Patent Publication Number: US-2011069941-A1

Title: Recording apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a recoding apparatus, and, more particularly, to a recording apparatus having a function of changing a bit rate of an input stream to record the input stream changed in bit rate. 
     BACKGROUND ART 
     A high-definition recorder, etc., around in these years is known as a recorder capable of recording digital broadcasting, such as ground-wave digital broadcasting and BS digital broadcasting, directly on an HDD (Hard Disc Drive) and reproducing the digital broadcasting. Such digital broadcasting include a data-connected component (hereinafter “additional data”), such as subtitles and weather reports, in addition to audio/video, and the additional data is recorded simultaneously with audio/video so that the additional data can be reproduced and viewed upon reproduction of audio/video. 
     For example, patent Document 1 describes a technique for recording/reproducing not only such additional data but also data broadcasting, broadcasting other than data broadcasting, and streams having relevant data other than broadcasting data. According to this technique, a data broadcast, etc., is recorded by separating a broadcast-recording file from a broadcast-related file, and the recorded data broadcast is saved and edited in separation from main broadcasting. 
     Among such recorders, a certain type of recorder does not record broadcasting waves in their original form but records broadcasting waves after changing their bit rate while keeping their MPEG-2 format intact or after changing their audio/video format, thus being able to record a greater volume of contents. 
     A transcoding method is known as one of methods of bit rate change. The transcoding method enables recording at a compression ratio of 1/2 to 1/5, compared to the MPEG-2-based compression method, thus allowing recording of video data for a longer time of viewing while leaving the capacity of an HDD or optical disc as it is. Transcoding is a process of transforming video data, etc., compressed (coded) in a file format, into video data in another coding format or changing only the coding data rate (bit rate) of the video data, being used principally for moving picture transformation. Recently, household appliance manufactures have been putting new DVDs on the market, which DVDs have a function of real-time transcoding HDTV video data in the MPEG-2 format transmitted in ground-wave digital broadcasting into MPEG-4AVC/H264 (hereinafter “H264”) format data. 
     When bit rate change is carried out by this transcoding method, however, only the audio/video is subject to bit rate change, and data other than audio/video (additional data, etc.) usually does not survive. Specifically, additional data included in broadcasting waves, such as subtitles and various pieces of information, can be reproduced for use in a DR (Direct Recording) mode for recording the broadcasting waves directly onto an HDD, but is discarded when the broadcasting waves are encoded again in the H264 format and are recorded, in which case the additional data cannot be reproduced for use. This problem will be described referring to  FIGS. 5 and 6 . 
       FIGS. 4 and 5  are explanatory diagrams of a bit rate change process by a conventional recording apparatus. In  FIGS. 4 and 5 ,  101  denotes a tuner,  102  denotes a control portion, and  103  denotes a transcoder. In  FIGS. 4 and 5 , the recording apparatus is a recorder, of which a principal part configuration only is described. 
     In  FIG. 4 , the tuner  101  inputs an MPEG-2TS (Transport Stream) to the control portion  102  (S 101 ). The MPEG-2TS is composed mainly of video data, audio data, and additional data. The control unit  102  outputs the MPEG-2TS including the additional data to the transcoder  103  (S 102 ). The transcoder  103  then outputs an AVC (Advanced Video Coding) TS consisting only of video and audio to the control portion  102  (S 103 ). In this process, the transcoder  103  discards the additional data. 
     A configuration of  FIG. 5  is the same as the configuration of  FIG. 4  except a difference in that the control portion  102  discards additional data. The tuner  101  inputs an MPEG-2TS to the control portion  102  (S 111 ). The MPEG-2TS is composed mainly of video data, audio data, and additional data. The control unit  102  outputs the MPEG-2TS not including the additional data to the transcoder  103  (S 112 ). The transcoder  103  then outputs an AVCTS consisting only of video and audio to the control portion  102  (S 113 ). In this process, the control portion  102  discards the additional data. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-323325 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     According to the technique of the patent document 1, additional data can be saved and edited without being discarded. 
     When data streams are transcoded for recoding on a BD (Blu-ray Disc), DVD, etc., without discarding additional data, however, the data size of the additional data varies depending on channels and programs to make accurate bit rate estimation impossible, which leads to a problem that data streams cannot be recorded with consideration being given to a remaining capacity of the BD and of the DVD. This problem will be described in the following. 
     To reproduce the data-connected component (additional data) for use, recording a TS file including the additional data component is recommendable. Holding the additional data using a transcoder, for example, is a conceivable method. The TS file includes main components of video data, audio data, and additional data. The bit rate of the audio data among these data is 0.2 to 0.4 Mbps in the AAC format, which is extremely small. 
     A case is assumed where a plurality of contents recorded on an HDD in the DR mode are dubbed onto a BD. In the case of the conventional technique (i.e., case of discarding additional data), a bit rate is specified by the following method so that the contents are stored in a spare (remaining) capacity of the BD. 
     For example, when the spare capacity of the BD is 10 GBytes and the contents to be dubbed take 2 hours for dubbing, an expected total bit rate A (Mbps) is calculated by the following manner. 
     A×60×60×2=10×8×1024×1024×1024 
     It follows from this equation that 
     
