data stored in the accumulation buffer  37  such that an overflow or an underflow does not occur. The rate control unit  50  supplies the determined quantization parameters to the quantization unit  35 , the lossless encoding unit  36 , and the inverse quantization unit  38 . 
     In Step S 53 , the accumulation buffer  37  outputs the stored coded data to the setting unit  12  illustrated in  FIG. 3 . 
     In the coding process illustrated in  FIGS. 12 and 13 , for the simplification of description, while both the intra prediction process and the motion prediction/compensation process are configured to be constantly performed, actually, only one thereof may be performed in accordance with the picture type or the like. 
       FIG. 14  is a flowchart that illustrates the RPS index determining process represented in Step S 37  illustrated in  FIG. 12  in detail. 
     In Step S 71  illustrated in  FIG. 14 , the reference image setting unit  49  maintains the reference image specifying information, which is supplied from the motion prediction/compensation unit  47 , corresponding to the GOP. In Step S 72 , the reference image setting unit  49  determines whether or not the current coding image is the first image of the GOP. 
     In a case where the current coding image is determined to be the first image of the GOP in Step S 72 , in Step S 73 , the reference image setting unit  49  sets the RPS flag to “1”. In Step S 74 , the reference image setting unit  49  sets the index of the RPS to “0”, and the process proceeds to Step S 79 . 
     On the other hand, in a case where the current coding image is determined to be an image other than the first image of the GOP in Step S 72 , in Step S 75 , the reference image setting unit  49  generates an RPS of the current coding image. 
     More specifically, the reference image setting unit  49  determines whether or not the maintained reference image specifying information of the prior image and the reference image specifying information of the current coding image are the same. In a case where the maintained reference image specifying information of the prior image and the reference image specifying information of the current coding image are determined to be the same, the reference image setting unit  49  generates the RPS of the current coding image that includes “1” as inter_ref_pic_set_prediction_flag and includes delta_idx_minus1. 
     On the other hand, in a case where the maintained reference image specifying information of the prior image and the reference image specifying information of the current coding image are determined not to be the same, the reference image setting unit  49  generates the RPS of the current coding image that includes “0” as inter_ref_pic_set_prediction_flag. 
     In Step S 76 , the reference image setting unit  49  determines whether or not the RPS of the current coding image is the same as the RPS included in the SPS that is supplied from the setting unit  12 . In Step S 76 , in a case where the RPS of the current coding image is determined to be the same as the RPS included in the SPS, in Step S 77 , the reference image setting unit  49  sets the RPS flag to “1”. 
     In Step S 78 , the reference image setting unit  49  recognizes the index of the RPS included in the SPS that is the same as the RPS of the current coding image, and the process proceeds to Step S 79 . In Step S 79 , the reference image setting unit  49  supplies the RPS flag set in Step S 73  or Step S 77  and the index of the RPS that is set in Step S 74  or the index of the RPS that is recognized in Step S 78  to the lossless encoding unit  36 . Then, the process is returned to Step S 37  illustrated in  FIG. 12 , and the process proceeds to Step S 39 . 
     On the other hand, in a case where the RPS of the current coding image is determined not to be the same as the RPS included in the SPS in Step S 76 , the reference image setting unit  49  sets the RPS flag to “0”. In Step S 81 , the reference image setting unit  49  supplies the RPS flag set in Step S 80  and the RPS generated in Step S 75  to the lossless encoding unit  36 . Then, the process is returned to Step S 37  illustrated in  FIG. 12 , and the process proceeds to Step S 39 . 
     As above, in a case where the current coding image is an image other than the first image of the GOP, the encoding device  10  transmits inter_ref_pic_set_prediction_flag. In other words, in a case where the current coding image is the first image of the GOP, the encoding device  10  does not transmit inter_ref_pic_set_prediction_flag. Accordingly, the information amount of the RPS relating to the reference image specifying information can be decreased by an amount corresponding to inter_ref_pic_set_prediction_flag of the first image of the GOP. 
     (Configuration Example of Decoding Device According to First Embodiment) 
       FIG. 15  is a block diagram that illustrates an example of the configuration of a decoding device, to which the present technology is applied, according to the first embodiment that decodes a coded stream transmitted from the encoding device  10  illustrated in  FIG. 3 . 
     The decoding device  110  illustrated in  FIG. 15  is configured by a reception unit  111 , an extraction unit  112 , and a decoding unit  113 . 
     The reception unit  111  of the decoding device  110  receives a coded stream that is transmitted from the encoding device  10  illustrated in  FIG. 3  and supplies the received coded stream to the extraction unit  112 . 
     The extraction unit  112  extracts an SPS, a PPS, coded data, and the like from the coded stream that is supplied from the reception unit  111 . The extraction unit  112  supplies the coded data to the decoding unit  113 . In addition, the extraction unit  112 , based on the SPS, acquires inter_ref_pic_set_prediction_flag of each RPS and delta_idx_minus1 or the reference image specifying information and supplies the acquired information to the decoding unit  113 . In addition, the extraction unit  112  supplies information other than the RPS included in the SPS, the PPS, and the like to the decoding unit  113  as is necessary. 
     Based on inter_ref_pic_set_prediction_flag of each RPS and delta_idx_minus1 or the reference image specifying information supplied from the extraction unit  112 , the decoding unit  113  decodes the coded data supplied from the extraction unit  112  in accordance with the HEVC system. At this time, the decoding unit  113  refers to information other than the RPS included in the SPS, the PPS, and the like as is necessary. The decoding unit  113  outputs an image acquired as a result of the decoding as an output signal. 
     (Configuration Example of Decoding Unit) 
       FIG. 16  is a block diagram that illustrates an example of the configuration of the decoding unit  113  illustrated in  FIG. 15 . 
     The decoding unit  113  illustrated in  FIG. 16  is configured by: an accumulation buffer  131 ; a lossless decoding unit  132 ; an inverse quantization unit  133 ; an inverse orthogonal transform unit  134 ; an addition unit  135 ; a deblocking filter  136 ; an adaptive offset filter  137 ; an adaptive loop filter  138 ; a screen rearrangement buffer  139 ; a D/A converter  140 ; a frame memory  141 ; a switch  142 ; an intra prediction unit  143 ; a reference image setting unit  144 ; a motion compensation unit  145 ; and a switch  146 . 
     The accumulation buffer  131  of the decoding unit  113  receives coded data from the extraction unit  112  illustrated in  FIG. 15  and stores the received coded data. The accumulation buffer  131  supplies the stored decoded data to the lossless decoding unit  132 . 
     The lossless decoding unit  132  performs lossless decoding such as variable-length decoding or arithmetic decoding for the coded data supplied from the accumulation buffer  131 , thereby acquiring quantized coefficients and coding information. The lossless decoding unit  132  supplies the quantized coefficients to the inverse quantization unit  133 . In addition, the lossless decoding unit  132  supplies the intra prediction mode information and the like as the coding information to the intra prediction unit  143  and supplies the motion vector, the inter prediction mode information, and the like to the motion compensation unit  145 . The lossless decoding unit  132  supplies the RPS flag and the index of the RPS or the RPS to the reference image setting unit  144  as the coding information. 
     In addition, the lossless decoding unit  132  supplies the intra prediction mode information or the inter prediction mode information as the coding information to the switch  146 . The lossless decoding unit  132  supplies the offset filter information as the coding information to the adaptive offset filter  137  and supplies the filter coefficient to the adaptive loop filter  138 . 
     The inverse quantization unit  133 , the inverse orthogonal transform unit  134 , the addition unit  135 , the deblocking filter  136 , the adaptive offset filter  137 , the adaptive loop filter  138 , the frame memory  141 , the switch  142 , the intra prediction unit  143 , and the motion compensation unit  145  perform processes that are similar to those of the inverse quantization unit  38 , the inverse orthogonal transform unit  39 , the addition unit  40 , the deblocking filter  41 , the adaptive offset filter  42 , the adaptive loop filter  43 , the frame memory  44 , the switch  45 , the intra prediction unit  46 , and the motion prediction/compensation unit  47  illustrated in  FIG. 4 , whereby the image is decoded. 
     More specifically, the inverse quantization unit  133  performs inverse quantization of the quantized coefficients supplied from the lossless decoding unit  132  and supplies orthogonal transform coefficients acquired as a result thereof to the inverse orthogonal transform unit  134 . 
     The inverse orthogonal transform unit  134  performs an inverse orthogonal transform for the orthogonal transform coefficients supplied from the inverse quantization unit  133 . The inverse orthogonal transform unit  134  supplies residual information acquired as a result of the inverse orthogonal transform to the addition unit  135 . 
     The addition unit  135  serves as a decoding unit and performs decoding by adding the residual information that is supplied from the inverse orthogonal transform unit  134  as a current decoding image and the predicted image supplied from the switch  146 . The addition unit  135  supplies an image acquired as a result of the decoding to the deblocking filter  136  and the frame memory  141 . In addition, in a case where the predicted image is not supplied from the switch  146 , the addition unit  135  supplies the image that is the residual information supplied from the inverse orthogonal transform unit  134  to the deblocking filter  136  as an image acquired as a result of the decoding and supplies the image to the frame memory  141  so as to be stored therein. 
     The deblocking filter  136  performs an adaptive deblocking filter process for the image supplied from the addition unit  135  and supplies an image acquired as a result thereof to the adaptive offset filter  137 . 
     The adaptive offset filter  137  has a buffer that sequentially stores offsets supplied from the lossless decoding unit  132 . In addition, the adaptive offset filter  137 , for each LCU, performs an adaptive offset filter process for the image after the adaptive deblocking filter process performed by the deblocking filter  136  based on the offset filter information supplied from the lossless decoding unit  132 . 
     More specifically, in a case where the storage flag included in the offset filter information is “0”, the adaptive offset filter  137  performs an adaptive offset filter process of a type represented by the type information by using the offset included in the offset filter information for the image after the deblocking filter process that is performed in units of LCUs. 
     On the other hand, in a case where the storage flag included in the offset filter information is “1”, the adaptive offset filter  137  reads an offset that is stored at a position represented by the index included in the offset filter information for the image after the deblocking filter process performed in units of LCUs. Then, the adaptive offset filter  137  performs an adaptive offset filter process of a type represented by the type information by using the read offset. The adaptive offset filter  137  supplies the image after the adaptive offset filter process to the adaptive loop filter  138 . 
     The adaptive loop filter  138  performs the adaptive loop filter process for each LCU for the image supplied from the adaptive offset filter  137  by using the filter coefficients supplied from the lossless decoding unit  132 . The adaptive loop filter  138  supplies an image acquired as a result thereof to the frame memory  141  and the screen rearrangement buffer  139 . 
     The screen rearrangement buffer  139  stores images supplied from the adaptive loop filter  138  in units of frames. The screen rearrangement buffer  139  rearranges the stored images, which are in units of frames that are arranged in order for coding in the original order and supplies the rearranged images to the D/A converter  140 . 
     The D/A converter  140  performs D/A conversion of the image, which is configured in units of frames, supplied from the screen rearrangement buffer  139  and outputs the converted image as an output signal. The frame memory  141  stores the image supplied from the adaptive loop filter  138  and the image supplied from the addition unit  135 . The image stored in the frame memory  141  is read as a reference image and is supplied to the motion compensation unit  145  or the intra prediction unit  143  through the switch  142 . 
     The intra prediction unit  143  performs an intra prediction process of an intra prediction mode represented by the intra prediction mode information supplied from the lossless decoding unit  132  by using the reference image read from the frame memory  141  through the switch  142 . The intra prediction unit  143  supplies a predicted image generated as a result thereof to the switch  146 . 
     The reference image setting unit  144  maintains inter_ref_pic_set_prediction_flag of each RPS and delta_idx_minus1 or the reference image specifying information supplied from the extraction unit  112  illustrated in  FIG. 15  as the RPS information. In addition, the reference image setting unit  144  generates the reference image specifying information of the current decoding image based on the RPS flag and the index of the RPS or the RPS and the RPS information of each RPS that are supplied from the lossless decoding unit  132 . The reference image setting unit  144  supplies the generated reference image specifying information to the motion compensation unit  145  and maintains the reference image specifying information. 
     The motion compensation unit  145  reads a reference image specified by the reference image specifying information from the frame memory  141  through the switch  142  based on the reference image specifying information that is supplied from the reference image setting unit  144 . The motion compensation unit  145  serves as a predicted image generation unit and performs a motion compensation process of an optimal inter prediction mode that is represented by the inter prediction mode information by using the motion vector and the reference image. The motion compensation unit  145  supplies a predicted image generated as a result thereof to the switch  146 . 
     In a case where the intra prediction mode information is supplied from the lossless decoding unit  132 , the switch  146  supplies the predicted image supplied from the intra prediction unit  143  to the addition unit  135 . On the other hand, in a case where the inter prediction mode information is supplied from the lossless decoding unit  132 , the switch  146  supplies the predicted image supplied from the motion compensation unit  145  to the addition unit  135 . 
     (Description of Process of Decoding Device) 
       FIG. 17  is a flowchart that illustrates a reception process performed by the decoding device  110  illustrated in  FIG. 15 . 
     In Step S 111  illustrated in  FIG. 17 , the reception unit  111  of the decoding device  110  receives a coded stream transmitted from the encoding device  10  illustrated in  FIG. 3  and supplies the received coded stream to the extraction unit  112 . 
     In Step S 112 , the extraction unit  112  extracts the SPS, the PPS, the coded data, and the like from the coded stream that is supplied from the reception unit  111 . The extraction unit  112  supplies the coded data to the decoding unit  113 . In addition, the extraction unit  112  supplies information other than the RPS that is included in the SPS, the PPS, and the like to the decoding unit  113  as is necessary. 
     In Step S 113 , the extraction unit  112  acquires inter_ref_pic_set_prediction_flag of each RPS and delta_idx_minus1 or the reference image specifying information as the RPS information based on the SPS and supplies the acquired information to the decoding unit  113 . 
     In Step S 114 , the decoding unit  113  performs a decoding process for decoding the coded data supplied from the extraction unit  112  in accordance with the HEVC system based on the RPS information of each RPS that is supplied from the extraction unit  112 . This decoding process will be described in detail with reference to  FIG. 19  to be described later. Then, the process ends. 
       FIG. 18  is a flowchart that illustrates the RPS setting process represented in Step S 113  illustrated in  FIG. 17  in detail. 
     In Step S 120  illustrated in  FIG. 18 , the extraction unit  112  acquires num_short_term_ref_pic_sets that is included in the SPS ( FIG. 5 ). In Step S 121 , the extraction unit  112  sets the index i of the RPS that corresponds to the generated RPS information to “0”. In Step S 122 , it is determined whether or not the index i of the RPS is “0”. 
     In a case where the index i is determined to be “0” in Step S 122 , in Step S 123 , the extraction unit  112  sets inter_ref_pic_set_prediction_flag included in the RPS information of the RPS of the index i to “0”, and the process proceeds to Step S 125 . 
     On the other hand, in a case where the index i is determined not to be “0” in Step S 122 , in Step S 124 , the extraction unit  112  acquires inter_ref_pic_set_prediction_flag included in the RPS of the index i that is included in the SPS. Then, the extraction unit  112  sets the acquired inter_ref_pic_set_prediction_flag as inter_ref_pic_set_prediction_flag included in the RPS information of the RPS of the index i, and the process proceeds to Step S 125 . 
     In Step S 125 , the extraction unit  112  determines whether or not inter_ref_pic_set_prediction_flag is “1”. In a case where inter_ref_pic_set_prediction_flag is determined to be “1” in Step S 125 , in Step S 126 , the extraction unit  112  acquires delta_idx_minus1 included in the RPS of the index i that is included in the SPS. Then, the extraction unit  112  sets the acquired delta_idx_minus1 as delta_idx_minus1 included in the RPS information of the RPS of the index i, and the process proceeds to Step S 128 . 
     On the other hand, in a case where inter_ref_pic_set_prediction_flag is determined not to be “1” in Step S 125 , in Step S 127 , the extraction unit  112  acquires the reference image specifying information included in the RPS of the index i that is included in the SPS. Then, the extraction unit  112  sets the acquired reference image specifying information as the reference image specifying information included in the RPS information of the RPS of the index i, and the process proceeds to Step S 128 . 
     In Step S 128 , the extraction unit  112  increments the index i by one. In Step S 129 , the extraction unit  112  determines whether or not the index i is num_short_term_ref_pic_sets acquired in Step S 120  or more. 
     In a case where the index i is determined not to be num_short_term_ref_pic_sets or more in Step S 129 , the process is returned to Step S 122 , and the process of Steps S 122  to S 129  is repeated until the index i is num_short_term_ref_pic_sets or more. 
     On the other hand, in a case where the index i is determined to be num_short_term_ref_pic_sets or more in Step S 129 , in Step S 130 , the extraction unit  112  supplies the RPS information of RPS&#39;s of which the number is the set num_short_term_ref_pic_sets. Then, the process is returned to Step S 113  illustrated in  FIG. 17 , and the process proceeds to Step S 114 . 
       FIG. 19  is a flowchart that illustrates the decoding process represented in Step S 114  illustrated in  FIG. 17  in detail. 
     In Step S 131  illustrated in  FIG. 19 , the accumulation buffer  131  of the decoding unit  113  receives coded data, which is configured in units of frames, from the extraction unit  112  illustrated in  FIG. 15  and stores the received coded data. The accumulation buffer  131  supplies the stored coded data to the lossless decoding unit  132 . 
     In Step S 132 , the lossless decoding unit  132  performs lossless decoding of the coded data supplied from the accumulation buffer  131 , thereby acquires the quantized coefficients and the coding information. The lossless decoding unit  132  supplies the quantized coefficients to the inverse quantization unit  133 . In addition, the lossless decoding unit  132  supplies the intra prediction mode information and the like as the coding information to the intra prediction unit  143  and supplies the motion vector, the inter prediction mode information, the RPS flag, the index of the RPS or the RPS, and the like to the motion compensation unit  145 . 
     In addition, the lossless decoding unit  132  supplies the intra prediction mode information or the inter prediction mode information as the coding information to the switch  146 . The lossless decoding unit  132  supplies the offset filter information as the coding information to the adaptive offset filter  137  and supplies the filter coefficients to the adaptive loop filter  138 . 
     In Step S 133 , the inverse quantization unit  133  performs inverse quantization of the quantized coefficients supplied from the lossless decoding unit  132  and supplies orthogonal transform coefficients acquired as a result thereof to the inverse orthogonal transform unit  134 . 
     In Step S 134 , the motion compensation unit  145  determines whether or not the inter prediction mode information is supplied from the lossless decoding unit  132 . In Step S 134 , in a case where the inter prediction mode information is determined to be supplied, the process proceeds to Step S 135 . 
     In Step S 135 , the reference image setting unit  144  generates the reference image specifying information of the current decoding image based on the RPS information of each RPS supplied from the extraction unit  112  and the RPS flag and the index of the RPS or the RPS supplied from the lossless decoding unit  132  and maintains the generated reference image specifying information. 
     More specifically, the reference image setting unit  144  maintains the RPS information of each RPS that is supplied from the extraction unit  112 . In a case where the RPS flag is “1”, the reference image setting unit  144  reads the RPS information of the index of the RPS that is included in the maintained RPS information. Then, in a case where inter_ref_pic_set_prediction_flag included in the read RPS information is “0”, the reference image setting unit  144  generates the reference image specifying information included in the RPS information as the reference image specifying information of the current decoding image and maintains the generated reference image specifying information. 