       
         
           
             
               
                 
                   A 
                   = 
                     
                    
                   
                     
                       ( 
                       
                         10 
                         × 
                         8 
                         × 
                         1024 
                         × 
                         1024 
                         × 
                         1024 
                       
                       ) 
                     
                     / 
                     
                       ( 
                       
                         60 
                         × 
                         60 
                         × 
                         2 
                       
                       ) 
                     
                   
                 
               
             
             
               
                 
                   = 
                     
                    
                   11930464.7 
                 
               
             
             
               
                 
                   = 
                     
                    
                   
                     11.9 
                      
                     
                         
                     
                      
                     
                       ( 
                       Mbps 
                       ) 
                     
                   
                 
               
             
           
         
       
     
     Determining the total bit rate A to be 11.9 Mbps, therefore, allows storing the contents with the recoding time of 2 hours in the spare capacity (10 GBytes) of the BD. In this case, if the bit rate of audio data is determined to be 0.4 Mbps, a target bit rate of video data is set to 11.5 Mbps. In this manner, efficient dubbing making the best use of the spare capacity of the BD becomes possible. A recorder having such large-capacity media as HDD and BD is designed so that a target bit rate is determined in the above manner to cause the bit rate to converge within a certain time (in the order of several minutes). 
     If an additional data component is added in the above case, however, dubbing contents to fit them exactly in the spare capacity of the BD becomes difficult. This is because that the bit rate of additional data cannot be estimated in advance as the bit rate of audio data is. For example, when the bit rate of (additional data+audio data) is determined to be 5.0 Mbps in the above case, a target bit rate of video data is set to 11.9−5.0=6.9 Mbps. If, however, the bit rate of (additional data+audio data) is actually 6.0 Mbps, the total bit rate is 6.0+6.9=12.9 Mbps, which indicates a situation where the contents are not stored completely in the spare capacity of the BD (11.9 Mbps, 10 Gbytes). Contrary to that, if the bit rate of the data component (additional data+audio data) is actually 1.0 Mbps, an unused capacity is left over, which is calculated at (11.9−7.9)/11.9×10=3.36 GBytes. 
     The present invention was conceived in view of the above circumstances, and it is therefore the object of the present invention to provide a recording apparatus that when changing the bit rate of an input stream to record the input stream changed in bit rate on a recording medium, carries out recording while keeping additional data, such as subtitles and weather reports, intact and considering a spare capacity of the recording medium. 
     Means for Solving the Problems 
     To solve the problems, a first technical means of the present invention is a recording apparatus that changes a bit rate of an input stream including video data, audio data, and additional data to record the input stream change in bit rate, comprising: a video target bit rate setting means that calculates a target total bit rate of the input stream based on a recording time of the input stream and a spare capacity of a recording medium on which the input stream is recorded, the video target bit rate setting means setting a target bit rate of the video data for the calculated target total bit rate; and a total bit rate measuring means that calculates an actual total bit rate of the input stream after the start of bit rate change based on the target bit rate of the video data, wherein the video target bit rate setting means adjusts the target bit rate of the video data so that the input stream including the additional data is stored in the spare capacity of the recording medium, based on a difference between the actual total bit rate and the target total bit rate. 
     A second technical means is the recording apparatus as defined in the first technical means, wherein when the actual total bit rate is larger than the target total bit rate, the video target bit rate setting means lowers a target bit rate of the video data by a difference between the actual total bit rate and the target total bit rate. 
     A third technical means is the recording apparatus as defined in the first technical means, wherein when the actual total bit rate is smaller than the target total bit rate, the video target bit rate setting means raises a target bit rate of the video data by a difference between the actual total bit rate and the target total bit rate. 
     A fourth technical means is the recording apparatus as defined in any one of the first to third technical means, wherein the target total bit rate is composed of a target bit rate of the video data and an estimated bit rate set on the audio data and the additional data. 
     A fifth technical means is the recording apparatus as defined in any one of the first to fourth technical means, wherein when changing a target bit rate of the video data, the video target bit rate setting means repeatedly adjusts the target bit rate by a given rate at every given time to cause the actual total bit rate to converge onto the target total bit rate. 