     On the other hand, in a case where inter_ref_pic_set_prediction_flag is “1”, the reference image setting unit  144  reads the reference image specifying information of the prior image that is specified by delta_idx_minus1 included in the RPS information from among the maintained reference image specifying information. Then, the reference image setting unit  144  generates and maintains the read reference image specifying information of the prior image as the reference image specifying information of the current decoding image. 
     In addition, in a case where the RPS flag is “0”, and inter_ref_pic_set_prediction_flag included in the RPS, which is supplied from the lossless decoding unit  132  together with the RPS flag, is “0”, the reference image setting unit  144  generates the reference image specifying information included in the RPS as the reference image specifying information of the current decoding image and maintains the generated reference image specifying information. On the other hand, in a case where inter_ref_pic_set_prediction_flag is “1”, the reference image setting unit  144  reads the reference image specifying information of the prior image specified by delta_idx_minus1 included in the RPS from among the maintained reference image specifying information. Then, the reference image setting unit  144  generates the read reference image specifying information of the prior image as the reference image specifying information of the current decoding image and maintains the generated reference image specifying information. 
     In Step S 136 , the motion compensation unit  145  reads a reference image based on the reference image specifying information supplied from the reference image setting unit  144  and performs a motion compensation process of an optimal inter prediction mode represented by the inter prediction mode information by using the motion vector and the reference image. The motion compensation unit  145  supplies a predicted image generated as a result thereof to the addition unit  135  through the switch  146 , and the process proceeds to Step S 138 . 
     On the other hand, in a case where the inter prediction mode information is determined not to be supplied in Step S 134 , in other words, in a case where the intra prediction mode information is supplied to the intra prediction unit  143 , the process proceeds to Step S 137 . 
     In Step S 137 , the intra prediction unit  143  performs an intra prediction process of an intra prediction mode represented by the intra prediction mode information by using the reference image read from the frame memory  141  through the switch  142 . The intra prediction unit  143  supplies the predicted image generated as a result of the intra prediction process to the addition unit  135  through the switch  146 , and the process proceeds to Step S 138 . 
     In Step S 138 , the inverse orthogonal transform unit  134  performs an inverse orthogonal transform for the orthogonal transform coefficients supplied from the inverse quantization unit  133  and supplies residual information acquired as a result thereof to the addition unit  135 . 
     In Step S 139 , the addition unit  135  adds the residual information supplied from the inverse orthogonal transform unit  134  and the predicted image supplied from the switch  146 . The addition unit  135  supplies an image acquired as a result thereof to the deblocking filter  136  and supplies the acquired image to the frame memory  141 . 
     In Step S 140 , the deblocking filter  136  performs a deblocking filter process for the image supplied from the addition unit  135 , thereby removing a block distortion. The deblocking filter  136  supplies the image acquired as a result thereof to the adaptive offset filter  137 . 
     In Step S 141 , the adaptive offset filter  137  performs an adaptive offset filter process for each LCU for the image after the deblocking filter process performed by the deblocking filter  136  based on the offset filter information supplied from the lossless decoding unit  132 . The adaptive offset filter  137  supplies the image after the adaptive offset filter process to the adaptive loop filter  138 . 
     In Step S 142 , the adaptive loop filter  138  performs an adaptive loop filter process for each LCU for the image supplied from the adaptive offset filter  137  by using the filter coefficients supplied from the lossless decoding unit  132 . The adaptive loop filter  138  supplies an image acquired as a result thereof to the frame memory  141  and the screen rearrangement buffer  139 . 
     In Step S 143 , the frame memory  141  stores the image supplied from the addition unit  135  and the image supplied from the adaptive loop filter  138 . The images stored in the frame memory  141  are supplied to the motion compensation unit  145  or the intra prediction unit  143  through the switch  142  as the reference images. 
     In Step S 144 , the screen rearrangement buffer  139  stores the images supplied from the adaptive loop filter  138  in units of frames and rearranges the stored images, which are configured in units of frames in coding order, in the original display order and supplies the rearranged images to the D/A converter  140 . 
     In Step S 145 , the D/A converter  140  performs D/A conversion for the image, which is configured in units of frames, supplied from the screen rearrangement buffer  139 , and outputs the converted image as an output signal. Then, the process is returned to Step S 114  illustrated in  FIG. 17 , and the process ends. 
     As above, the decoding device  110  receives inter_ref_pic_set_prediction_flag transmitted in a case where the current coding image is an image other than the first image of the GOP. In a case where inter_ref_pic_set_prediction_flag is received, the decoding device  110  generates the reference image specifying information of the current decoding image based on inter_ref_pic_set_prediction_flag. On the other hand, in a case where inter_ref_pic_set_prediction_flag is not received, the decoding device  110  generates the reference image specifying information of the current decoding image based on “0” as inter_ref_pic_set_prediction_flag. 
     As a result, the decoding device  110  can decode a coded stream in which the amount of information of the RPS is decreased by an amount corresponding to inter_ref_pic_set_prediction_flag of the first image of the GOP. 
     Second Embodiment 
     (Configuration Example of Encoding Device According to Second Embodiment) 
       FIG. 20  is a block diagram that illustrates an example of the configuration of an encoding device, to which the present technology is applied, according to the second embodiment. 
     Here, the same reference numeral is assigned to each configuration illustrated in  FIG. 20  that is the same as the configuration illustrated in  FIG. 3 , and the description thereof to be repeated will be omitted. 
     The configuration of the encoding device  150  illustrated in  FIG. 20  is different from the configuration of the encoding device  10  illustrated in  FIG. 3  in that a setting unit  151  is arranged instead of the setting unit  12 . The encoding device  150  sets an SPS such that inter_ref_pic_set_prediction_flag and delta_idx_minus1 can be shared in units of GOPs. 
     More specifically, the setting unit  151  sets RPS&#39;s including inter_ref_pic_set_prediction_flag, delta_idx_minus1, the reference image specifying information, and the like as is necessary and assigns an index to each RPS. The setting unit  151  supplies the RPS&#39;s to which the indexes have been assigned to the encoding unit  11 . In addition, the setting unit  151  includes reference unavailable information representing whether inter_ref_pic_set_prediction_flag is “0” in the RPS&#39;s and all the pictures within the GOP and sets SPS&#39;s delta_idx_minus1 that is common to all the pictures within the GOP as is necessary. The setting unit  151  sets the PPS and the like. 
     In addition, the setting unit  151 , similar to the setting unit  12  illustrated in  FIG. 3 , generates a coded stream based on the SPS&#39;s and the PPS, which have been set, and the coded data supplied from the encoding unit  11 . The setting unit  151 , similar to the setting unit  12 , supplies the coded stream to the transmission unit  13 . 
     (Example of Syntax of SPS) 
       FIG. 21  is a diagram that illustrates an example of the syntax of the SPS that is set by the setting unit  151  illustrated in  FIG. 20 . 
     As illustrated in the fourth line in  FIG. 21 , reference unavailable information (disable_rps_prediction_flag) is included in the SPS. In addition, as illustrated in the fifth and sixth lines, in a case where the reference unavailable information is “0” that does not represent that inter_ref_pic_set_prediction_flag is “0” in all the pictures within the GOP, identicalness information (unified_rps_prediction_control_present_flag) representing whether delta_idx_minus1 is identical in all the pictures within the GOP is included in the SPS. 
     Furthermore, as illustrated in the seventh and eighth lines, in a case where the identicalness information is “1” representing that delta_idx_minus1 is identical in all the pictures within the GOP, unified_delta_idx_minus1 that is delta_idx_minus1 common to all the pictures within the GOP is included in the SPS. In addition, as illustrated in the 11th line, the RPS of each index (i) is included in the SPS. 
     (Example of Syntax of RPS) 
       FIG. 22  is a diagram that illustrates an example of the syntax of the RPS. 
     The descriptions of the 11th line and subsequent lines illustrated in  FIG. 22  are the same as those of the fifth line and subsequent lines illustrated in  FIG. 1 . 
     As illustrated in the second and third lines in  FIG. 22 , in a case where disable_rps_prediction_flag is “1”, in the RPS, inter_ref_pic_set_prediction_flag is not included but the reference image specifying information included in a case where inter_ref_pic_set_prediction_flag is “0” is included. 
     On the other hand, as illustrated in the fourth and fifth lines, in a case where disable_rps_prediction_flag is “0”, in the RPS, inter_ref_pic_set_prediction_flag is included. In addition, as illustrated in the sixth to eighth lines, in a case where inter_ref_pic_set_prediction_flag and unified_rps_prediction_control_present_flag are respectively “1”, in the RPS, delta_idx_minus1 is not included, and delta_idx_minus1 is unified_delta_idx_minus1. 
     Furthermore, as illustrated in the ninth and tenth lines, in a case where inter_ref_pic_set_prediction_flag is “1” and unified_rps_prediction_control_present_flag is “0”, delta_idx_minus1 is included in the RPS. 
     (Description of Advantages of Present Technology) 
       FIGS. 23 and 24  are diagrams that illustrate the information amount of the RPS that is set by the setting unit  151  illustrated in  FIG. 20 , and  FIG. 25  is a diagram that illustrates the information amount of a conventional RPS. 
     In the example illustrated in  FIG. 23 , the reference image specifying information of each of the second picture and the eighth picture from the beginning within the GOP is identical to the reference image specifying information of a respective prior picture in coding order. 
     In this case, as illustrated in  FIG. 23 , the setting unit  151  sets “0” as disable_rps_prediction_flag and sets “1” as unified_rps_prediction_control_present_flag. In addition, the setting unit  151  sets “0” as unified_delta_idx_minus1. 
     Furthermore, the setting unit  151 , for example, as an RPS of which the index is “0”, sets “0” as inter_ref_pic_set_prediction_flag and sets the reference image specifying information of the first picture of the GOP. In addition, the setting unit  151 , as an RPS of which the index is “1”, sets “1” as inter_ref_pic_set_prediction_flag. Thus, the index of the RPS of the first picture of the GOP is set as “0”, and the indexes of the RPS&#39;s of the second and eighth pictures are set as “1”. 
     As above, the setting unit  151  sets delta_idx_minus1 that is common to all the pictures within the GOP as unified_delta_idx_minus1. Accordingly, the setting unit  151  can set delta_idx_minus1 in units of GOPs. 
     In addition, in the examples illustrated in  FIGS. 24 and 25 , the reference image specifying information of all the pictures within the GOP is not identical to the reference image specifying information of respective prior pictures in coding order. 
     In this case, as illustrated in  FIG. 24 , the setting unit  151  sets “1” as disable_rps_prediction_flag and, as an RPS corresponding to each picture within the GOP, sets the reference image specifying information of the picture. In contrast, in a conventional case, as illustrated in  FIG. 25 , as an RPS corresponding to each picture within the GOP, “0” is set as inter_ref_pic_set_prediction_flag, and the reference image specifying information of the picture is set. 
     As above, the setting unit  151  sets “0” as inter_ref_pic_set_prediction_flag common to all the pictures within the GOP as disable_rps_prediction_flag. Accordingly, in a case where disable_rps_prediction_flag is “1”, the amount of information of the RPS can be decreased by an amount corresponding to inter_ref_pic_set_prediction_flag from that of the conventional case. 
     (Description of Process of Encoding Device) 
     A generation process performed by the encoding device  150  illustrated in  FIG. 20  is the same as the generation process illustrated in  FIG. 10  except for the RPS setting process, and thus, hereinafter, only the RPS setting process will be described. 
       FIG. 26  is a flowchart that illustrates the RPS setting process performed by the setting unit  151  of the encoding device  150  in detail. 
     In Step S 161  illustrated in  FIG. 26 , the setting unit  151  sets disable_rps_prediction_flag as the SPS. In Step S 162 , the setting unit  151  determines whether or not disable_rps_prediction_flag is “1”. In a case where disable_rps_prediction_flag is determined not to be “1” in Step S 162 , in Step S 163 , the setting unit  151  sets unified_rps_prediction_control_present_flag as the SPS. 
     In Step S 164 , the setting unit  151  determines whether or not unified_rps_prediction_control_present_flag is “1”. In Step S 164 , in a case where unified_rps_prediction_control_present_flag is determined to be “1”, in Step S 165 , the setting unit  151  sets unified_delta_idx_minus1 is as SPS, and the process proceeds to Step S 166 . 
     In a case where disable_rps_prediction_flag is determined to be “1” in Step S 162  or in a case where unified_rps_prediction_control_present_flag is determined to be “0” in Step S 164 , the process proceeds to Step S 166 . 
     In Step S 166 , the setting unit  151  sets the index i of the RPS to “0”. In Step S 167 , the setting unit  151  determines whether or not disable_rps_prediction_flag is “1”. In a case where disable_rps_prediction_flag is determined to be “1” in Step S 167 , in Step S 168 , the setting unit  151  sets inter_ref_pic_set_prediction_flag to “0”, the process proceeds to Step S 170 . 
     On the other hand, in a case where disable_rps_prediction_flag is determined not to be “1” in Step S 167 , in Step S 169 , the setting unit  151  sets inter_ref_pic_set_prediction_flag as the RPS of the index i, the process proceeds to Step S 170 . 
     In Step S 170 , the setting unit  151  determines whether or not inter_ref_pic_set_prediction_flag is “1”. In a case where inter_ref_pic_set_prediction_flag is determined to be “1” in Step S 170 , in Step S 171 , the setting unit  151  determines whether or not unified_rps_prediction_control_present_flag is “1”. 
     In a case where unified_rps_prediction_control_present_flag is determined to be “1” in Step S 171 , the process proceeds to Step S 174 . On the other hand, in a case where unified_rps_prediction_control_present_lag is determined not to be “1” in Step S 171 , in Step S 172 , the setting unit  151  sets delta_idx_minus1 as the RPS of the index i, and the process proceeds to Step S 174 . 
     In addition, in a case where inter_ref_pic_set_prediction_flag is determined not to be “1” in Step S 170 , in Step S 173 , the setting unit  151  sets the reference image specifying information as the RPS of the index i, and the process proceeds to Step S 174 . 
     In Step S 174 , the setting unit  151  increments the index i by one. In Step S 175 , the setting unit  151  determines whether or not the index i is the number num_short_term_ref_pic_sets of RPS&#39;s included in the SPS or more. 
     In a case where the index i is determined not to be num_short_term_ref_pic_sets or more in Step S 175 , the process is returned to Step S 167 , and the process of Steps S 167  to S 175  is repeated until the index i is the number num_short_term_ref_pic_sets or more. 
     On the other hand, in a case where the index i is determined to be num_short_term_ref_pic_sets or more in Step S 175 , the RPS setting process ends. 
     As above, since the encoding device  150  sets disable_rps_prediction_flag, in a case where disable_rps_prediction_flag is “1”, the amount of information of the RPS relating to the reference image specifying information can be decreased by an amount corresponding to inter_ref_pic_set_prediction_flag from that of the conventional case. In addition, inter_ref_pic_set_prediction_flag can be set in units of GOPs. 
     Furthermore, since the encoding device  150  sets delta_idx_minus1 common to all the pictures within the GOP as unified_delta_idx_minus1, delta_idx_minus1 can be set in units of GOPs. 
     (Configuration Example of Decoding Device According to Second Embodiment) 
       FIG. 27  is a block diagram that illustrates an example of the configuration of a decoding device, to which the present technology is applied, according to the second embodiment that decodes a coded stream transmitted from the encoding device  150  illustrated in  FIG. 20 . 
     Here, the same reference numeral is assigned to each configuration illustrated in  FIG. 27  that is the same as the configuration illustrated in  FIG. 15 , and the description thereof to be repeated will be omitted. 
     The configuration of the decoding device  170  illustrated in  FIG. 27  is different from the configuration of the decoding device  110  illustrated in  FIG. 15  in that an extraction unit  171  is arranged instead of the extraction unit  112 . The decoding device  170  sets the RPS information of each RPS based on the SPS illustrated in  FIG. 21 . 
     More specifically, the extraction unit  171  of the decoding device  170 , similar to the extraction unit  112  illustrated in  FIG. 15 , extracts an SPS, a PPS, coded data, and the like from a coded stream that is supplied from the reception unit  111 . The extraction unit  171 , similar to the extraction unit  112 , supplies the coded data to the decoding unit  113 . In addition, the extraction unit  171 , based on the SPS illustrated in  FIG. 21 , acquires the RPS information of each RPS and supplies the acquired RPS information to the decoding unit  113 . Furthermore, the extraction unit  171 , similar to the extraction unit  112 , also supplies information other than the RPS included in the SPS, the PPS, and the like to the decoding unit  113  as is necessary. 
     (Description of Process of Decoding Device) 
     The reception process performed by the decoding device  170  illustrated in  FIG. 27  is the same as the reception process illustrated in  FIG. 17  except for the RPS setting process, and thus, hereinafter, only the RPS setting process will be described. 
       FIG. 28  is a flowchart that illustrates the RPS setting process performed by the decoding device  170  illustrated in  FIG. 27  in detail. 
     In Step S 191  illustrated in  FIG. 28 , the extraction unit  171  acquires num_short_term_ref_pic_sets included in the SPS ( FIG. 21 ). In Step S 192 , the extraction unit  171  acquires disable_rps_prediction_flag that is included in the SPS. In Step S 193 , the extraction unit  171  determines whether or not the acquired disable_rps_prediction_flag is “1”. 
     In a case where disable_rps_prediction_flag is determined not to be “1” in Step S 193 , in Step S 194 , the extraction unit  171  acquires unified_rps_prediction_control_present_flag that is included in the SPS. In Step S 195 , the extraction unit  171  determines whether or not the acquired unified_rps_prediction_control_present_flag is “1”. 
     In a case where unified_rps_prediction_control_present_flag is determined to be “1” in Step S 195 , the extraction unit  171  acquires unified_delta_idx_minus1 included in the SPS, and the process proceeds to Step S 197 . 
     On the other hand, in a case where unified_delta_idx_minus1 is determined not to be “1” in Step S 195 , the process proceeds to Step S 197 . In addition, in a case where disable_rps_prediction_flag is determined to be “1” in Step S 193 , the process proceeds to Step S 197 . 
     In Step S 197 , the extraction unit  171  sets the index i of the RPS corresponding to the generated RPS information to “0”. In Step S 198 , the extraction unit  171  determines whether or not the acquired disable_rps_prediction_flag acquired in Step S 192  is “1”. 
     In a case where disable_rps_prediction_flag is determined to be “1” in Step S 198 , in Step S 199 , the extraction unit  171  sets inter_ref_pic_set_prediction_flag included in the RPS information of the RPS of the index i to “0”, and the process proceeds to Step S 201 . 
     On the other hand, in a case where disable_rps_prediction_flag is determined not to be “1” in Step S 198 , in Step S 200 , the extraction unit  171  acquires inter_ref_pic_set_prediction_flag included in the RPS of the index i that is included in the SPS. Then, the extraction unit  171  sets the acquired inter_ref_pic_set_prediction_flag as inter_ref_pic_set_prediction_flag included in the RPS information of the RPS of the index i, and the process proceeds to Step S 201 . 
     In Step S 201 , the extraction unit  171  determines whether or not inter_ref_pic_set_prediction_flag is “1”. In a case where inter_ref_pic_set_prediction_flag is determined to be “1” in Step S 201 , in Step S 202 , the extraction unit  171  determines whether or not unified_rps_prediction_control_present_flag acquired in Step S 194  is “1”. 
     In a case where unified_rps_prediction_control_present_flag is determined to be “1” in Step S 202 , the process proceeds to Step S 203 . In Step S 203 , the extraction unit  171  sets unified_delta_idx_minus1 acquired in Step S 196  as unified_delta_idx_minus1 included in the RPS information of the RPS of the index i, and the process proceeds to Step S 206 . 
     On the other hand, in a case where unified_rps_prediction_control_present_flag is determined not to be “1” in Step S 202 , in Step S 204 , the extraction unit  171  acquires delta_idx_minus1 included in the RPS of the index i that is included in the SPS. Then, the extraction unit  171  sets the acquired delta_idx_minus1 as delta_idx_minus1 included in the RPS information of the RPS of the index i, and the process proceeds to Step S 206 . 
     On the other hand, in a case where inter_ref_pic_set_prediction_flag is determined not to be “1” in Step S 201 , in Step S 205 , the extraction unit  171  acquires the reference image specifying information included in the RPS of the index i that is included in the SPS. Then, the extraction unit  171  sets the acquired reference image specifying information as the reference image specifying information included in the RPS information of the RPS of the index i, and the process proceeds to Step S 206 . 
     The process of Steps S 206  to S 208  is similar to the process of Steps S 128  to S 130  illustrated in  FIG. 18 , and the description thereof will be omitted. 
     As above, the decoding device  170  receives disable_rps_prediction_flag and generates the reference image specifying information of the current decoding image based on disable_rps_prediction_flag. As a result, in a case where disable_rps_prediction_flag is “1”, the decoding device  170  can decode a coded stream in which the amount of information of the RPS is decreased by an amount corresponding to inter_ref_pic_set_prediction_flag. 
     In addition, the decoding device  170  receives delta_idx_minus1 that is common to all the pictures within the GOP as unified_delta_idx_minus1 and generates the reference image specifying information of the current decoding image based on unified_delta_idx_minus1. As a result, the decoding device  170  can decode the coded stream in which delta_idx_minus1 is set in units of GOPs. 
     Third Embodiment 
     (Configuration Example of Encoding Device According to Third Embodiment) 
       FIG. 29  is a block diagram that illustrates an example of the configuration of an encoding device, to which the present technology is applied, according to the third embodiment. 
     Here, the same reference numeral is assigned to each configuration illustrated in  FIG. 29  that is the same as the configuration illustrated in  FIG. 3 , and the description thereof to be repeated will be omitted. 
     The configuration of the encoding device  190  illustrated in  FIG. 29  is different from the configuration of the encoding device  10  illustrated in  FIG. 3  in that a setting unit  191  is arranged instead of the setting unit  12 . The encoding device  190  is acquired by combining the encoding device  10  illustrated in  FIG. 3  and the encoding device  150  illustrated in  FIG. 20 . 
     More specifically, the setting unit  191  of the encoding device  190  sets RPS&#39;s including an RPS that does not include inter_ref_pic_set_prediction_flag but includes the reference image specifying information and an RPS including inter_ref_pic_set_prediction_flag, delta_idx_minus1, the reference image specifying information, and the like as is necessary. In addition, the setting unit  191  assigns an index to each RPS. Here, as the index of the RPS that does not include inter_ref_pic_set_prediction_flag but includes the reference image specifying information, “0” is assigned. 
     The setting unit  191  supplies the RPS&#39;s to which indexes are assigned to the encoding unit  11 . In addition, the setting unit  191  sets the SPS that includes an RPS and disable_rps_prediction_flag and includes unified_rps_prediction_control_present_flag and unified_delta_idx_minus1 as is necessary. The setting unit  191  sets the PPS and the like. 
     In addition, the setting unit  191 , similar to the setting unit  12  illustrated in  FIG. 3 , generates a coded stream based on the SPS and the PPS, which have been set and coded data supplied from the encoding unit  11 . The setting unit  191 , similar to the setting unit  12 , supplies the coded steam to the transmission unit  13 . 
     (Example of Syntax of SPS) 
       FIG. 30  is a diagram that illustrates an example of the syntax of the SPS that is set by the setting unit  191  illustrated in  FIG. 29 . 
     The configuration illustrated in  FIG. 30  is the same as the configuration illustrated in  FIG. 21 , and thus the description thereof will be omitted. 
     (Example of Syntax of RPS) 
       FIG. 31  is a diagram that illustrates an example of the syntax of the RPS. 
     While not illustrated in the figure, descriptions of the 11th line and subsequent lines illustrated in  FIG. 31  are the same as those of the fifth line and subsequent lines illustrated in  FIG. 1 . 
     As illustrated in the second line and the third line illustrated in  FIG. 31 , in a case where the index (idx) is “0” or in a case where disable_rps_prediction_flag is “1”, in the RPS, inter_ref_pic_set_prediction_flag is not included but the reference image specifying information included in a case where inter_ref_pic_set_prediction_flag is “0” is included. 
     The descriptions of the fourth line to the tenth line are the same as those of the fourth line to the tenth line illustrated in  FIG. 22 , and thus, the descriptions will be omitted. 
     (Description of Advantages of Present Technology) 
       FIG. 32  is a diagram that illustrates the information amount of the RPS that is set by the setting unit  191  illustrated in  FIG. 29 . 
     In the example illustrated in  FIG. 32 , the reference image specifying information of the second and eighth pictures from the start within the GOP is the same as the reference image specifying information of a prior picture in coding order. 
     In this case, as illustrated in  FIG. 32 , the setting unit  191  sets “0” as disable_rps_prediction_flag and sets “1” as unified_rps_prediction_control_present_flag. In addition, the setting unit  191  sets “0” as unified_delta_idx_minus1. 
     Furthermore, the setting unit  191 , for example, sets the reference image specifying information of the first picture of the GOP as the RPS of which the index is “0”. In addition, the setting unit  191  sets “1” as inter_ref_pic_set_prediction_flag as the RPS of which the index is “1”. Thus, the index of the RPS of the first picture of the GOP is set as “0”, and the indexes of the RPS&#39;s of the second and eighth pictures are set as “1”. 
     As above, the setting unit  191  does not set inter_ref_pic_set_prediction_flag as the RPS of which the index is “0” that is used as the RPS of the first picture. Accordingly, the amount of information of the RPS can be decreased by an amount corresponding to inter_ref_pic_set_prediction_flag of the first picture from that of the conventional case illustrated in  FIG. 8 . 
     In addition, the setting unit  191  sets delta_idx_minus1 that is common to all the pictures within the GOP as unified_delta_idx_minus1. Accordingly, delta_idx_minus1 can be set in units of GOPs. 
     While not illustrated in the figure, the setting unit  191  sets “0” as inter_ref_pic_set_prediction_flag common to all the pictures within the GOP as disable_rps_prediction_flag. Accordingly, in a case where disable_rps_prediction_flag is “1”, the amount of information of the RPS can be also decreased by an amount corresponding to inter_ref_pic_set_prediction_flag of a picture other than the first picture from that of the conventional case. 
     (Description of Process of Encoding Device) 
     A generation process performed by the encoding device  190  illustrated in  FIG. 29  is the same as the generation process illustrated in  FIG. 10  except for the RPS setting process, and thus, hereinafter, only the RPS setting process will be described. 
       FIG. 33  is a flowchart that illustrates the RPS setting process performed by the setting unit  191  of the encoding device  190 . 
     The process of Steps S 221  to S 226  illustrated in  FIG. 33  is similar to the process of Steps S 161  to S 166  illustrated in  FIG. 26 , and thus, the description thereof will be omitted. 
     In Step S 227 , the setting unit  191  determines whether disable_rps_prediction_flag is “1” or the index i is “0”. In a case where it is determined that disable_rps_prediction_flag is “1” in Step S 227 , or the index i is “0”, the process proceeds to Step S 228 . On the other hand, in a case where it is determined that disable_rps_prediction_flag is not “1” in Step S 227 , and the index i is not “0”, the process proceeds to Step S 229 . 
     The process of Steps S 228  to S 235  is similar to the process of Steps S 168  to S 175  illustrated in  FIG. 26 , and thus, the description thereof will be omitted. 
     (Configuration Example of Decoding Device According to Third Embodiment) 
       FIG. 34  is a block diagram that illustrates an example of the configuration of the decoding device, to which the present technology is applied, according to the third embodiment that decodes a coded stream transmitted from the encoding device  190  illustrated in  FIG. 29 . 
     Here, the same reference numeral is assigned to each configuration illustrated in  FIG. 34  that is the same as the configuration illustrated in  FIG. 15 , and the description thereof to be repeated will be omitted. 
     The configuration of the decoding device  210  illustrated in  FIG. 34  is different from the configuration of the decoding device  110  illustrated in  FIG. 15  in that an extraction unit  211  is arranged instead of the extraction unit  112 . The decoding device  210  sets the RPS information of each RPS based on the SPS, which is illustrated in  FIG. 30 , including the RPS illustrated in  FIG. 31 . 
     More specifically, the extraction unit  211  of the decoding device  210 , similar to the extraction unit  112  illustrated in  FIG. 15 , extracts an SPS, a PPS, coded data, and the like from a coded stream that is supplied from the reception unit  111 . The extraction unit  211 , similar to the extraction unit  112 , supplies the coded data to the decoding unit  113 . In addition, the extraction unit  211 , based on the SPS, which is illustrated in  FIG. 30 , including the RPS illustrated in  FIG. 31  acquires the RPS information of each RPS and supplies the acquired RPS information to the decoding unit  113 . Furthermore, the extraction unit  211 , similar to the extraction unit  112 , also supplies information other than the RPS included in the SPS, the PPS, and the like to the decoding unit  113  as is necessary. 
     (Description of Process of Decoding Device) 
     The reception process performed by the decoding device  210  illustrated in  FIG. 34  is the same as the reception process illustrated in  FIG. 17  except for the RPS setting process, and thus, hereinafter, only the RPS setting process will be described. 
       FIG. 35  is a flowchart that illustrates the RPS setting process performed by the decoding device  210  illustrated in  FIG. 34  in detail. 
     The process of Steps S 251  to S 257  illustrated in  FIG. 35  is similar to the process of Steps S 191  to S 197  illustrated in  FIG. 28 , and thus, the description thereof will be omitted. 
     In Step S 258 , the extraction unit  211  determines whether disable_rps_prediction_flag acquired in Step S 252  is “1” or the index i is “0”. 
     In a case where it is determined that disable_rps_prediction_flag is “1” or the index i is “0” in Step S 258 , the process proceeds to Step S 259 . On the other hand, in a case where it is determined that disable_rps_prediction_flag is not “1” and the index i is not “0” in Step S 258 , the process proceeds to Step S 260 . 
     The process of Steps S 259  to S 268  is similar to the process of Steps S 199  to S 208  illustrated in  FIG. 28 , and thus, the description thereof will be omitted. 
     Fourth Embodiment 
     (Configuration Example of Encoding Device According to Fourth Embodiment) 
       FIG. 36  is a block diagram that illustrates an example of the configuration of an encoding device, to which the present technology is applied, according to the fourth embodiment. 
     Here, the same reference numeral is assigned to each configuration illustrated in  FIG. 36  that is the same as the configuration illustrated in  FIG. 3 , and the description thereof to be repeated will be omitted. 
     The configuration of the encoding device  230  illustrated in  FIG. 36  is different from the configuration of the encoding device  10  illustrated in  FIG. 3  in that an encoding unit  231  is arranged instead of the encoding unit  11 , and a setting unit  232  is arranged instead of the setting unit  12 . The encoding device  230 , in accordance with the type of slice within the picture, does not set information relating to a reference image that is not necessary for the type of slice. 
     More specifically, an image that is configured in units of frames is input to the encoding unit  231  of the encoding device  230  as an input signal. The encoding unit  231  codes the input signal in accordance with the HEVC system by referring to an RPS, a PPS, and the like supplied from the setting unit  232 . At this time, as is necessary, the encoding unit  231  performs a weighted prediction (Weighted Prediction) for the reference image in the inter prediction. 
     Here, the weighted prediction is a process of generating a predicted image by weighting a reference image. More specifically, for example, in a case where decoded images of two frames Y.sub.1 and Y.sub.0 prior to a current coding frame X in coding order are used as reference images, in the weighted prediction, a predicted image X′ of a frame X is acquired using the following Equation (3).
 
 X′=w   0   ×Y   0   +w   0   ×Y   1   +d   (3)
 
     Here, in Equation (3), w 0  and w 1  are weighting coefficients, and d is an offset value. These weighting coefficients and the offset value are transmitted with being included in the coded stream. 
     By performing the weighted prediction, even in a case where a change in the luminance occurs between the reference image and the current coding image due to fade-in, fade-out, cross-fade, or the like, a difference between the predicted image and the current coding image can be reduced. As a result, the coding efficiency can be improved. 
     In contrast, in a case where the weighted prediction is not performed, a change in the luminance that occurs between the reference image and the current coding image due to fade-in, fade-out, cross-fade, and the like directly becomes a difference between the predicted image and the current coding image, whereby the coding efficiency is degraded. 
     The encoding unit  231  supplies coded data acquired as a result of the coding process to the setting unit  232 . 
     The setting unit  232 , similar to the setting unit  12  illustrated in  FIG. 3 , sets the RPS that does not include inter_ref_pic_set_prediction_flag but include the reference image specifying information and the RPS that includes inter_ref_pic_set_prediction_flag and the reference image specifying information or delta_idx_minus1. The setting unit  232 , similar to the setting unit  12 , assigns an index to each RPS. 
     The setting unit  232  sets the SPS including the RPS, the PPS, and the like. The setting unit  232  supplies the RPS&#39;s to which the indexes are assigned and the PPS to the encoding unit  231 . The setting unit  232  generates a coded stream based on the SPS and the PPS, which have been set, and the coded data supplied from the encoding unit  231 . The setting unit  232  supplies the coded stream to the transmission unit  13 . 
     (Configuration Example of Encoding Unit) 
       FIG. 37  is a block diagram that illustrates an example of the configuration of the encoding unit  231  illustrated in  FIG. 36 . 
     Here, the same reference numeral is assigned to each configuration illustrated in  FIG. 37  that is the same as the configuration illustrated in  FIG. 4 , and the description thereof to be repeated will be omitted. 
     The configuration of the encoding unit  231  illustrated in  FIG. 37  is different from the configuration of the encoding unit  11  illustrated in  FIG. 4  in that a motion prediction/compensation unit  251  is arranged instead of the motion prediction/compensation unit  47 , and a lossless encoding unit  252  is arranged instead of the lossless encoding unit  36 . 
     The motion prediction/compensation unit  251 , based on the PPS supplied from the setting unit  232  illustrated in  FIG. 36 , performs a motion prediction/compensation process using a weighted prediction of all the inter prediction modes that are candidates. More specifically, the motion prediction/compensation unit  251  detects motion vectors of all the inter prediction modes that are candidates based on the image supplied from the screen rearrangement buffer  32  and the reference image read from the frame memory  44  through the switch  45 . Then, the motion prediction/compensation unit  251  performs a compensation process for the reference image based on the detected motion vector. 
     Then, the motion prediction/compensation unit  251  calculates weighting information that is configured by a weighting coefficient and an offset value in the weighted prediction. The motion prediction/compensation unit  251  serves as a generation unit and performs the weighted prediction for the reference image after the compensation process based on the calculated weighting information, thereby generating a predicted image. 
     At this time, the motion prediction/compensation unit  251 , similar to the motion prediction/compensation unit  47  illustrated in  FIG. 4 , calculates cost function values for all the inter prediction modes that are candidates based on the image supplied from the screen rearrangement buffer  32  and the predicted images. Then, the motion prediction/compensation unit  251 , similar to the motion prediction/compensation unit  47 , determines an inter prediction mode of which the cost function mode is the minimal as the optimal inter prediction mode. 
     Then, the motion prediction/compensation unit  251 , similar to the motion prediction/compensation unit  47 , supplies a predicted image corresponding to the cost function value of the optimal inter prediction mode to the predicted image selection unit  48 . In addition, in a case where the motion prediction/compensation unit  251  is notified of the selection of the predicted image generated in the optimal inter prediction mode from the predicted image selection unit  48 , the motion prediction/compensation unit  251  outputs the inter prediction mode information, the corresponding motion vector, the weighting information, and the like to the lossless encoding unit  252 . In addition, the motion prediction/compensation unit  251  outputs the reference image specifying information to the reference image setting unit  49 . 
     The lossless encoding unit  252  generates a slice type that represents the type of the slice of the current coding image based on the PPS supplied from the setting unit  232  illustrated in  FIG. 36 . In addition, the lossless encoding unit  252 , similar to the lossless encoding unit  36  illustrated in  FIG. 4 , acquires the intra prediction mode information from the intra prediction unit  46 . Furthermore, the lossless encoding unit  252  acquires the inter prediction mode information, the motion vector, the weighting information, and the like from the motion prediction/compensation unit  251 . In addition, the lossless encoding unit  252 , similar to the lossless encoding unit  36 , acquires the index of the RPS or the RPS and the like from the reference image setting unit  49  and acquires quantization parameters from the rate control unit  50 . 
     In addition, the lossless encoding unit  252 , similar to the lossless encoding unit  36 , acquires a storage flag, an index or an offset, and type information from the adaptive offset filter  42  as offset filter information and acquires a filter coefficient from the adaptive loop filter  43 . 
     The lossless encoding unit  252 , similar to the lossless encoding unit  36 , performs lossless coding of the quantized coefficient that is supplied from the quantization unit  35 . In addition, the lossless encoding unit  252  performs lossless coding of the quantization parameters, the offset filter information, and the filter coefficient such as the slice type, the intra prediction mode information or the inter prediction mode information, the motion vector, the weighting information, and the index of the RPS or the RPS as coding information. 
     The lossless encoding unit  252  adds the coding information that has been coded in a lossless manner to the coefficient that has been coded in a lossless manner as a slice header, thereby generating coded data. The lossless encoding unit  252  supplies the coded data to the accumulation buffer  37  so as to be stored therein. 
     (Example of Syntax of PPS) 
       FIGS. 38 and 39  are diagrams that illustrate examples of the syntax of the PPS that is set by the setting unit  232  illustrated in  FIG. 36 .  FIGS. 40 and 41  are diagrams that illustrate examples of the syntax of a PPS in a conventional HEVC system. 
     As illustrated in the sixth line in  FIG. 38 , in the PPS that is set by the setting unit  232 , a unification flag unified_slice_type_flag representing whether or not the types of all the slices within a corresponding picture are identical is included. In addition, as illustrated in the seventh and eighth lines, in a case where the unification flag is “1”, in the PPS, an I flag (all_intra_slice_flag) representing whether or not the types of all the slices within a corresponding picture are I slices is included. 
     In addition, as illustrated in the ninth and tenth lines, in a case where the I flag is not “1”, in other words, in a case where a P slice or a B slice is included within the picture, in the PPS, a B-not-present flag no_b_slice_flag representing whether or not a B slice is present within a corresponding picture is included. 