     A sixth technical means is the recording apparatus as defined in any one of the first to fifth technical means, wherein the total bit rate measuring means counts number of packets of the input stream, multiplies the counted number of packets by a data size per packet, and divides a data size given by the multiplication by a recording time of the input stream to calculate an actual total bit rate of the input stream. 
     EFFECT OF THE INVENTION 
     According to the present invention, when an input stream changed in bit rate is recorded on a recording medium, the input stream is recorded as additional data, such as subtitles and weather reports, is kept intact and a spare capacity of the recording medium is considered. This allows video data, audio data, and additional data to be efficiently stored in the spare capacity of the recording medium. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of a configuration example of a recording apparatus according to one embodiment of the present invention; 
         FIG. 2  is an explanatory diagram of an example of a bit rate change process by the recording apparatus of the present invention; 
         FIG. 3  is an explanatory diagram of a working example in which contents (TS file) recorded on an HDD in a DR mode are changed in bit rate and are dubbed onto a BD; 
         FIG. 4  is an explanatory diagram of a bit rate change process by a conventional recording apparatus; and 
         FIG. 5  is an explanatory diagram of a bit rate change process by a conventional recording apparatus. 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     Preferred embodiments of a recording apparatus of the present invention will now be described with reference to the accompanying drawings. 
       FIG. 1  is a block diagram of a configuration example of a recording apparatus according to one embodiment of the present invention. A recording apparatus  10  includes a tuner  12 , a transcoder  13 , an input/output interface (input/output I/F)  14  that inputs/outputs (writes/reads) data to/from an external recording medium (BD, DVD, etc.) attached thereto, a control portion  15  composed of a CPU, ROM, etc., that controls overall processing by the apparatus, a decoder  16 , an HDD (Hard Disc Drive)  17 , a remote controller receiving portion  18  having a light-receiving portion that receives an optical operation signal from an operation input portion provided as a remote controller, etc., a display/output portion  19  that outputs a stream received via an antenna  11  or a video-recorded stream to an externally connected display device not depicted (such a display means as CRT device, plasma display, liquid crystal display, and organic/nonorganic EL device), and an audio output portion  20  connected to a speaker of the display device, an external speaker, etc. 
     The recording apparatus of  FIG. 10  has a configuration capable of receiving both analog broadcasting waves and digital broadcasting waves, but may have a configuration capable of receiving only one of the analog broadcasting waves and the digital broadcasting waves. The recording apparatus  10  can be used as, for example, a hard disc recorder, BD (Blu-Ray) recorder, or DVD recorder having a digital tuner built therein, a BD recorder or DVD recorder having a hard disc integrated therein, a hard disc recorder, BD recorder, or DVD recorder to which an external tuner is connectible, and a BD recorder or DVD recorder having a hard disc integrated therein. When an external digital tuner, such as STB (Set Top Box), is connected to the recording apparatus, the tuner  12  may be dispensed with. 
     While an HD (Hard Disc) and such a portable recording medium as BD and DVD are applicable as a recording medium, the recording medium is not limited to these mediums. Every recording medium capable of recording streams is applicable to the recording apparatus. A stream is, for example, an MPEG-2TS, which is composed mainly of video data, audio data, and additional data. The additional data is additional data (text, image) other than video/audio data, and includes, for example, subtitles, weather reports, etc. 
     When a digital broadcast is viewed using the recording apparatus  10 , the tuner  12  demodulates a high-frequency signal (digital modulated signal) coming in through the antenna  11  to input the demodulated signal to the decoder  16 . The decoder  16  decodes the input demodulated signal into a video signal and an audio signal, and then generates a display control output signal from the decoded signal to output the display control output signal to the display/output portion  19  while generates an audio control output signal from the decoded signal to output the audio control output signal to the audio output portion  20 . The display control output signal coming out of the display/output portion  19  is input to a display device, such as a TV set, connected to the recording apparatus  10 , while the audio control output signal coming out of the audio output portion  20  is input to a speaker of the display device connected to the recording apparatus  10 . The user is thus able to view a digital broadcasting program corresponding to the display control output signal and audio control output signal on a display screen and the speaker incorporated in the display device. 
     When an analog broadcasting program is recorded using the recording apparatus  10 , the tuner  12  demodulates a high-frequency signal (analog modulated signal) coming in through the antenna  11  to encode the demodulated signal through an encoder (not depicted). The tuner  12  then transforms the encoded data into data of a format adapted for recording (stream) to record the data on various recoding media, such as the HDD  17  and BD, as video-recorded data. 
     When a digital broadcasting program is recorded using the recording apparatus  10 , the tuner  12  demodulates a high-frequency signal (digital modulated signal) coming in through the antenna  11  and records the demodulated signal on various recoding media, such as the HDD  17  and BD. 