     As illustrated in the 11th and 12th lines, in a case where the I flag is not “1”, in the PPS, an RPSL0 number num_ref_idx_l0_default_active_minus1 that is a maximal number of the RPS&#39;s in a forward prediction (L0 prediction) using a reference image of which the display time is earlier than that of a corresponding picture is included as information relating to a reference image. 
     As illustrated in the 13th and 14th lines, in a case where the B-not-present flag is “0”, in other words, in a case where a B slice is included within the picture, in the PPS, an RPSL1 number (num_ref_idx_l1_default_active_minus1) that is a maximal number of the RPS&#39;s in a backward prediction (L1 prediction) using a reference image of which the display time is later than that of a corresponding picture is included as the information relating to a reference image. 
     As illustrated in the 25th and 26th lines, in a case where the I flag is not “1”, in the PPS, a P prediction flag weighted_pred_flag representing whether or not a weighted prediction is performed for the P slice is included as the information relating to a reference image. In addition, in a case where the B-not-present flag is not “1”, in the PPS, a B prediction flag weighted_bipred_flag representing whether or not a weighted prediction is performed for the B slice is included as the information relating to a reference image. 
     As above, in the PPS illustrated in  FIGS. 38 and 39 , in a case where a corresponding picture is configured by only an I slice, the RPSL0 number, the RPSL1 number, the P prediction flag, and the B prediction flag are not set. In addition, in a case where a corresponding picture includes a slice other than the I slice, the RPSL1 number and the B prediction flag are not set. Accordingly, the coding efficiency can be improved compared to a case where the RPSL0 number, the RPSL1 number, the P prediction flag, and the B prediction flag are set for all the pictures regardless of the types of the slices within the pictures. 
     In addition, in the decoding device, in a case where the picture is configured by only an I slice, the RPSL0 number and the RPSL1 number are recognized to be “0”, and, in a case where the picture includes a slice other than the I slice, the RPSL1 number is recognized to be “0”. 
     In contrast, in the PPS of the conventional HEVC system illustrated in  FIGS. 40 and 41 , as illustrated in the sixth, seventh, 17th, and 18th lines in  FIG. 40 , the RPSL0 number, the RPSL1 number, the P prediction flag, and the B prediction flag are set regardless of the type of the slice within the picture. 
     In addition, in a case where the picture is configured by only a B slice, the P prediction flag may be configured not to be set. 
     (Example of Syntax of Slice Header) 
       FIGS. 42 to 44  are diagrams that illustrate examples of the syntax of the slice header that is added by the lossless encoding unit  252  illustrated in  FIG. 37 . In addition,  FIGS. 45 to 47  are diagrams that illustrate examples of the syntax of the slice header in the conventional HEVC system. 
     As illustrated in the second line in  FIG. 42 , in the slice header added to the lossless encoding unit  252 , a first flag first_slice_in_pic_flag representing whether a corresponding slice is the first flag within the picture is included. In addition, as illustrated in the 11th and 12th lines, in a case where the unification flag is “0” or in a case where the unification flag is “1” and the first flag is “0”, in the slice header, the slice type slice_type of a corresponding slice is included. 
     In other words, in the slice header illustrated in  FIGS. 42 to 44 , in a case where the types of slices within the picture are not the same or in a case where the types of slices within the picture are the same and a corresponding slice is the first slice within the picture, the slice type is set. 
     However, in the slice header illustrated in  FIGS. 42 to 44 , in a case where the types of the slices within the picture are the same, and a corresponding slice is a slice other than the first slice within the picture, the slice type is not set. In such a case, the slice type included in the slice header is regarded as the slice type of a slice other than the first slice. 
     Accordingly, the coding efficiency can be improved compared to a case where the slice types of all the slices are set regardless whether or not the slice types of all the slices within the picture are the same. 
     In contrast, in a slice header of the conventional HEVC system illustrated in  FIGS. 45 to 47 , as illustrated in the 11th line in  FIG. 45 , the slice types of all the slices are set regardless whether or not the slice types of all the slices within the picture are the same. 
     (Description of Process of Encoding Device) 
       FIG. 48  is a flowchart that illustrates a generation process performed by the encoding device  230  illustrated in  FIG. 36 . 
     In Step S 281  illustrated in  FIG. 48 , the setting unit  232  of the encoding device  230  performs the RPS setting process illustrated in  FIG. 11 . In Step S 282 , the encoding unit  231  performs a coding process for coding an image, which is configured in units of frames, input from the outside as an input signal in accordance with the HEVC system. This coding process will be described later in detail with reference to  FIGS. 49 and 50  to be described later. 
     In Step S 283 , the setting unit  232  sets the SPS that includes the RPS to which the index is assigned. In Step S 284 , the setting unit  232  performs a PPS setting process for setting the PPS. This PPS setting process will be described later in detail with reference to  FIG. 51  to be described later. 
     The process of Steps S 285  and S 286  is similar to the process of Steps S 15  and S 16  illustrated in  FIG. 10 , and thus, the description thereof will be omitted. 
       FIGS. 49 and 50  represent a flowchart that illustrates the coding process of Step S 282  illustrated in  FIG. 48  in detail. 
     The process of Steps S 301  and S 302  illustrated in  FIG. 49  is similar to the process of Steps S 31  and S 32  illustrated in  FIG. 12 , and thus, the description thereof will be omitted. 
     In Step S 303 , the motion prediction/compensation unit  251  determines whether to perform a weighted prediction based on the P prediction flag or the B prediction flag included in the PPS that is supplied from the setting unit  232  illustrated in  FIG. 36 . 
     More specifically, in a case where the current coding image is the P slice, when the P prediction flag is “1”, the motion prediction/compensation unit  251  determines to perform the weighted prediction. In addition, in a case where the current coding image is the B slice, when the B prediction flag is “1”, the motion prediction/compensation unit  251  determines to perform the weighted prediction. Furthermore, in a case where the current coding image is the I slice, the process of Step S 303  is skipped, and the process proceeds to Step S 304 . 
     In a case where the weighted prediction is determined to be performed in Step S 303 , in Step S 304 , the intra prediction unit  46  performs an intra prediction process of all the intra prediction modes that are candidates. In addition, the intra prediction unit  46  calculates cost function values for all the intra prediction modes that are candidates based on the image read from the screen rearrangement buffer  32  and the predicted image generated as a result of the intra prediction process. Then, the intra prediction unit  46  determines an intra prediction mode of which the cost function value is the minimal as an optimal intra prediction mode. The intra prediction unit  46  supplies the predicted image generated in the optimal intra prediction mode and a corresponding cost function value to the predicted image selection unit  48 . 
     In addition, the motion prediction/compensation unit  251  performs a motion prediction/compensation process using weighted predictions of all the inter prediction modes that are candidates. In addition, the motion prediction/compensation unit  251  calculates cost function values for all the inter prediction modes that are the candidates based on the image supplied from the screen rearrangement buffer  32  and the predicted images and determines an inter prediction mode of which the cost function value is the minimal as an optimal inter prediction mode. Then, the motion prediction/compensation unit  251  supplies the cost function value of the optimal inter prediction mode and a corresponding predicted image to the predicted image selection unit  48 . 
     However, in a case where the current coding image is the I slice, the motion prediction/compensation process is not performed. After the process of Step S 304 , the process proceeds to Step S 306 . 
     On the other hand, in a case where a weighted prediction is determined not to be performed in Step S 303 , in Step S 305 , the intra prediction unit  46  performs the same process as that of Step S 304 . 
     In addition, the motion prediction/compensation unit  251  performs a motion prediction/compensation process for all the inter prediction modes that are the candidates. Furthermore, the motion prediction/compensation unit  251  calculates cost function values for all the inter prediction modes that are the candidates based on the image supplied from the screen rearrangement buffer  32  and the predicted images and determines an inter prediction mode of which the cost function value is the minimal as an optimal inter prediction mode. Then, the motion prediction/compensation unit  251  supplies the cost function value of the optimal inter prediction mode and a corresponding predicted image to the predicted image selection unit  48 . Then, the process proceeds to Step S 306 . 
     The process of Steps S 306  to S 308  is similar to the process of Steps S 34  to S 36  illustrated in  FIG. 12 , and thus, the description thereof will be omitted. 
     After the process of Step S 308 , in Step S 309 , the motion prediction/compensation unit  251  determines whether or not a weighted prediction has been performed in the motion prediction/compensation process. In a case where it is determined that the weighted prediction has been performed in the motion prediction/compensation process in Step S 309 , in Step S 310 , the motion prediction/compensation unit  251  supplies the weighting information of the weighted prediction to the lossless encoding unit  252 . Then, the process proceeds to Step S 311 . 
     The process of Steps S 311  to S 322  is similar to the process of Steps S 37  to S 48  illustrated in  FIGS. 12 and 13 , and thus, the description thereof will be omitted. 
     In Step S 323  illustrated in  FIG. 50 , the lossless encoding unit  252  determines whether the unification flag included in the PPS supplied from the setting unit  232  illustrated in  FIG. 36  is “0” or whether or not the unification flag and the first flag are “1”. 
     In a case where it is determined that the unification flag is “0” or the unification flag and the first flag are “1” in Step S 323 , in Step S 324 , the lossless encoding unit  252  generates a slice type of the current coding image. Then, the process proceeds to Step S 325 . 
     On the other hand, in a case where it is determined that the unification flag is not “0” and the unification flag and the first flag are not “1” in Step S 323 , the process proceeds to Step S 325 . 
     In Step S 325 , the lossless encoding unit  252  performs lossless coding of the quantization parameters supplied from the rate control unit  50 , the offset filter information, and the filter coefficient such as the slice type, the intra prediction mode information or the inter prediction mode information, the motion vector, the weighting information, and the index of the RPS or the RPS as coding information. 
     The process of Steps S 326  to S 329  is similar to the process of Steps S 50  to S 53  illustrated in  FIG. 13 , and thus, the description thereof will be omitted. 
       FIG. 51  is a flowchart that illustrates the PPS setting process of Step S 284  illustrated in  FIG. 48  in detail. This PPS setting process is performed in units of pictures. 
     In Step S 331  illustrated in  FIG. 51 , the setting unit  232  determines whether or not the types of all the slices within the picture are the same. In a case where it is determined that the types of all the slices within the picture are the same in Step S 331 , in Step S 332 , the setting unit  232  sets the unification flag to “1” and includes the set unification flag in the PPS. 
     In Step S 333 , the setting unit  232  determines whether or not the types of all the slices within the picture are the I slices. In a case where it is determined that the types of all the slices within the picture are the I slices in Step S 333 , in Step S 334 , the setting unit  232  sets the I flag to “1” and includes the set I flag in the PPS, and the process proceeds to Step S 337 . 
     On the other hand, in a case where it is determined that the types of all the slices within the picture are not the I slices in Step S 333 , in Step S 335 , the setting unit  232  sets the I flag to “0” and includes the set I flag in the PPS, and the process proceeds to Step S 337 . 
     On the other hand, in a case where it is determined that the types of all the slices within the picture are not the same in Step S 331 , in Step S 336 , the setting unit  232  sets the I flag to “0” and includes the set I flag in the PPS, and the process proceeds to Step S 337 . 
     In Step S 337 , the setting unit  232  determines whether or not the I flag is “1”. In a case where it is determined that the I flag is not “1” in Step S 337 , in Step S 338 , the setting unit  232  sets the RPSL0 number and the P prediction flag included in the PPS and includes the RPSL0 number and the P prediction flag that have been set in the PPS. 
     In Step S 339 , the setting unit  232  determines whether or not a B slice is included within the picture. In a case where it is determined that the B slice is included within the picture in Step S 339 , in Step S 340 , the setting unit  232  sets the B-not-present flag included in the PPS to “0” and includes the set flag in the PPS. In Step S 341 , the setting unit  232  sets the RPSL1 number and the B prediction flag included in the PPS and includes the RPSL1 number and the B prediction flag that have been set in the PPS. Then, the process is returned to Step S 284  illustrated in  FIG. 48  and proceeds to Step S 285 . 
     On the other hand, in a case where it is determined that the B slice is not included within the picture in Step S 339 , in Step S 342 , the setting unit  232  sets the B-not-present flag to “1” and includes the set flag in the PPS. Then, the process is returned to Step S 284  illustrated in  FIG. 48  and proceeds to Step S 285 . 
     In addition, in a case where it is determined that the I flag is “1” in Step S 337 , the process is returned to Step S 284  illustrated in  FIG. 48  and proceeds to Step S 285 . 
     As above, since the encoding device  230  sets the information relating to a reference image in accordance with the types of slices within the picture, the amount of information relating to a reference image is reduced, and accordingly, the coding efficiency can be improved. In addition, since the encoding device  230  sets the slice type depending on whether the types of all the slices within the picture are the same, the amount of information of the slice type is reduced, and accordingly, the coding efficiency can be improved. 
     (Configuration Example of Decoding Device According to Fourth Embodiment) 
       FIG. 52  is a block diagram that illustrates an example of the configuration of the decoding device, to which the present technology is applied, according to the fourth embodiment that decodes a coded stream transmitted from the encoding device  230  illustrated in  FIG. 36 . 
     Here, the same reference numeral is assigned to each configuration illustrated in  FIG. 52  that is the same as the configuration illustrated in  FIG. 15 , and the description thereof to be repeated will be omitted. 
     The configuration of the decoding device  270  illustrated in  FIG. 52  is different from the configuration illustrated in  FIG. 15  in that a decoding unit  271  is arranged instead of the decoding unit  113 . The decoding device  270  performs a weighted prediction when a motion compensation process is performed as is necessary. 
     More specifically, the decoding unit  271  of the decoding device  270  decodes the coded data supplied from the extraction unit  112  in accordance with the HEVC system based on inter_ref_pic_set_prediction_flag of each RPS and delta_idx_minus1 or the reference image specifying information supplied from the extraction unit  112 . At this time, the decoding unit  271  refers to information other than the RPS that is included in the SPS, the PPS, and the like as is necessary. In addition, the decoding unit  271 , as is necessary, performs a weighted prediction when the motion compensation process is performed. The decoding unit  271  outputs an image acquired as a result of the decoding as an output signal. 
     (Configuration Example of Decoding Unit) 
       FIG. 53  is a block diagram that illustrates an example of the configuration of the decoding unit  271  illustrated in  FIG. 52 . 
     Here, the same reference numeral is assigned to each configuration illustrated in  FIG. 53  that is the same as the configuration illustrated in  FIG. 16 , and the description thereof to be repeated will be omitted. 
     The configuration of the decoding unit  271  illustrated in  FIG. 53  is different from the configuration illustrated in  FIG. 16  in that a lossless decoding unit  291  is arranged instead of the lossless decoding unit  132 , and a motion compensation unit  292  is arranged instead of the motion compensation unit  145 . 
     The lossless decoding unit  291  of the decoding unit  271 , similar to the lossless decoding unit  132  illustrated in  FIG. 16 , performs lossless decoding for the coded data supplied from the accumulation buffer  131 , thereby acquiring the quantized coefficients and the coding information. The lossless decoding unit  291 , similar to the lossless decoding unit  132 , supplies the quantized coefficients to the inverse quantization unit  133 . In addition, the lossless decoding unit  291  supplies the intra prediction mode information and the like as the coding information to the intra prediction unit  143  and supplies the motion vector, the inter prediction mode information, the weighting information, and the like to the motion compensation unit  292 . The lossless decoding unit  291 , similar to the lossless decoding unit  132 , supplies the RPS flag and the index of the RPS or the RPS as the coding information to the reference image setting unit  144 . 
     In addition, the lossless decoding unit  291 , similar to the lossless decoding unit  132 , supplies the intra prediction mode information or the inter prediction mode information as the coding information to the switch  146 . The lossless decoding unit  291 , similar to the lossless decoding unit  132 , supplies the offset filter information as the coding information to the adaptive offset filter  137  and supplies the filter coefficient to the adaptive loop filter  138 . 
     The motion compensation unit  292 , similar to the motion compensation unit  145  illustrated in  FIG. 16 , reads a reference image specified by the reference image specifying information from the frame memory  141  through the switch  142  based on the reference image specifying information supplied from the reference image setting unit  144 . 
     In addition, the motion compensation unit  292 , similar to the motion prediction/compensation unit  251  illustrated in  FIG. 37 , determines whether to perform a weighted prediction based on the P prediction flag or the B prediction flag that is included in the PPS that is supplied from the extraction unit  112 . 
     The motion compensation unit  292  serves as a generation unit and, in a case where it is determined to perform the weighted prediction, performs a motion compensation process using the weighted prediction of the optimal inter prediction mode represented by the inter prediction mode information by using the motion vector and the reference image. At this time, the motion compensation unit  292 , as is necessary, in a case where the slice of the current coding image is the P slice, refers to the RPSL0 number and, in a case where the slice of the current coding image is the B slice, refers to the RPSL0 number and the RPSL1 number. 
     On the other hand, in a case where the weighted prediction is determined not to be performed, the motion compensation unit  292 , similar to the motion compensation unit  145 , performs a motion compensation process of the optimal inter prediction mode. The motion compensation unit  292  supplies a predicted image generated as a result thereof to the switch  146 . 
     (Description of Process of Decoding Device) 
       FIG. 54  is a flowchart that illustrates a reception process performed by the decoding device  270  illustrated in  FIG. 52 . 
     The process of Steps S 351  to S 353  illustrated in  FIG. 54  is similar to the process of Steps S 111  to S 113  illustrated in  FIG. 17 , and thus, the description thereof will be omitted. 
     In Step S 354 , the decoding unit  271  performs a decoding process based on the RPS information of each RPS and the PPS that are supplied from the extraction unit  112 . This decoding process will be described in detail with reference to  FIG. 55  to be described later. Then, the process ends. 
       FIG. 55  is a flowchart that illustrates the decoding process of Step S 354  illustrated in  FIG. 54  in detail. 
     In Step S 361  illustrated in  FIG. 55 , the accumulation buffer  131  of the decoding unit  271  receives coded data, which is configured in units of frames” from the extraction unit  112  illustrated in  FIG. 52  and stores the received coded data. The accumulation buffer  131  supplies the stored coded data to the lossless decoding unit  291 . 
     In Step S 362 , the lossless decoding unit  291  performs lossless decoding of the coded data supplied from the accumulation buffer  131 , thereby acquiring the quantized coefficient and the coding information. The lossless decoding unit  291  supplies the quantized coefficient to the inverse quantization unit  133 . In addition, the lossless decoding unit  291  supplies the intra prediction mode information and the like as the coding information to the intra prediction unit  143  and supplies the motion vector, the inter prediction mode information, the weighting information, the RPS flag, the index of the RPS or the RPS, and the like to the motion compensation unit  292 . 
     In addition, the lossless decoding unit  291  supplies the intra prediction mode information as the coding information or the inter prediction mode information to the switch  146 . The lossless decoding unit  291  supplies the offset filter information as the coding information to the adaptive offset filter  137  and supplies the filter coefficient to the adaptive loop filter  138 . 
     The process of Steps S 363  to S 365  is similar to the process of Steps S 133  to S 135  illustrated in  FIG. 19 , and thus, the description thereof will be omitted. In Step S 366 , the motion compensation unit  292 , similar to the motion prediction/compensation unit  251  illustrated in  FIG. 37 , determines whether to perform a weighted prediction based on the P prediction flag or the B prediction flag included in the PPS that is supplied from the extraction unit  112  illustrated in  FIG. 52 . 
     In a case where the weighted prediction is determined to be performed in Step S 366 , in Step S 367 , the motion compensation unit  292  reads a reference image based on the reference image specifying information supplied from the reference image setting unit  144  and performs a motion compensation process using the weighted prediction of the optimal inter prediction mode represented by the inter prediction mode information by using the motion vector and the reference image. 
     At this time, the motion compensation unit  292 , as is necessary, in a case where the slice of the current coding image is the P slice, refers to the RPSL0 number and, in a case where the slice of the current coding image is the B slice, refers to the RPSL0 number and the RPSL1 number. The motion compensation unit  292  supplies a predicted image generated as a result thereof to the addition unit  135  through the switch  146 , and the process proceeds to Step S 370 . 
     On the other hand, in a case where the weighted prediction is determined not to be performed in Step S 366 , in Step S 368 , the motion compensation unit  292  reads a reference image based on the reference image specifying information supplied from the reference image setting unit  144  and performs a motion compensation process of the optimal inter prediction mode represented by the inter prediction mode information by using the motion vector and the reference image. The motion compensation unit  292  supplies a predicted image generated as a result thereof to the addition unit  135  through the switch  146 , and the process proceeds to Step S 370 . 
     The process of Steps S 369  to S 377  is similar to the process of Steps S 137  to S 145  illustrated in  FIG. 19 , and thus, the description thereof will be omitted. 
     As above, by setting the information relating to a reference image in accordance with the types of slices within the picture, the decoding device  270  can decode a coded stream having improved coding efficiency. 
     In addition, in the fourth embodiment, while the information relating to a reference image has been described as the RPSL0 number, the RPSL1 number, the P prediction flag, and the B prediction flag, the present technology is not limited thereto. 
     &lt;Application to Multiple Viewpoint Image Coding/Multiple Viewpoint Image Decoding&gt; 
     The series of processes described above may be applied to multiple viewpoint image coding and multiple viewpoint image decoding.  FIG. 56  is a diagram that illustrates an example of a multiple viewpoint image coding system. 
     As illustrated in  FIG. 56 , a multiple viewpoint image includes images of a plurality of viewpoints, and an image of a predetermined viewpoint out of the plurality of viewpoints is designated as an image of a base view. The image of each viewpoint other than the image of the base view is handled as an image of a non-base view. 
     In a case where multiple viewpoint image coding as illustrated in  FIG. 56  is performed, for each view (the same view), a difference between the quantization parameters may be taken. 
     (1) base-view: 
     (1-1) dQP(base view)=Current_CU_QP(base view)−LCU_QP(base view) 
     (1-2) dQP(base view)=Current_CU_QP(base view)−Previsous_CU_QP(base view) 
     (1-3) dQP(base view)=Current_CU_QP(base view)−Slice_QP(base view) 
     (2) non-base-view: 
     (2-1) dQP(non-base view)=Current_CU_QP(non-base view)−LCU_QP(non-base view) 
     (2-2) dQP(non-base view)=CurrentQP(non-base view)−PrevisousQP(non-base view) 
     (2-3) dQP(non-base view)=Current_CU_QP(non-base view)−Slice_QP(non-base view) 
     In a case where the multiple viewpoint image coding is performed, for each view (different views), a difference between the quantization parameters may be taken. 
     (3) base-view/non-base view: 
     (3-1) dQP(inter-view)=Slice_QP(base view)−Slice_QP(non-base view) 
     (3-2) dQP(inter-view)=LCU_QP(base view)−LCU_QP(non-base view) 
     (4) non-base view/non-base view: 
     (4-1) dQP(inter-view)=Slice_QP(non-base view i)−Slice_QP(non-base view j) 
     (4-2) dQP(inter-view)=LCU_QP(non-base view i)−LCU_QP(non-base view j) 
     In such a case, (1) to (4) described above may be used in a combinational manner. For example, in a non-base view, a technique (combining 3-1 and 2-3) for taking a difference between the quantization parameters of the base view and the non-base view at a slice level and a technique (combining 3-2 and 2-1) for taking a difference between the quantization parameters of the base view and the non-base view at the LCU level may be considered. In this way, by repeatedly applying the difference, also in a case where the multiple viewpoint coding is performed, the coding efficiency can be improved. 
     Similar to the above-described technique, for each dQP described above, a flag used for identifying whether or not a dQP having a value other than “0” is present may be set. 
     &lt;Multiple Viewpoint Image Encoding Device&gt; 
       FIG. 57  is a diagram that illustrates a multiple viewpoint image encoding device that performs the multiple viewpoint image coding described above. As illustrated in  FIG. 57 , the multiple viewpoint image encoding device  600  includes an encoding unit  601 , an encoding unit  602 , and a multiplexer  603 . 
     The encoding unit  601  codes a base view image, thereby generating a base view image coded stream. In addition, the encoding unit  602  codes a non-base view image, thereby generating a non-base view image coded stream. The multiplexer  603  multiplexes the base view image coded stream generated by the encoding unit  601  and the non-base view image coded stream generated by the encoding unit  602 , thereby generating a multiple view point image coded stream. 
     The encoding device  10  ( 150  and  190 ) may be applied to the encoding unit  601  and the encoding unit  602  of this multiple viewpoint image encoding device  600 . In such a case, the multiple viewpoint image encoding device  600  sets a difference between the quantization parameter set by the encoding unit  601  and the quantization parameter set by the encoding unit  602  and transmits the set difference. 
     &lt;Multiple Viewpoint Image Decoding Device&gt; 
       FIG. 58  is a diagram that illustrates a multiple viewpoint image decoding device that performs the multiple viewpoint image decoding described above. As illustrated in  FIG. 58 , the multiple viewpoint image decoding device  610  includes a demultiplexer  611 , a decoding unit  612 , and a decoding unit  613 . 
     The demultiplexer  611  demultiplexes a multiple viewpoint image coded stream acquired by multiplexing the base view image coded stream and the non-base view image coded stream, thereby extracting a base view image coded stream and a non-base view image coded stream. The decoding unit  612  decodes the base view image coded stream extracted by the demultiplexer  611 , thereby acquiring the base view image. The decoding unit  613  decodes the non-base view image coded stream extracted by the demultiplexer  611 , thereby acquiring the non-base view image. 
     The decoding device  110  ( 170  and  210 ) may be applied to the decoding unit  612  and the decoding unit  613  of this multiple view point image decoding device  610 . In such a case, the multiple viewpoint image decoding device  610  sets a quantization parameter based on a difference between the quantization parameter set by the encoding unit  601  and the quantization parameter set by the encoding unit  602  and performs inverse quantization. 
     3&lt;Application to Hierarchical Image Coding/Hierarchical Image Decoding&gt; 
     The series of processes described above may be applied to hierarchical image coding and hierarchical image decoding.  FIG. 59  is a diagram that illustrates an example of a hierarchical image coding system. 
     As illustrated in  FIG. 59 , a hierarchical image includes images of a plurality of hierarchies (resolutions), and an image of a predetermined hierarchy out of the plurality of resolutions is designated as an image of a base layer. Images of hierarchies other than the image of the base layer are handled as images of non-base layers. 
     In a case where the hierarchical image coding (spatial scalability) as illustrated in  FIG. 59  is performed, in each layer (the same layer), a difference between quantization parameters may be taken. 
     (1) base-layer: 
     (1-1) dQP(base layer)=Current_CU_QP(base layer)−LCU_QP(base layer) 
     (1-2) dQP(base layer)=Current_CU_QP(base layer)−Previsous_CU_QP(base layer) 
     (1-3) dQP(base layer)=Current_CU_QP(base layer)−Slice_QP(base layer) 
     (2) non-base-layer: 
     (2-1) dQP(non-base layer)=Current_CU_QP(non-base layer)−LCU_QP(non-base layer) 
     (2-2) dQP(non-base layer)=CurrentQP(non-base layer)−PrevisousQP(non-base layer) 
     (2-3) dQP(non-base layer)=Current_CU_QP(non-base layer)−Slice_QP(non-base layer) 
     In a case where the hierarchical coding is performed, in each layer (different layers), a difference between quantization parameters may be taken. 
     (3) base-layer/non-base layer: 
     (3-1) dQP(inter-layer)=Slice_QP(base layer)−Slice_QP(non-base layer) 
     (3-2) dQP(inter-layer)=LCU_QP(base layer)−LCU_QP(non-base layer) 
     (4) non-base layer/non-base layer: 
     (4-1) dQP(inter-layer)=Slice_QP(non-base layer i)−Slice_QP(non-base layer j) 
     (4-2) dQP(inter-layer)=LCU_QP(non-base layer i)−LCU_QP(non-base layer j) 
     In such a case, (1) to (4) described above may be used in a combinational manner. For example, in a non-base layer, a technique (combining 3-1 and 2-3) for taking a difference between the quantization parameters of the base layer and the non-base layer at the slice level and a technique (combining 3-2 and 2-1) for taking a difference between the quantization parameters of the base layer and the non-base layer at the LCU level may be considered. In this way, by repeatedly applying the difference, also in a case where the hierarchical coding is performed, the coding efficiency can be improved. 
     Similar to the above-described technique, for each dQP described above, a flag used for identifying whether or not a dQP having a value other than “0” is present may be set. 
     &lt;Hierarchical Image Encoding Device&gt; 
       FIG. 60  is a diagram that illustrates a hierarchical image encoding device that performs the hierarchical image coding described above. As illustrated in  FIG. 60 , the hierarchical image encoding device  620  includes an encoding unit  621 , an encoding unit  622 , and a multiplexer  623 . 
     The encoding unit  621  codes a base layer image, thereby generating a base layer image coded stream. In addition, the encoding unit  622  codes a non-base layer image, thereby generating a non-base layer image coded stream. The multiplexer  623  multiplexes the base layer image coded stream generated by the encoding unit  621  and the non-base layer image coded stream generated by the encoding unit  622 , thereby generating a hierarchical image coded stream. 
     The encoding device  10  ( 150  and  190 ) may be applied to the encoding unit  621  and the encoding unit  622  of this hierarchical image encoding device  620 . In such a case, the hierarchical image encoding device  620  sets a difference between the quantization parameter set by the encoding unit  621  and the quantization parameter set by the encoding unit  622  and transmits the set difference. 
     &lt;Hierarchical Image Decoding Device&gt; 
       FIG. 61  is a diagram that illustrates a hierarchical image decoding device that performs the hierarchical image decoding described above. As illustrated in  FIG. 61 , the hierarchical image decoding device  630  includes a demultiplexer  631 , a decoding unit  632 , and a decoding unit  633 . 
     The demultiplexer  631  demultiplexes a hierarchical image coded stream acquired by multiplexing the base layer image coded stream and the non-base layer image coded stream, thereby extracting a base layer image coded stream and a non-base layer image coded stream. The decoding unit  632  decodes the base layer image coded stream extracted by the demultiplexer  631 , thereby acquiring the base layer image. The decoding unit  633  decodes the non-base layer image coded stream extracted by the demultiplexer  631 , thereby acquiring the non-base layer image. 
     The decoding device  110  ( 170  and  210 ) may be applied to the decoding unit  632  and the decoding unit  633  of this hierarchical image decoding device  630 . In such a case, the hierarchical image decoding device  630  sets a quantization parameter based on a difference between the quantization parameter set by the encoding unit  621  and the quantization parameter set by the encoding unit  622  and performs inverse quantization. 
     &lt;Description of Computer to which Present Technology is Applied&gt; 
     The series of processes described above may be performed by hardware or software. In a case where the series of processes is performed by software, a program that configures the software is installed to a computer. Here, the computer includes a computer that is built into dedicated hardware, a computer that can execute various functions by having various programs installed thereto such as a general-purpose computer, and the like. 
       FIG. 62  is a block diagram that illustrates an example of the hardware configuration of the computer that executes the series of processes described above in accordance with a program. 
     In the computer, a CPU (Central Processing Unit)  801 , a ROM (Read Only Memory)  802 , and a RAM (Random Access Memory)  803  are interconnected through a bus  804 . 
     In addition, an input/output interface  805  is connected to the bus  804 . To the input/output interface  805 , an input unit  806 , an output unit  807 , a storage unit  808 , a communication unit  809 , and a drive  810  are connected. 
     The input unit  806  is configured by a keyboard, a mouse, a microphone, and the like. The output unit  807  is configured by a display, a speaker, and the like. The storage unit  808  is configured by a hard disk, a non-volatile memory, or the like. The communication unit  809  is configured by a network interface or the like. The drive  810  drives a removable medium  811  such as a magnetic disk, an optical disc, a magneto-optical disk, or a semiconductor disk. 
     In the computer configured as described above, the CPU  801  performs the series of processes described above, for example, by loading a program stored in the storage unit  808  into the RAM  803  through the input/output interface  805  and the bus  804  and executing the program. 
     The program executed by the computer (CPU  801 ), for example, may be provided by being recorded on the removable medium  811  as a package medium. In addition, the program may be provided through a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting. 
     In the computer, the program can be installed to the storage unit  808  through the input/output interface  805  by loading the removable medium  811  into the drive  810 . In addition, the program may be received by the communication unit  809  through a wired or wireless transmission medium and be installed to the storage unit  808 . Furthermore, the program may be installed in advance to the ROM  802  or the storage unit  808 . 
     In addition, the program executed by the computer may be a program that performs the process in a time series in the sequence described here or may be a program that performs the process in a parallel manner or at necessary timing such as timing when the program is called. 
     &lt;Configuration Example of Television Apparatus&gt; 
       FIG. 63  illustrates the schematic configuration of a television apparatus to which the present technology is applied. The television apparatus  900  includes: an antenna  901 ; a tuner  902 ; a demultiplexer  903 ; a decoder  904 ; a video signal processing unit  905 ; a display unit  906 ; an audio signal processing unit  907 ; a speaker  908 ; and an external interface unit  909 . In addition, the television apparatus  900  includes a control unit  910 , a user interface unit  911 , and the like. 
     The tuner  902  selects a desired channel from broadcast wave signals received by the antenna  901 , performs demodulation, and outputs an acquired coded bitstream to the demultiplexer  903 . 
     The demultiplexer  903  extracts a packet of a video or an audio of a program that is a viewing target from the coded bitstream and outputs data of the extracted packet to the decoder  904 . In addition, the demultiplexer  903  supplies a packet of data such as an EPG (Electronic Program Guide) or the like to the control unit  910 . Furthermore, in a case where scrambling is performed, the scrambling is released using a demultiplexer or the like. 
     The decoder  904  performs a decoding process of a packet and outputs video data generated by the decoding process to the video signal processing unit  905  and outputs audio data to the audio signal processing unit  907 . 
     The video signal processing unit  905  performs noise removal, video processing according to a user setting, and the like for the video data. The video signal processing unit  905  generates video data of a program that is to be displayed on the display unit  906 , image data according to a process that is based on an application supplied through a network, and the like. In addition, the video signal processing unit  905  generates video data for displaying a menu screen such as an item selection screen and the like and overlaps the generated video data on the video data of the program. The video signal processing unit  905  generates a drive signal based on the video data generated as above and drives the display unit  906 . 
     The display unit  906  drives a display device (for example, a liquid crystal display device or the like) based on the drive signal supplied from the video signal processing unit  905 , thereby displaying a video of a program and the like. 
     The audio signal processing unit  907  performs a predetermined process such as noise removal for the audio data, performs a D/A conversion process of audio data after the process or an amplification process thereof, and supplies resultant data to the speaker  908 , thereby performing audio output. 
     The external interface unit  909  is an interface used for a connection to an external device or a network and transmits/receives data such as video data or audio data. 
     The user interface unit  911  is connected to the control unit  910 . The user interface unit  911  is configured by an operation switch, a remote control signal reception unit, and the like and supplies an operation signal according to a user operation to the control unit  910 . 
     The control unit  910  is configured by a CPU (Central Processing Unit), a memory, and the like. The memory stores a program executed by the CPU, various kinds of data that is necessary for the process performed by the CPU, EPG data, data acquired through a network, and the like. The program that is stored in the memory is read and executed by the CPU at predetermined timing such as start-up of the television apparatus  900 . By executing the program, the CPU performs control of each unit such that the television apparatus  900  operates in accordance with a user operation. 
     In addition, in the television apparatus  900 , in order to connect the tuner  902 , the demultiplexer  903 , the video signal processing unit  905 , the audio signal processing unit  907 , the external interface unit  909 , and the like to the control unit  910 , a bus  912  is disposed. 
     In the television apparatus configured in this way, the function of the decoding device (decoding method) according to the present application is implemented in the decoder  904 . Accordingly, a coded stream in which the amount of information relating to the information specifying a reference image is reduced can be decoded. 
     &lt;Configuration Example of Mobile Phone&gt; 
       FIG. 64  illustrates the schematic configuration of a mobile phone to which the present technology is applied. The mobile phone  920  includes: a communication unit  922 ; an audio codec  923 ; a camera unit  926 ; an image processing unit  927 ; a multiplexing/separating unit  928 ; a recording/reproducing unit  929 ; a display unit  930 ; and a control unit  931 . These are interconnected through the bus  933 . 
     In addition, the antenna  921  is connected to the communication unit  922 , and the speaker  924  and the microphone  925  are connected to the audio codec  923 . Furthermore, the operation unit  932  is connected to the control unit  931 . 
     The mobile phone  920  performs various operations such as transmission and reception of an audio signal, transmission and reception of an electronic mail and image data, image capturing, and data recording in various modes such as a voice call mode and a data communication mode. 
     In the voice call mode, an audio signal generated by the microphone  925  is converted into audio data or compressed by the audio codec  923 , and a resultant signal is supplied to the communication unit  922 . The communication unit  922  performs a modulation process, a frequency conversion process, and the like for the audio data, thereby generating a transmission signal. In addition, the communication unit  922  supplies a transmission signal to the antenna  921  so as to be transmitted to a base station not illustrated in the figure. Furthermore, the communication unit  922  performs an amplification process, a frequency conversion process, a demodulation process, and the like for a reception signal received by the antenna  921  and supplies acquired audio data to the audio codec  923 . The audio codec  923  performs data decompression of the audio data and converts the audio data into an analog audio signal and outputs a resultant signal to the speaker  924 . 
     In addition, in the data communication mode, in a case where a mail is transmitted, the control unit  931  receives character data input by an operation for the operation unit  932  and displays the input characters on the display unit  930 . Furthermore, the control unit  931  generates mail data based on a user&#39;s instruction from the operation unit  932  and supplies the generated mail data to the communication unit  922 . The communication unit  922  performs a modulation process, a frequency conversion process, and the like for the mail data and transmits an acquired transmission signal from the antenna  921 . In addition, the communication unit  922  performs an amplification process, a frequency conversion process, a demodulation process, and the like for the reception signal received by the antenna  921 , thereby restoring the mail data. This mail data is supplied to the display unit  930 , whereby the content of the mail is displayed. 
     In addition, the mobile phone  920  can store the received mail data in a storage medium using the recording/reproducing unit  929 . The storage medium may be an arbitrary rewritable storage medium. For example, the storage medium is a semiconductor memory such as a RAM or a built-in type flash memory, a hard disk, a magnetic disk, a magneto-optical disk, an optical disc, or a removable medium such as a USB memory or a memory card. 