     When a program title video-recorded on the HDD  17 , BD, etc., is reproduced by the recording apparatus  10 , the decoder  16  decodes data video-recorded on the HDD  17 , BD, etc., and then transforms the decoded data into data of a format for video output to output the data to the display/output portion  19  while transforms the decoded data into data of a format for audio output to output the data to the audio output portion  20 . A display control output signal coming out of the display/output portion  19  is input to the display device, such as a TV set, connected to the recording apparatus  10 , while an audio control output signal coming out of the audio output portion  20  is input to the speaker of the display device connected to the recording apparatus  10 . The user is thus able to view a video-recorded title corresponding to the display control output signal and audio control output signal on the display screen and the speaker incorporated in the display device. 
     Having the transcoder  13 , the recording apparatus  10  is capable of not recording digital broadcasting waves (input streams) directly on the HDD  17 , BD, etc., but recording the broadcasting waves after changing their bit rate while keeping their MPEG-2TS format intact or after changing their video data format or audio data format. For example, the recording apparatus  10  is able to real-time transcode HDTV video data in the MPEG-2TS format transmitted in ground-wave digital broadcasting into MPEG-4AVC/H264 format data. 
     The main feature of the present invention is to carry out recording while keeping additional data, such as subtitles and weather reports, intact and considering a spare capacity of a recording medium when changing a bit rate of an input stream to record the input stream changed in bit rate on the recording medium. To achieve a configuration for this, the recording apparatus  10  includes the control portion  15  equivalent to a video target bit rate setting means that calculates a target total bit rate of an input stream based on a recording time of the input stream and a spare capacity of a recording medium (HDD  17 , BD, etc.) on which the input stream is recorded and that sets a target bit rate of video data for the calculated target total bit rate, and the transcoder  13  equivalent to a total bit rate measuring means that calculates an actual total bit rate of the input stream after the start of bit rate change based on the target bit rate of the video data. The control portion  15  adjusts the target bit rate of the video data so that the input stream including the additional data is stored exactly in the spare capacity of the recording medium, based on a difference between the actual total bit rate and the target total bit rate. 
       FIG. 2  is an explanatory diagram of an example of a bit rate change process by the recording apparatus  10  of the present invention. The recording apparatus  10  serves as a recorder, and only the principal part configuration (tuner  12 , transcoder  13 , control portion  15 ) of the recording apparatus  10  is depicted. In this example, because the transcoder  13  is connected to the control portion  15  in the form of PCI (Peripheral Components Interconnect), a TS from the tuner  12  invariably goes through the control portion  15 . Another example of a system connection, however, may be provided such that a TS from the tuner  12  is received directly by the transcoder  13  which is connected to the control portion  15  for TS input/output. 
     In  FIG. 2 , the tuner  12  inputs a MPEG-2TS (Transport Stream) to the control portion  15  (S 1 ). The MPEG-2TS is composed mainly of video data, audio data, and additional data. The control portion  15  outputs the MPEG-2TS including the additional data to the transcoder  13  (S 2 ). The transcoder  13  then outputs an AVCTS composed of the video data, audio data, and additional data to the control portion  15  (S 3 ). The control portion  15  records the AVCTS compressed by the transcoder  13  on the HDD  17  or BD. In this manner, the AVCTS compressed by the transcoder  13  includes the additional data, which means that the additional data is not discarded by bit rate change. 
     A working example of changing a bit rate of contents (TS file) recorded in the DR mode on the HDD  17  and dubbing the contents on the BD will then be described referring to  FIG. 3 . 
     In  FIG. 3 ,  21  denotes a target bit rate of video data (hereinafter “video target bit rate”),  22  denotes an estimated bit rate of (audio data+additional data) (hereinafter “audio/additional estimated bit rate),  23  denotes an actual bit rate of the (audio data+additional data) (hereinafter “audio/additional actual bit rate”), and  24  denotes a post-change bit rate of the video data having undergone bit rate change (hereinafter “video post-change bit rate”). A condition for dubbing is the same as the condition in the conventional case where a spare capacity of the BD is 10 GBytes and a recording time of the contents is 2 hours. 
     In the above description, the recording time of the contents is the time required for recording the contents, and is acquired, for example, from SI (Service Information) added to the contents, an electronic program list, etc. The spare capacity of the recording medium means the spare capacity available for recording in the HDD  17  or BD, which is under control by the control portion  15 . The spare capacity does not always have to be the whole of the spare capacity of the recording medium, but may be part of the spare capacity. For example, when the total capacity of the BD is 20 GBytes, 10 GBytes out of 20 GBytes may be determined to be the spare capacity. 
     The relation between a target total bit rate B 1  of  FIG. 3  (A), an actual total bit rate B 2  of  FIG. 3  (B), and a post-change total bit rate B 3  of  FIG. 3  (C) is as follows. 
       Target total bit rate=video target bit rate+audio/additional estimated bit rate  (1)
 