     In the data communication mode, in a case where image data is transmitted, the image data generated by the camera unit  926  is supplied to the image processing unit  927 . The image processing unit  927  performs a coding process of the image data, thereby generating coded data. 
     The multiplexing/separating unit  928  multiplexes coded data generated by the image processing unit  927  and audio data supplied from the audio codec  923  in accordance with a predetermined system and supplies multiplexed data to the communication unit  922 . The communication unit  922  performs a modulation process, a frequency conversion process, and the like of the multiplexed data and transmits an acquired transmission signal from the antenna  921 . In addition, the communication unit  922  performs an amplification process, a frequency conversion process, a demodulation process, and the like for the reception signal received by the antenna  921 , thereby restoring the multiplexed data. This multiplexed data is supplied to the multiplexing/separating unit  928 . The multiplexing/separating unit  928  separates the multiplexed data and supplies coded data to the image processing unit  927  and supplies audio data to the audio codec  923 . The image processing unit  927  performs a decoding process of the coded data, thereby generating image data. This image data is supplied to the display unit  930 , whereby the received image is displayed. The audio codec  923  converts audio data into an analog audio signal and supplies the converted analog audio signal to the speaker  924 , thereby outputting the received audio. 
     In the mobile phone device configured in this way, the functions of the encoding device and the decoding device (a coding method and a decoding method) according to the present application are implemented in the image processing unit  927 . Accordingly, a coded stream in which the amount of information relating to information that specifies a reference image is reduced can be decoded. 
     &lt;Configuration Example of Recording and Reproducing Device&gt; 
       FIG. 65  illustrates the schematic configuration of a recording and reproducing device to which the present technology is applied. The recording and reproducing device  940 , for example, records audio data and video data of a received broadcast program on a recording medium and provides the recorded data for a user at timing according to a user&#39;s instruction. In addition, the recording and reproducing device  940 , for example, may acquire audio data and video data from another device and record the audio data and the video data on a recording medium. Furthermore, the recoding and reproducing device  940  decodes and outputs the audio data and the video data, which are recorded on the recording medium, whereby the display of an image or the output of an audio can be performed in a monitor device or the like. 
     The recording and reproducing device  940  includes: a tuner  941 ; an external interface unit  942 ; an encoder  943 ; an HDD (Hard Disk Drive) unit  944 ; a disk driver  945 ; a selector  946 ; a decoder  947 ; an OSD (On-Screen Display) unit  948 ; a control unit  949 ; and a user interface unit  950 . 
     The tuner  941  selects a desired channel from among broadcast signals received by an antenna not illustrated in the figure. The tuner  941  outputs a coded bitstream acquired by demodulating a reception signal of the desired channel to the selector  946 . 
     The external interface unit  942  is configured by at least one of an IEEE1394 interface, a network interface unit, a USB interface, a flash memory interface, and the like. The external interface unit  942  is an interface for a connection to an external device, a network, a memory card, or the like and performs data reception of video data, audio data, and the like to be recorded. 
     When the video data and the audio data supplied from the external interface unit  942  are not coded, the encoder  943  codes the video data and the audio data in accordance with a predetermined system and outputs a coded bitstream to the selector  946 . 
     The HDD unit  944  records content data such as videos and audios, various programs, other data, and the like on a built-in hard disk and reads the recorded data from the hard disk at the time of reproduction or the like. 
     The disk driver  945  performs signal recording and signal reproducing for a loaded optical disc. The optical disc, for example, is a DVD disc (a DVD-Video, a DVD-RAM, a DVD-R, a DVD-RW, a DVD+R, a DVD+RW, or the like), a Blu-ray (registered trademark) disc, or the like. 
     When a video or an audio is recorded, the selector  946  selects a coded bitstream supplied from the tuner  941  or the encoder  943  and supplies the selected code bitstream to one of the HDD unit  944  and the disk driver  945 . In addition, when a video or an audio is reproduced, the selector  946  supplies a coded bitstream output from the HDD unit  944  or the disk driver  945  to the decoder  947 . 
     The decoder  947  performs a decoding process of the coded bit stream. The decoder  947  supplies video data that is generated by performing the decoding process to the OSD unit  948 . In addition, the decoder  947  outputs audio data that is generated by performing the decoding process. 
     The OSD unit  948  generates video data used for displaying a menu screen such as an item selection menu or the like and outputs the generated video data so as to overlap the video data output from the decoder  947 . 
     The user interface unit  950  is connected to the control unit  949 . The user interface unit  950  is configured by an operation switch, a remote control signal reception unit, and the like and supplies an operation signal according to a user operation to the control unit  949 . 
     The control unit  949  is configured by using a CPU, a memory, and the like. The memory stores programs that are executed by the CPU and various kinds of data that is necessary for the process performed by the CPU. A program stored in the memory is read and executed by the CPU at predetermined timing such as the start-up of the recording and reproducing device  940 . The CPU executes programs, thereby performing control of each unit such that the recoding and reproducing device  940  operates in accordance with a user operation. 
     In the recoding and reproducing device configured in this way, the function of the decoding device (decoding method) according to the present application is implemented in the decoder  947 . Accordingly, a coded stream in which the amount of information relating to the information specifying a reference image is reduced can be decoded. 
     &lt;Configuration Example of Imaging Device&gt; 
       FIG. 66  is a diagram that illustrates an example of the schematic configuration of an imaging device to which the present technology is applied. The imaging device  960  images a subject and displays the image of the subject on a display unit or records the image of the subject on a recording medium as image data. 
     The imaging device  960  includes: an optical block  961 ; an imaging unit  962 ; a camera signal processing unit  963 ; an image data processing unit  964 ; a display unit  965 ; an external interface unit  966 ; a memory unit  967 ; a media drive  968 ; an OSD unit  969 ; and a control unit  970 . In addition, a user interface unit  971  is connected to the control unit  970 . Furthermore, the image data processing unit  964 , the external interface unit  966 , the memory unit  967 , the media drive  968 , the OSD unit  969 , the control unit  970 , and the like are interconnected through a bus  972 . 
     The optical block  961  is configured by using a focusing lens, a diaphragm mechanism, and the like. The optical block  961  forms the optical image of a subject on the imaging surface of the imaging unit  962 . The imaging unit  962  is configured by using a CCD or CMOS image sensor and generates an electrical signal according to the optical image through a photoelectric conversion and supplies the generated electrical signal to the camera signal processing unit  963 . 
     The camera signal processing unit  963  performs various kinds of camera signal processing such as a knee correction, a gamma correction, and a color correction for the electrical signal supplied from the imaging unit  962 . The camera signal processing unit  963  supplies image data after the camera signal processing to the image data processing unit  964 . 
     The image data processing unit  964  performs a coding process of the image data supplied from the camera signal processing unit  963 . The image data processing unit  964  supplies coded data that is generated by performing the coding process to the external interface unit  966  or the media drive  968 . In addition, the image data processing unit  964  performs a decoding process of the coded data supplied from the external interface unit  966  or the media drive  968 . The image data processing unit  964  supplies the image data generated by performing the decoding process to the display unit  965 . In addition, the image data processing unit  964  performs the process of supplying the image data supplied from the camera signal processing unit  963  to the display unit  965  and supplies display data acquired from the OSD unit  969  to the display unit  965  with being overlapped with the image data. 
     The OSD unit  969  generates display data such as a menu screen or an icon that is configured by symbols, characters, or graphics and outputs the generated display data to the image data processing unit  964 . 
     The external interface unit  966 , for example, is configured by a USB input/output terminal and the like and is connected to the printer in a case where an image is printed. In addition, to the external interface unit  966 , a drive is connected as is necessary, a removable medium such as a magnetic disk or an optical disc is appropriately installed, and a computer program read therefrom is installed as is necessary. Furthermore, the external interface unit  966  includes a network interface that is connected to a predetermined network such as a LAN or the Internet. For example, in accordance with an instruction from the user interface unit  971 , the control unit  970  can read coded data from the media drive  968  and supply the read coded data from the external interface unit  966  to another device connected through a network. In addition, the control unit  970  can acquire coded data or image data, which is supplied from another device through a network, through the external interface unit  966  and supply the acquired data to the image data processing unit  964 . 
     As the recording media driven by the media drive  968 , for example, an arbitrary readable/writable removable medium such as a magnetic disk, a magneto-optical disk, an optical disc, or a semiconductor memory is used. In addition, the type of the recoding medium as a removable medium is an arbitrary and thus, may be a tape device, a disk, or a memory card. Furthermore, a non-contact IC (Integrated Circuit) card or the like may be used as the recording medium. 
     In addition, by integrating the media drive  968  and the recording medium together, for example, the recording medium may be configured by a non-portable recording medium such as a built-in type hard disk drive or an SSD (Solid State Drive). 
     The control unit  970  is configured by using a CPU. The memory unit  967  stores programs that are executed by the control unit  970 , various kinds of data that is necessary for the process performed by the control unit  970 , and the like. A program stored in the memory unit  967  is read and executed by the control unit  970  at predetermined timing such as the start-up of the imaging device  960 . The control unit  970  executes programs, thereby performing control of each unit such that the imaging device  960  operates in accordance with a user operation. 
     In the imaging device configured in this way, the functions of the encoding device and the decoding device (a coding method and a decoding method) according to the present application is implemented in the image data processing unit  964 . Accordingly, the amount of information relating to the information specifying a reference image can be reduced. In addition, a coded stream in which the amount of information relating to the information specifying a reference image is reduced can be decoded. 
     &lt;Example of Application of Hierarchical Coding&gt; 
     (First System) 
     Next, a specific example of the use of scalable coded data that is hierarchically coded (coded in a scalable manner) will be described. The scalable coding, for example, as in an example illustrated in  FIG. 67 , is used for selecting data to be transmitted. 
     In a data transmission system  1000  illustrated in  FIG. 67 , a delivery server  1002  reads scalable coded data stored in a scalable coded data storage unit  1001  and delivers the read scalable coded data to a terminal device such as a personal computer  1004 , an AV device  1005 , a tablet device  1006 , or a mobile phone  1007  through a network  1003 . 
     At that time, the delivery server  1002  selects and transmits coded data having a suitable quality in accordance with the capability of the terminal device, communication environments, and the like. Even when the delivery server  1002  transmits data having unnecessary high quality, a high quality image cannot be acquired in the terminal device, and there is concern that it may cause the occurrence of a delay or an overflow. In addition, there is concern that a communication band is unnecessarily occupied, or the load of the terminal device unnecessarily increases. In contrast, when the delivery server  1002  transmits data having unnecessarily low quality, there is concern that an image having sufficient image quality cannot be acquired in the terminal device. Accordingly, the delivery server  1002  appropriately reads and transmits scalable coded data stored in the scalable coded data storage unit  1001  as coded data having quality that is appropriate to the capability of the terminal device, the communication environments, and the like. 
     For example, the scalable coded data storage unit  1001  is assumed to store scalable coded data (BL+EL)  1011  that is coded in a scalable manner. This scalable coded data (BL+EL)  1011  is coded data including both a base layer and an enhancement layer and is data from which an image of the base layer and an image of the enhancement layer can be acquired by decoding the scalable coded data. 
     The delivery server  1002  selects an appropriate layer in accordance with the capability of a terminal transmitting data, the communication environments, and the like and reads data of the layer. For example, for a personal computer  1004  or a tablet device  1006  that has high processing capability, the delivery server  1002  reads the scalable coded data (BL+EL)  1011  having high quality from the scalable coded data storage unit  1001  and transmits the scalable coded data as it is. In contrast, for example, for an AV device  1005  or a mobile phone  1007  having a low processing capability, the delivery server  1002  extracts the data of the base layer from the scalable coded data (BL+EL)  1011  and transmits scalable coded data (BL)  1012  that has the same content as the scalable coded data (BL+EL)  1011  and has quality lower than the scalable coded data (BL+EL)  1011 . 
     As above, by using the scalable coded data, the amount of data can be easily adjusted. Accordingly, the occurrence of a delay or an overflow can be suppressed, and an unnecessary increase in the load of the terminal device or the communication medium can be suppressed. In addition, in the scalable coded data (BL+EL)  1011 , since the redundancy between layers is reduced, the amount of data can be reduced to be less than that of a case where the coded data of each layer is configured as individual data. Accordingly, the storage area of the scalable coded data storage unit  1001  can be used more efficiently. 
     In addition, like the personal computer  1004  and the mobile phone  1007 , various devices can be applied as the terminal devices, and accordingly, the capabilities of the hardware of the terminal devices differ depending on the devices. Furthermore, since there are various applications that are executed by the terminal devices, there are various capabilities of the software. In addition, as the network  1003  that serves as the communication medium, any of all the communication networks including a wired network, a wireless network, or both the wired and wireless networks such as the Internet or the LAN (Local Area Network) can be applied, and accordingly, the data transmission capability varies. Furthermore, there is concern that the data transmission capability may change in accordance with the other communications or the like. 
     Thus, the delivery server  1002 , before the start of data transmission, may communicate with a terminal device that is the transmission destination of the data so as to acquire information relating to the capability of the terminal device such as the hardware capability of the terminal device and the capability of the application (software) executed by the terminal device, and information relating to the communication environments such as the usable bandwidth of the network  1003  and the like. In addition, the delivery server  1002  may be configured to select an appropriate layer based on the information acquired here. 
     In addition, the extraction of a layer may be performed by the terminal device. For example, the personal computer  1004  may decode the transmitted scalable coded data (BL+EL)  1011  and display an image of the base layer or an image of the enhancement layer. Furthermore, for example, the personal computer  1004  may extract the scalable coded data (BL)  1012  of the base layer from the transmitted scalable coded data (BL+EL)  1011  and may store the extracted scalable coded data, transmit the extracted scalable coded data to another device, or decode the extracted scalable coded data and display the image of the base layer. 
     Here, it is apparent that all the scalable coded data storage unit  1001 , the delivery server  1002 , the network  1003 , and the number of the terminal devices are arbitrary. In the description presented above, while the example has been described in which the delivery server  1002  transmits data to the terminal device, the example of the use is not limited thereto. The data transmission system  1000  may be applied to an arbitrary system as long as the system selects an appropriate layer in accordance with the capability of the terminal device, the communication environments, and the like and transmits the selected layer when the coded data coded in a scalable manner is transmitted to the terminal device. 
     (Second System) 
     In addition, the scalable coding, for example, as in an example illustrated in  FIG. 68 , is used for transmission through a plurality of communication media. 
     In a data transmission system  1100  illustrated in  FIG. 68 , a broadcasting station  1101  transmits scalable coded data (BL)  1121  of the base layer through terrestrial broadcasting  1111 . In addition, the broadcasting station  1101  transmits scalable coded data (EL)  1122  of the enhancement layer through an arbitrary network  1112  that is configured by a wired communication network, a wireless communication network, or both the wired and wireless communication networks (for example, the data is packetized and transmitted). 
     A terminal device  1102  has a function for receiving the terrestrial broadcasting  1111  that is broadcasted by the broadcasting station  1101  and receives the scalable coded data (BL)  1121  of the base layer that is transmitted through the terrestrial broadcasting  1111 . In addition, the terminal device  1102  further has a communication function for performing communication through a network  1112  and receives the scalable coded data (EL)  1122  of the enhancement layer that is transmitted through the network  1112 . 
     The terminal device  1102 , for example, in accordance with a user&#39;s instruction or the like, acquires an image of the base layer by decoding the scalable coded data (BL)  1121  of the base layer that is acquired through the terrestrial broadcasting  1111 , stores the acquired scalable coded data, or transmits the acquired scalable coded data to another device. 
     In addition, the terminal device  1102 , for example, in accordance with a user&#39;s instruction, composes the scalable coded data (BL)  1121  of the base layer that is acquired through the terrestrial broadcasting  1111  and the scalable coded data (EL)  1122  of the enhancement layer that is acquired through the network  1112  so as to acquire the scalable coded data (BL+EL), decodes the scalable coded data so as to acquire an image of the enhancement layer, or transmits the scalable coded data to another device. 
     As above, the scalable coded data, for example, can be transmitted through a communication medium that is different for each layer. Accordingly, the load can be distributed, and the occurrence of a delay or an overflow can be suppressed. 
     In addition, depending on the situation, the communication medium that is used for the transmission may be configured to be selected for each layer. For example, it may be configured such that the scalable coded data (BL)  1121  of the base layer of which the data amount is relatively large is transmitted through a communication medium having a wide bandwidth, and the scalable coded data (EL)  1122  of the enhancement layer of which the data amount is relatively small is transmitted through a communication medium having a narrow bandwidth. In addition, for example, the communication medium through which the scalable coded data (EL)  1122  of the enhancement layer is transmitted may be configured to be switched between the network  1112  and the terrestrial broadcasting  1111  in accordance with the usable bandwidth of the network  1112 . This similarly applies to the data of an arbitrary layer. 
     By controlling as such, an increase in the load for the data transmission can be further suppressed. 
     Here, the number of layers is arbitrary, and the number of communication media used for the transmission is also arbitrary. In addition, the number of the terminal devices  1102  that are the delivery destination of data is arbitrary as well. Furthermore, in the description presented above, while the example has been described in which broadcasting is performed from the broadcasting station  1101 , the example of the use is not limited thereto. The data transmission system  1100  may be applied to an arbitrary system as long as the system divides coded data, which is coded in a scalable manner, into a plurality of parts in units of layers and transmits divided data through a plurality of lines. 
     (Third System) 
     In addition, the scalable coded data, for example, as in an example illustrated in  FIG. 69 , is used for storing coded data. 
     In an imaging system  1200  illustrated in  FIG. 69 , an imaging device  1201  performs scalable coding of image data that is acquired by imaging a subject  1211  and supplies resultant image data to a scalable coded data storage device  1202  as scalable coded data (BL+EL)  1221 . 
     The scalable coded data storage device  1202  stores the scalable coded data (BL+EL)  1221  supplied from the imaging device  1201  with quality according to the situation. For example, in the case of a normal time, the scalable coded data storage device  1202  extracts data of the base layer from the scalable coded data (BL+EL)  1221  and stores the extracted data as the scalable coded data (BL)  1222  of the base layer that has low quality and a small data amount. In contrast, for example, in the case of an attention time, the scalable coded data storage device  1202  stores the scalable coded data (BL+EL)  1221  that has high quality and a large amount of data as it is. 
     In this way, the scalable coded data storage device  1202  can store an image with high image quality only in a necessary case. Accordingly, while a decrease in the value of the image due to deterioration of the image quality is suppressed, an increase in the amount of data can be suppressed, whereby the use efficiency of the storage area can be improved. 
     For example, it is assumed that the imaging device  1201  is a monitoring camera. In a case where a monitoring target (for example, an intruder) is not shown up in a captured image (in the case of the normal time), the possibility that the content of the captured image is of no importance is high, and a decrease in the amount of data has the priority, and the image data (scalable coded data) is stored with low quality. In contrast, in a case where a monitoring target is shown up in a captured image as a subject  1211  (in the case of the attention time), the possibility that the content of the captured image is of importance is high, and the image quality has the priority, and the image data (scalable coded data) is stored with high quality. 
     Here, whether it is the normal time or the attention time, for example, may be determined by analyzing the image using the scalable coded data storage device  1202 . In addition, it may be configured such that the determination process is performed by the imaging device  1201 , and a result of the determination is transmitted to the scalable coded data storage device  1202 . 
     Here, the determination criterion for determining the normal time or the attention time is arbitrary, and the content of the image that is the determination criterion is arbitrary. In addition, a condition other than the content of the image may be set as the determination criterion. For example, the determination may be changed in accordance with the size, the waveform, or the like of recorded speech, may be changed for every predetermined time, or may be changed in accordance with an instruction, which is supplied from the outside, such as a user&#39;s instruction. 
     In addition, in the description presented above, while the example has been described in which switching between two states of the normal time and the attention time is performed, the number of the states is arbitrary. Thus, for example, it may be configured such that switching is performed among three or more states including a normal time, a weak attention time, an attention time, and a strong attention time. However, the upper limit of the number of states among which the switching is performed depends on the number of layers of the scalable coded data. 
     Furthermore, the imaging device  1201  may be configured to determine the number of layers of the scalable coding in accordance with the states. For example, in the case of the normal time, the imaging device  1201  may be configured to generate scalable coded data (BL)  1222  of the base layer that has low quality and a small amount of data and supply the generated scalable coded data to the scalable coded data storage device  1202 . In addition, for example, in the case of the attention time, the imaging device  1201  may be configured to generate scalable coded data (BL+EL)  1221  of the base layer that has high quality and a large amount of data and supply the generated scalable coded data to the scalable coded data storage device  1202 . 
     In the description presented above, while the monitoring camera has been described as an example, the use of this imaging system  1200  is arbitrary but is not limited to the monitoring camera. 
     Here, the LCU is a CU (Coding Unit) having a maximal size, and the CTU (Coding Tree Unit) is a unit that includes a CTB (Coding Tree Block) of the LCU and parameters at the time of performing the process at the LCU base (level). In addition, the CU configuring the CTU is a unit that includes a CB (Coding Block) and parameters at the time of performing the process at the CU base (level). 
     Other Examples 
     While the examples of the devices, the systems, and the like to which the present technology is applied have been described above, the present technology is not limited thereto. Thus, the present technology may be applied as all the configurations mounted to such a device or devices configuring such a system, for example, a processor as a system LSI (Large Scale Integration) or the like, a module that uses a plurality of processors or the like, a unit that uses a plurality of modules or the like, or a set or the like (in other words, a part of the configuration of the device) acquired by adding other functions to the unit. 
     (Configuration Example of Video Set) 
     An example of a case where the present technology is applied as a set will be described with reference to  FIG. 70 .  FIG. 70  illustrates an example of the schematic configuration of a video set to which the present technology is applied. 
     Recently, the implementation of multiple functions of an electronic device is in progress, and, in the development or the manufacturing thereof, in a case where a part of the configuration is provided for sale, provision, or the like, there are not only a case where the configuration having one function is applied but also a case where one set having a plurality of functions, which is acquired by combining a plurality of configurations having relating function, is applied, which is widely used. 
     The video set  1300  illustrated in  FIG. 70  has such a multi-function configuration and is acquired by combining a device having a function relating to image coding or image decoding (any one thereof or both thereof) with devices having other functions relating to the function. 
     As illustrated in  FIG. 70 , the video set  1300  includes a module group that includes a video module  1311 , an external memory  1312 , a power management module  1313 , a front end module  1314 , and the like and devices having related functions of a connectivity  1321 , a camera  1322 , a sensor  1323 , and the like. 
     A module is formed as a component having a function having unity by arranging several component functions relating to each other together. While a specific physical configuration is arbitrary, for example, a module acquired by arranging a plurality of processors each having a function, an electronic circuit component such as a resistor or a capacitor, and other devices or the like on a wiring board or the like so as to be integrated together may be considered. In addition, it may be considered to form a new module by combining a module with other modules, processors, and the like. 
     In the example illustrated in  FIG. 70 , the video module  1311  is acquired by combining configurations having functions relating to image processing and includes: an application processor; a video processor; a broadband modem  1333 ; and an RF module  1334 . 
     The processor is acquired by integrating a configuration having a predetermined function on a semiconductor chip as SoC (System On a Chip) and, for example, there is also the processor that is called a system LSI (Large Scale Integration) or the like. The configuration having the predetermined function may be a logic circuit (hardware configuration), a configuration including a CPU, a ROM, a RAM, and the like and a program (software configuration) executed using them, or a configuration combining both the configurations described above. For example, it may be configured such that the processor includes logic circuits, a CPU, a ROM, a RAM, and the like, some functions are realized by the logic circuits (hardware configuration), and the other functions are realized by a program (software configuration) executed by the CPU. 
     The application processor  1331  illustrated in  FIG. 70  is a processor that executes an application relating to image processing. In order to realize predetermined functions, the application executed by the application processor  1331  may not only perform a calculation process but also control the configurations of the inside and the outside of the video module  1311  such as the video processor  1332  as is necessary. 
     The video processor  1332  is a processor that has a function relating to image coding and image decoding (one thereof or both thereof). 
     The broadband modem  1333  is a processor (or a module) relating to wired or wireless (or wired and wireless) broadband communication performed through a broadband line such as the Internet or a public telephone network. For example, the broadband modem  1333  converts data (digital signal) to be transmitted into an analog signal through digital modulation or the like or demodulates a received analog signal so as to be converted into data (digital signal). For example, the broadband modem  1333  can perform digital modulation/demodulation of arbitrary information such as image data processed by the video processor  1332 , a stream in which the image data is coded, an application program, and setting data. 
     The RF module  1334  is a module that performs frequency conversion, modulation/demodulation, amplification, a filter process, and the like for an RF (Radio Frequency) signal that is transmitted/received through an antenna. For example, the RF module  1334  generates an RF signal by performing frequency conversion and the like for a dedicated line connection system signal generated by the broadband modem  1333 . In addition, for example, the RF module  1334  generates a dedicated line connection system signal by performing frequency conversion and the like for an RF signal received through the front end module  1314 . 
     In addition, as denoted by a dotted line  1341  in  FIG. 70 , the application processor  1331  and the video processor  1332  may be integrated so as to be configured as one processor. 
     The external memory  1312  is a module that is disposed outside the video module  1311  and includes a storage device used by the video module  1311 . The storage device of the external memory  1312  may be realized by a certain physical configuration. However, generally, since the storage device is frequently used for storing data having a large capacity such as image data configured in units of frames, the storage device is preferably realized by a semiconductor memory that has a large capacity at relatively low cost such as a DRAM (Dynamic Random Access Memory). 
     The power management module  1313  manages and controls the supply of power to the video module  1311  (each configuration within the video module  1311 ). 
     The front end module  1314  is a module that provides a front end function (a transmission/reception-end circuit on the antenna side) for the RF module  1334 . As illustrated in  FIG. 70 , the front end module  1314 , for example, includes an antenna unit  1351 , a filter  1352 , and an amplification unit  1353 . 
     The antenna unit  1351  includes an antenna that transmits/receives a wireless signal and a peripheral configuration thereof. The antenna unit  1351  transmits a signal supplied from the amplification unit  1353  as a wireless signal and supplies a received wireless signal to the filter  1352  as an electric signal (RF signal). The filter  1352  performs a filter process and the like for the RF signal received through the antenna unit  1351  and supplies the RF signal after the process to the RF module  1334 . The amplification unit  1353  amplifies the RF signal supplied from the RF module  1334  and supplies the amplified RF signal to the antenna unit  1351 . 
     The connectivity  1321  is a module that has a function relating to a connection to the outside. The physical configuration of the connectivity  1321  is arbitrary. For example, the connectivity  1321  includes a configuration having a communication function other than the communication specification to which the broadband modem  1333  corresponds, external input/output terminals, and the like. 
     For example, the connectivity  1321  may be configured to include a module having communication functions that are compliant with radio communication specifications such as Bluetooth (registered trademark), IEEE 802.11 (for example, Wi-Fi (Wireless Fidelity; registered trademark)), NFC (Near Field Communication), and IrDA (InfraRed Data Association) and an antenna that transmits/receives signals that are compliant with the specifications. In addition, for example, the connectivity  1321  may be configured to include a module having communication functions that are compliant with wired communication specifications such as USB (Universal Serial Bus) and HDMI (registered trademark) (High-Definition Multimedia Interface) and terminals that are compliant with the specifications. Furthermore, for example, the connectivity  1321  may be configured to have an additional data (signal) transmission function and the like of analog input/output terminals or the like. 
     In addition, the connectivity  1321  may be configured to include a device that is the transmission destination of data (signal). For example, the connectivity  1321  may be configured to include a drive (including not only a drive of a removable medium but also a hard disk, an SSD (Solid State Drive), a NAS (Network Attached Storage), and the like) that performs data reading or data writing for a recoding medium such as a magnetic disk, an optical disc, a magneto-optical disk, or a semiconductor memory. Furthermore, the connectivity  1321  may be configured to include an output device (a monitor, a speaker, or the like) of an image or an audio. 
     The camera  1322  is a module that has a function for acquiring image data of a subject by imaging the subject. The image data acquired by an imaging process performed by the camera  1322 , for example, is supplied to the video processor  1332  and is coded. 
     The sensor  1323  is a module that has the function of an arbitrary sensor such as an audio sensor, an ultrasonic sensor, an optical sensor, an illuminance sensor, an infrared sensor, an image sensor, a rotation sensor, an angle sensor, an angular velocity sensor, a speed sensor, an acceleration sensor, a tilt sensor, a magnetic identification sensor, an impact sensor, or a temperature sensor. Data that is detected by the sensor  1323 , for example is supplied to the application processor  1331  and is used by the application and the like. 
     In the description presented above, each configuration described as a module may be realized by a processor, and each configuration described as a processor may be realized by a module. 
     As will be described later, the present technology may be applied to the video processor  1332  of the video set  1300  having the configuration as described above. Accordingly, the video set  1300  may be configured as the set to which the present technology is applied. 
     (Configuration Example of Video Processor) 
       FIG. 71  illustrates an example of the schematic configuration of the video processor  1332  ( FIG. 70 ) to which the present technology is applied. 
     In the example illustrated in  FIG. 71 , the video processor  1332  has a function for receiving an input of a video signal and an audio signal and coding the received signals in accordance with a predetermined system and a function for decoding coded video data and coded audio data and reproducing and outputting a video signal and an audio signal. 
     As illustrated in  FIG. 71 , the video processor  1332  includes: a video input processing unit  1401 ; a first image enlargement/reduction unit  1402 ; a second image enlargement/reduction unit  1403 ; a video output processing unit  1404 ; a frame memory  1405 ; and a memory control unit  1406 . In addition, the video processor  1332  includes: an encoding/decoding engine  1407 ; video ES (Elementary Stream) buffers  1408 A and  1408 B, and audio ES buffers  1409 A and  1409 B. In addition, the video processor  1332  includes: an audio encoder  1410 ; an audio decoder  1411 ; a multiplexer (MUX)  1412 ; a demultiplexer (DMUX)  1413 ; and a stream buffer  1414 . 
     The video input processing unit  1401 , for example, acquires a video signal input from the connectivity  1321  ( FIG. 70 ) or the like and converts the acquired video signal into digital image data. The first image enlargement/reduction unit  1402  performs format conversion and an image enlargement/reduction process for the image data. The second image enlargement/reduction unit  1403 , for the image data, performs an image enlargement/reduction process in accordance with a format of the output destination through the video output processing unit  1404  or performs format conversion and an image enlargement/reduction process, which are similar to those of the first image enlargement/reduction unit  1402 , and the like. The video output processing unit  1404  performs format conversion, conversion into an analog signal, and the like for the image data and outputs a resultant signal, for example, to the connectivity  1321  ( FIG. 70 ) or the like as a reproduced video signal. 
     The frame memory  1405  is a memory for image data that is shared by the video input processing unit  1401 , the first image enlargement/reduction unit  1402 , the second image enlargement/reduction unit  1403 , the video output processing unit  1404 , and the encoding/decoding engine  1407 . The frame memory  1405  is realized as a semiconductor memory such as a DRAM. 
     The memory control unit  1406  receives a synchronization signal supplied from the encoding/decoding engine  1407  and controls an access to the frame memory  1405  for writing/reading in accordance with an access schedule for the frame memory  1405  that is written into an access management table  1406 A. The access management table  1406 A is updated by the memory control unit  1406  in accordance with the process that is performed by the encoding/decoding engine  1907 , the first image enlargement/reduction unit  1402 , the second image enlargement/reduction unit  1403 , and the like. 
     The encoding/decoding engine  1407  performs an encoding process of image data and performs a decoding process of a video stream that is acquired by coding the image data. For example, the encoding/decoding engine  1407  codes the image data read from the frame memory  1405  and sequentially writes the read image data into the video ES buffer  1408 A as a video stream. In addition, for example, the encoding/decoding engine  1407  sequentially reads the video stream from the video ES buffer  1408 B, decodes the read video stream, and sequentially writes the decoded video stream into the frame memory  1405  as image data. The encoding/decoding engine  1407  uses the frame memory  1405  as a work area in such coding or decoding processes. In addition, the encoding/decoding engine  1407 , for example, at the timing of starting the process of each macroblock, outputs a synchronization signal to the memory control unit  1406 . 
     The video ES buffer  1408 A buffers the video stream generated by the encoding/decoding engine  1407  and supplies the video stream to the multiplexer (MUX)  1412 . The video ES buffer  1408 B buffers the video stream supplied from the demultiplexer (DMUX)  1413  and supplies the video stream to the encoding/decoding engine  1407 . 
     The audio ES buffer  1409 A buffers the audio stream generated by the audio encoder  1410  and supplies the audio stream to the multiplexer (MUX)  1412 . The audio ES buffer  1409 B buffers the audio stream supplied from the demultiplexer (DMUX)  1413  and supplies the audio stream to the audio decoder  1411 . 
     The audio encoder  1410  converts an audio signal, for example, input from the connectivity  1321  ( FIG. 70 ) or the like, for example, into a digital signal and codes the converted audio signal in accordance with a predetermined system such as an MPEG audio system or an AC3 (AudioCode number 3) system. The audio encoder  1410  sequentially writes audio streams that are data acquired by coding the audio signals into the audio ES buffer  1409 A. The audio decoder  1411  decodes the audio stream supplied from the audio ES buffer  1409 B, performs conversion of the decoded audio stream, for example, into an analog signal and the like, and supplies the converted signal, for example, to the connectivity  1321  ( FIG. 70 ) and the like as a reproduced audio signal. 
     The multiplexer (MUX)  1412  multiplexes the video stream and the audio stream. The multiplexing method (in other words, the format of a bitstream generated by the multiplexing) is arbitrary. In addition, at the time of multiplexing, the multiplexer (MUX)  1412  may add predetermined header information or the like to the bit stream. In other words, the multiplexer (MUX)  1412  can convert the format of the stream through the multiplexing process. For example, by multiplexing the video stream and the audio stream, the multiplexer (MUX)  1412  converts the video stream and the audio stream into a transport stream that is a bitstream having a format for transmission. In addition, for example, by multiplexing the video stream and the audio stream, the multiplexer (MUX)  1412  converts the video stream and the audio stream into data (file data) having a format for recording. 
     The demultiplexer (DMUX)  1413  demultiplexes the bit stream in which the video stream and the audio stream are multiplexed using a method corresponding to the multiplexing process performed by the multiplexer (MUX)  1412 . In other words, the demultiplexer (DMUX)  1413  extracts a video stream and an audio stream from the bitstream read from the stream buffer  1414  (the video stream and the audio stream are separated). In other words, the demultiplexer (DMUX)  1413  can convert (inverse conversion of the conversion performed by the multiplexer (MUX)  1412 ) the format of the stream through the demultiplexing process. For example, the demultiplexer (DMUX)  1413  acquires the transport stream, for example, supplied from the connectivity  1321  ( FIG. 70 ), the broadband modem  1333  ( FIG. 70 ), or the like through the stream buffer  1414  and demultiplexes the acquired transport stream, thereby converting the transport stream into a video stream and an audio stream. In addition, for example, the demultiplexer (DMUX)  1413  acquires file data read from various recording media, for example, by the connectivity  1321  ( FIG. 70 ) through the stream buffer  1414  and demultiplexes the acquired file data, thereby converting the file data into a video stream and an audio stream. 
     The stream buffer  1414  buffers the bitstream. For example, the stream buffer  1414  buffers the transport stream supplied from the multiplexer (MUX)  1412  and supplies the transport stream, for example, to the connectivity  1321  ( FIG. 70 ), the broadband modem  1333  ( FIG. 70 ), and the like at predetermined timing or based on a request transmitted from the outside. 
     In addition, for example, the stream buffer  1414  buffers the file data supplied from the multiplexer (MUX)  1412  and supplies the file data, for example, to the connectivity  1321  ( FIG. 70 ) and the like at a predetermined timing or based on a request transmitted from the outside. 
     Furthermore, the stream buffer  1414  buffers the transport stream acquired, for example, through the connectivity  1321  ( FIG. 70 ), the broadband modem  1333  ( FIG. 70 ), or the like and supplies the transport stream to the demultiplexer (DMUX)  1413  at predetermined timing or based on a request from the outside, and the like. 
     In addition, the stream buffer  1414  buffers the file data read from various recording media, for example, by the connectivity  1321  ( FIG. 70 ) or the like and supplies the file data to the demultiplexer (DMUX)  1413  at predetermined timing or based on a request from the outside or the like. 
     Next, an example of the operation of the video processor  1332  having such a configuration will be described. For example, a video signal input to the video processor  1332  from the connectivity  1321  ( FIG. 70 ) or the like is converted into digital image data according to a predetermined system such as the 4:2:2 Y/Cb/Cr system by the video input processing unit  1401  and is sequentially written into the frame memory  1405 . This digital image data is read by the first image enlargement/reduction unit  1402  or the second image enlargement/reduction unit  1403 , and a format conversion into a predetermined system such as the 4:2:0 Y/Cb/Cr system or the like and the enlargement/reduction process is performed for the digital image data, and the processed digital image data is written again into the frame memory  1405 . This image data is coded by the encoding/decoding engine  1407  and is written into the video ES buffer  1408 A as a video stream. 
     In addition, the audio signal input from the connectivity  1321  ( FIG. 70 ) or the like to the video processor  1332  is coded by the audio encoder  1410  and is written into the audio ES buffer  1409 A as an audio stream. 
     The video stream stored in the video ES buffer  1408 A and the audio stream stored in the audio ES buffer  1409 A are read by the multiplexer (MUX)  1412 , are multiplexed, and are converted into a transport stream, file data, or the like. The transport stream generated by the multiplexer (MUX)  1412  is buffered into the stream buffer  1414  and then is output to the external network, for example, through the connectivity  1321  ( FIG. 70 ), the broadband modem  1333  ( FIG. 70 ), or the like. In addition, the file data generated by the multiplexer (MUX)  1412  is buffered into the stream buffer  1414 , then is output, for example, to the connectivity  1321  ( FIG. 70 ) or the like, and is recorded in any one of various recording media. 
     In addition, the transport stream that is input from the external network to the video processor  1332 , for example, through the connectivity  1321  ( FIG. 70 ), the broadband modem  1333  ( FIG. 70 ), or the like is buffered into the stream buffer  1414  and then is demultiplexed by the demultiplexer (DMUX)  1413 . In addition, the file data that is read from any one of the various recording media, for example, by the connectivity  1321  ( FIG. 70 ) or the like and is input to the video processor  1332  is buffered into the stream buffer  1414  and then is demultiplexed by the demultiplexer (DMUX)  1413 . In other words, the transport stream or the file data input to the video processor  1332  is separated into a video stream and an audio stream by the demultiplexer (DMUX)  1413 . 
     The audio stream is supplied to the audio decoder  1411  through the audio ES buffer  1409 B and is decoded, and the audio signal is reproduced. In addition, the video stream is written into the video ES buffer  1408 B, then is sequentially read by the encoding/decoding engine  1407 , is decoded, and is written into the frame memory  1405 . The decoded image data is enlarged or reduced by the second image enlargement/reduction unit  1403  and is written into the frame memory  1405 . Then, the decoded image data is read by the video output processing unit  1404 , has the format converted into a predetermined system such as the 4:2:2 Y/Cb/Cr system, and is further converted into an analog signal, and the video signal is reproduced and output. 
     In a case where the present technology is applied to the video processor  1332  configured as such, the present technology according to each embodiment described above may be applied to the encoding/decoding engine  1407 . In other words, the encoding/decoding engine  1407  may be configured to have the function of the encoding device  10  or the decoding device  110 . In addition, for example, the encoding/decoding engine  1407  may be configured to have the functions of the encoding device  150  and the decoding device  170 , the encoding device  190  and the decoding device  210 , or the encoding device  230  and the decoding device  270 . Furthermore, for example, the encoding/decoding engine  1407  may be configured to have the functions of the multiple viewpoint image encoding device  600  and the multiple viewpoint image decoding device  610 . By configuring as such, the video processor  1332  can acquire the same advantages as the advantages described above with reference to  FIGS. 1 to 61 . 
     In addition, in the encoding/decoding engine  1407 , the present technology (in other words, the functions of the image encoding device and the image decoding device according to each embodiment described above) may be realized by hardware such as logic circuits, may be realized by software such as a built-in program, or may be realized by both the hardware and the software. 
     (Another Configuration Example of Video Processor) 
       FIG. 72  is a diagram that illustrates another example of the schematic configuration of the video processor  1332  ( FIG. 70 ) to which the present technology is applied. In the case of the example illustrated in  FIG. 72 , the video processor  1332  has a function for coding/decoding the video data in accordance with a predetermined system. 
     More specifically, as illustrated in  FIG. 72 , the video processor  1332  includes: a control unit  1511 ; a display interface  1512 ; a display engine  1513 ; an image processing engine  1514 ; and an internal memory  1515 . In addition, the video processor  1332  includes: a codec engine  1516 ; a memory interface  1517 ; a multiplexer/demultiplexer (MUX DMUX)  1518 ; a network interface  1519 ; and a video interface  1520 . 
     The control unit  1511  controls the operations of processing units arranged within the video processor  1332  such as the display interface  1512 , the display engine  1513 , the image processing engine  1514 , and the codec engine  1516 . 
     As illustrated in  FIG. 72 , the control unit  1511 , for example, includes a main CPU  1531 , a sub CPU  1532 , and a system controller  1533 . The main CPU  1531  executes a program that is used for controlling the operation of each processing unit disposed within the video processor  1332 . The main CPU  1531  generates a control signal in accordance with the program or the like and supplies the control signal to each processing unit (in other words, controls the operation of each processing unit). The sub CPU  1532  achieves an auxiliary role for the main CPU  1531 . For example, the sub CPU  1532  executes a child process, a sub routine, and the like of the program executed by the main CPU  1531 . The system controller  1533  controls the operations of the main CPU  1531  and the sub CPU  1532  such as designation of programs to be executed by the main CPU  1531  and the sub CPU  1532 . 
     The display interface  1512  outputs the image data, for example, to the connectivity  1321  ( FIG. 70 ) or the like under the control of the control unit  1511 . For example, the display interface  1512  converts the image data that is digital data into an analog signal and outputs the image data to the monitoring device or the like of the connectivity  1321  ( FIG. 70 ) as a reproduced video signal or the image data that is the digital data. 
     The display engine  1513 , under the control of the control unit  1511 , performs various conversion processes such as a format conversion, a size conversion, and a color gamut conversion for the image data so as to be adjusted to the hardware specifications of the monitoring device displaying the image or the like. 
     The image processing engine  1514 , under the control of the control unit  1511 , performs predetermined image processing such as a filter process for improving the image quality or the like for the image data. 
     The internal memory  1515  is a memory disposed inside the video processor  1332  that is shared by the display engine  1513 , the image processing engine  1514 , and the codec engine  1516 . The internal memory  1515 , for example, is used for data interchange performed among the display engine  1513 , the image processing engine  1514 , and the codec engine  1516 . For example, the internal memory  1515  stores data supplied from the display engine  1513 , the image processing engine  1514 , or the codec engine  1516  and supplies the data to the display engine  1513 , the image processing engine  1514 , or the codec engine  1516  as is necessary (for example, in accordance with a request). While this internal memory  1515  may be realized by any storage device, generally, the internal memory  1515  is frequently used for storing data having a small capacity such as image data configured in units of blocks or parameters, and accordingly, it is preferably realized by a semiconductor memory having a relatively small capacity (for example, compared to the external memory  1312 ) and a high response speed such as a SRAM (Static Random Access Memory). 
     The codec engine  1516  performs the process relating to coding or decoding image data. The coding/decoding system to which the codec engine  1516  corresponds is arbitrary, and the number thereof may be one or two or more. For example, the codec engine  1516  may include a codec function of a plurality of coding/decoding systems and perform the coding of image data or the decoding of coded image data by using selected one of the plurality of coding/decoding systems. 
     In the example illustrated in  FIG. 72 , the codec engine  1516 , for example, includes MPEG-2 Video  1541 , AVC/H.264  1542 , HEVC/H.265  1543 , HEVC/H.265 (Scalable)  1544 , HEVC/H.265 (Multi-view)  1545 , and MPEG-DASH  1551  as functional blocks of the process relating to the codec. 
     The MPEG-2 Video  1541  is a functional block used for coding or decoding image data in accordance with the MPEG-2 system. The AVC/H.264  1542  is a functional block used for coding or decoding image data in accordance with the AVC system. In addition, the HEVC/H.265  1543  is a functional block used for coding or decoding image data in accordance with the HEVC system. The HEVC/H.265 (Scalable)  1544  is a functional block used for scalable coding or scalable decoding image data in accordance with the HEVC system. The HEVC/H.265 (Multi-view)  1545  is a functional block used for multiple viewpoint coding or multiple viewpoint decoding image data in accordance with the HEVC system. 
     The MPEG-DASH  1551  is a functional block used for transmitting/receiving image data in accordance with an MPEG-DASH (MPEG-Dynamic Adaptive Streaming over HTTP) system. The MPEG-DASH is a technology for streaming a video by using an HTTP (HyperText Transfer Protocol) and has a feature that one is selected from among a plurality of pieces of coded data having mutually-different resolutions and the like, which are prepared in advance, in units of segments and is transmitted. The MPEG-DASH  1551  performs generation of a stream, transmission control of the stream, and the like that are compliant with the specification, and, for coding/decoding image data, uses MPEG-2 Video  1541  or HEVC/H.265 (Multi-view)  1545  described above. 
     The memory interface  1517  is an interface used for the external memory  1312 . Data supplied from the image processing engine  1514  or the codec engine  1516  is supplied to the external memory  1312  through the memory interface  1517 . In addition, the data read from the external memory  1312  is supplied to the video processor  1332  (the image processing engine  1514  or the codec engine  1516 ) through the memory interface  1517 . 
     The multiplexer/demultiplexer (MUX DMUX)  1518  multiplexes or demultiplexes various kinds of data relating to an image such as a bitstream of coded data, image data, or a video signal. The multiplexing/demultiplexing method is arbitrary. For example, at the time of the multiplexing process, the multiplexer/demultiplexer (MUX DMUX)  1518  may not only arrange a plurality of pieces of data into one but also add predetermined header information or the like to the data. In addition, at the time of the demultiplexing process, the multiplexer/demultiplexer (MUX DMUX)  1518  may not only divide one piece of data into a plurality of parts but add predetermined header information or the like to the divided data. In other words, the multiplexer/demultiplexer (MUX DMUX)  1518  can convert the format of data through a multiplexing/demultiplexing process. For example, the multiplexer/demultiplexer (MUX DMUX)  1518  can convert the bitstream into a transport stream that is in the format for transmission or data (file data) that is in the file format for recording by multiplexing the bitstream. It is apparent that the inverse conversion can be performed through a demultiplexing process. 
     The network interface  1519  is a dedicated interface such as the broadband modem  1333  ( FIG. 70 ) or the connectivity  1321  ( FIG. 70 ). The video interface  1520  is a dedicated interface such as the connectivity  1321  ( FIG. 70 ) or the camera  1322  ( FIG. 70 ). 
     Next, an example of the operation of such a video processor  1332  will be described. For example, when a transport stream is received from the external network, for example, through the connectivity  1321  ( FIG. 70 ), the broadband modem  1333  ( FIG. 70 ), or the like, the transport stream is supplied to the multiplexer/demultiplexer (MUX DMUX)  1518  through the network interface  1519 , is demultiplexed, and is decoded by the codec engine  1516 . For the image data acquired by the decoding process performed by the codec engine  1516 , for example, predetermined image processing is performed by the image processing engine  1514 , and predetermined conversion is performed by the display engine  1513 , the resultant image data is supplied, for example, to the connectivity  1321  ( FIG. 70 ) or the like through the display interface  1512 , and the image is displayed on the monitor. In addition, for example, the image data acquired by the decoding process performed by the codec engine  1516  is re-coded by the codec engine  1516 , is multiplexed by the multiplexer/demultiplexer (MUX DMUX)  1518 , is converted into file data, is output, for example, to the connectivity  1321  ( FIG. 70 ) or the like through the video interface  1520 , and is recorded on any one of the various recording media. 
     In addition, for example, coded data that is acquired by coding the image data read from a recording medium not illustrated in the figure by the connectivity  1321  ( FIG. 70 ) or the like is supplied to the multiplexer/demultiplexer (MUX DMUX)  1518  through the video interface  1520 , is demultiplexed, and is decoded by the codec engine  1516 . For the image data acquired by the decoding process performed by the codec engine  1516 , predetermined image processing is performed by the image processing engine  1514 , and a predetermined conversion is performed by the display engine  1513 , and the resultant image data is supplied, for example, to the connectivity  1321  ( FIG. 70 ) or the like through the display interface  1512 , and the image is displayed on the monitor. Furthermore, for example, the image data acquired by the decoding process performed by the codec engine  1516  is re-coded by the codec engine  1516 , is multiplexed by the multiplexer/demultiplexer (MUX DMUX)  1518 , is converted into a transport stream, is supplied, for example, to the connectivity  1321  ( FIG. 70 ), the broadband modem  1333  ( FIG. 70 ), or the like through the network interface  1519 , and is transmitted to another device not illustrated in the figure. 
     In addition, the interchange of image data or other data between processing units disposed within the video processor  1332 , for example, is performed using the internal memory  1515  or the external memory  1312 . In addition, the power management module  1313 , for example, controls the supply of power to the control unit  1511 . 
     In a case where the present technology is applied to the video processor  1332  configured as such, the present technology according to each embodiment described above may be applied to the codec engine  1516 . In other words, for example, the codec engine  1516  may include a functional block that realizes the encoding device  10  or the decoding device  110 . In addition, for example, the codec engine  1516  may be configured to include functional blocks that realize the encoding device  150  and the decoding device  170 , the encoding device  190  and the decoding device  210 , or the encoding device  230  and the decoding device  270 . Furthermore, for example, the codec engine  1516  may be configured to include the functions of the multiple viewpoint image encoding device  600  and the multiple viewpoint image decoding device  610 . By configuring as such, the video processor  1332  can acquire the same advantages as the advantages described above with reference to  FIGS. 1 to 61 . 
     In addition, in the codec engine  1516 , the present technology (in other words, the functions of the image encoding device and the image decoding device according to each embodiment described above) may be realized by hardware such as logic circuits, may be realized by software such as a built-in program, or may be realized by both the hardware and the software. 
     As above, while two configurations of the video processor  1332  have been described as examples, the configuration of the video processor  1332  is arbitrary and may be a configuration other than the two configurations described above. In addition, this video processor  1332  may be configured by either one semiconductor chip or a plurality of semiconductor chips. For example, the video processor  1332  may be configured by a three-dimensional laminated LSI in which a plurality of semiconductors are laminated. In addition, the video processor  1332  may be realized by a plurality of LSI&#39;s. 
     (Example of Application to Device) 
     The video set  1300  may be built in various devices that process image data. For example, the video set  1300  may be built in the television apparatus  900  ( FIG. 63 ), the mobile phone  920  ( FIG. 64 ), the recording and reproducing device  940  ( FIG. 65 ), the imaging device  960  ( FIG. 66 ), and the like. By building the video set  1300  therein, the devices can acquire advantages that are the same as the advantages described above with reference to  FIGS. 1 to 61 . 
     In addition, the video set  1300 , for example, may be built in the terminal devices of the data transmission system  1000  illustrated in  FIG. 67  such as the personal computer  1004 , the AV device  1005 , the tablet device  1006 , and the mobile phone  1007 , the broadcasting station  1101  and the terminal device  1102  of the data transmission system  1100  illustrated in  FIG. 68 , and the imaging device  1201  and the scalable coded data storage device  1202  of the imaging system  1200  illustrated in  FIG. 69 , and the like. By building the video set  1300  therein, the devices can acquire advantages that are the same as the advantages described above with reference to  FIGS. 1 to 61 . 
     Furthermore, some of the configurations of the video set  1300  described above may be configurations to which the present technology is applied in a case where the video processor  1332  is included therein. For example, only the video processor  1332  may be configured as a video processor to which the present technology is applied. In addition, as described above, the processor, the video module  1311 , and the like denoted by the dotted line  1341  may be configured as a processor, a module, and the like to which the present technology is applied. Furthermore, for example, the video module  1311 , the external memory  1312 , the power management module  1313 , and the front end module  1314  may be combined so as to be configured as a video unit  1361  to which the present technology is applied. In any of the configurations, the same advantages as those described above with reference to  FIGS. 1 to 61  can be acquired. 
     In other words, any configuration that includes the video processor  1332 , similar to the case of the video set  1300 , may be built in various devices that process image data. For example, the video processor  1332 , the processor and the video module  1311  denoted by the dotted line  1341 , or the video unit  1361  may be built in the television apparatus  900  ( FIG. 63 ), the mobile phone  920  ( FIG. 64 ), the recording and reproducing device  940  ( FIG. 65 ), the imaging device  960  ( FIG. 66 ), the terminal devices of the data transmission system  1000  illustrated in  FIG. 67  such as the personal computer  1004 , the AV device  1005 , the tablet device  1006  and the mobile phone  1007 , the broadcasting station  1101  and the terminal device  1102  of the data transmission system  1100  illustrated in  FIG. 68 , and the imaging device  1201  and the scalable coded data storage device  1202  of the imaging system  1200  illustrated in  FIG. 69 , and the like. By building any configuration to which the present technology is applied therein, similar to the case of the video set  1300 , the devices can acquire the same advantages as those described above with reference to  FIGS. 1 to 61 . 
     In the present specification, the examples have been described in which various kinds of information are multiplexed into a coded stream, and the coded stream is transmitted from the coding side to the decoding side. However, the technique for transmitting the information is not limited thereto. For example, the information may be transmitted or recorded as separate data associated with a coded bitstream without being multiplexed into the coded bit stream. Here, the term “being associated” represents that an image (a slice, a block, or the like; it may be a part of the image) included in a bitstream and information corresponding to the image are linked to each other at the time of the decoding process. In other words, the information may be transmitted on a transmission line that is different from that of the image (or the bitstream). Furthermore, the information may be recorded on a recording medium (or a different storage area of the same recoding medium) different from the recoding medium of the image (or the bitstream). In addition, the information and the image (or the bitstream) may be associated with each other in an arbitrary unit such as a plurality of frames, one frame, or a part of the frame. 
     The present technology may be applied to devices used when image information (bitstream) compressed through an orthogonal transform such as a discrete cosine transform and motion compensation is transmitted and received through a network medium such as satellite broadcasting, a cable TV, the internet, or the mobile phone or when the compressed image information is processed on a storage medium such as an optical disc, a magnetic disk, or a flash memory as in MPEG, H.26x, or the like. 
     In addition, the present technology, for example, may be applied to HTTP streaming such as MPEG DASH in which, from among a plurality of pieces of coded data having mutually-different resolutions or the like, appropriate coded data is selected and used in units of segments. 
     Furthermore, the coding system according to the present technology may be a coding system other than the HEVC system. 
     Embodiments of the present technology are not limited to the embodiments described above, and various changes can be made in the range not departing from the concept of the present technology therein. 
     In addition, the present technology may have the following configurations. 
     (1) 
     An encoding device including: 
     a predicted image generation unit configured to generate a predicted image using a reference image; and 
     a transmission unit configured to transmit reference information representing whether reference image specifying information specifying the reference image of a prior image that is an image prior to a current coding image in coding order is used as the reference image specifying information of the current coding image in a case where the current coding image is an image other than a first image of a GOP (Group of Picture). 
     (2) 
     The encoding device according to (1), wherein the transmission unit, in a case where the reference information represents that the reference image specifying information of the prior image is used as the reference image specifying information of the current coding image, transmits prior image specifying information that specifies the prior image. 
     (3) 
     The encoding device according to (2), wherein the transmission unit, in a case where the reference information represents that the reference image specifying information of the prior image is not used as the reference image specifying information of the current coding image, transmits the reference image specifying information of the current coding image. 
     (4) 
     The encoding device according to (3), further including a reference image information setting unit configured to set a plurality of pieces of reference image information that includes the reference information and the prior image specifying information or the reference image specifying information, 
     wherein the transmission unit transmits the plurality of pieces of reference image information set by the reference image information setting unit and, in a case where the current coding image is an image other than the first image of the GOP (Group of Picture), transmits reference image information specifying information that specifies the reference image information of the current coding image among the plurality of pieces of reference image information. 
     (5) 
     The encoding device according to (4), 
     wherein the reference image information setting unit sets first reference image information including the reference image specifying information as the reference image information, and 
     the transmission unit, in a case where the current coding image is the first image of the GOP (Group of Picture), transmits the reference image information specifying information that specifies the first reference image information. 
     (6) 
     An encoding method, the encoding method including, by an encoding device: 
     a predicted image generating step of generating a predicted image using a reference image; and 
     a transmitting step of transmitting reference information representing whether reference image specifying information specifying the reference image of a prior image that is an image prior to a current coding image in coding order is used as the reference image specifying information of the current coding image in a case where the current coding image is an image other than a first image of a GOP (Group of Picture). 
     REFERENCE SIGNS LIST 
     
         
           10  Encoding device 
           12  Setting unit 
           13  Transmission unit 
           33  Calculation unit 
           47  Motion prediction/compensation unit 
           110  Decoding device 
           111  Reception unit 
           135  Addition unit 
           144  Reference image setting unit 
           145  Motion compensation unit 
           150  Encoding device 
           170  Decoding device 
           190  Encoding device 
           210  Decoding device 
           230  Encoding device 
           232  Setting unit 
           251  Motion prediction/compensation unit 
           270  Decoding device 
           292  Motion compensation unit