       Actual total bit rate=video target bit rate+audio/additional actual bit rate  (2)
 
       Post-change total bit rate=video post-change bit rate+audio/additional actual bit rate  (3)
 
     In  FIG. 3 , at the start of dubbing, the recording apparatus  10  sets the audio/additional estimated bit rate  22  for the audio data and additional data. In this example, the audio/additional estimated bit rate  22  is set to 2.0 Mbps. This audio/additional estimated bit rate  22  is a temporary set value for determining the video target bit rate  21 . For example, actual bit rates of (audio data+additional data) may be measured on various contents to set the average of the measurements as the audio/additional estimated bit rate  22 . 
     Subsequently, based on the recording time of the contents and the spare capacity of the BD on which the contents are recorded, the target total bit rate B 1  of the contents is calculated, and the video target bit rate  21  is set for the calculated target total bit rate B 1 . In this example, with the recording time of the contents determined to be 2 hours and the spare capacity of the BD determined to be 10 GBytes, as in the above description, the target total bit rate B 1  is calculated at 11.9 Mbps. The video target bit rate  21  is calculated by subtracting the audio/additional estimated bit rate  22  from the target total bit rate B 1 . Hence, in this example, the video target bit rate  21  is determined to be 11.9−2.0=9.9 Mbps. This bit rate relation is depicted in  FIG. 3(A) . 
     Subsequently, the recording apparatus  10  measures the actual total bit rate B 2  at about a time at which the bit rate converges after an elapse of a given time (approximately 10 minutes) from the start of bit rate change based on the video target bit rate  21 . The following methods are conceivable as methods of calculating the actual total bit rate B 2 . 
     (a) The transcoder  13  calculates the actual total bit rate B 2 , i.e., the total bit rate of the AVCTS to report the calculated actual total bit rate B 2  regularly to the control portion  15 . 
     (b) The transcoder  13  calculates the actual total bit rate B 2  to write the actual total bit rate B 2  to an internal register, and the control portion  15  reads the actual total bit rate B 2  in proper timing out of the internal register. 
     (c) The control portion  15  counts data (AVCTS) from the transcoder  13 , and divides the file size of data accumulated from the start of video-recoding by a recording time to calculate the actual total bit rate B 2 . 
     (d) The control portion  15  counts the number of content packets transferred by DMA (Direct Memory Access) transfer and multiplies the counted number of packets by a data size per packet transfer (data size of each packet) to calculate a file size, and divides the file size by a recording time of the TS file to calculate the actual total bit rate B 2 . 
     In the cases of (a) and (b), the transcoder  13  functions as a total bit rate measuring means. In the cases of (c) and (d), the control portion  15  functions as the total bit rate measuring means, thus able to calculate the actual total bit rate B 2  even if failing to receive a report of the actual total bit rate B 2  from the transcoder  13 . 
     In this manner, the actual total bit rate B 2  is calculated, and the video target bit rate  21  is subtracted from the actual total bit rate B 2  to give the audio/additional actual bit rate  23 . In this example, the actual total bit rate B 2  is 14.9 Mbps, from which the video target bit rate  21  of 9.9 Mbps is subtracted to calculate the audio/additional actual bit rate  23  at 5.0 Mbps. That is, the audio/additional actual bit rate  23  is equivalent to a difference between the actual total bit rate B 2  and the video target bit rate  21 , and this difference is regarded as the bit rate of the audio/additional data component. This bit rate relation is depicted in  FIG. 3(B) . 
       FIGS. 3(A) and 3(B)  leads to an estimation that the contents are not stored completely in the spare capacity of the BD when the actual total bit rate B 2  is larger than the target total bit rate B 1 . In such a case, the control portion  15  makes adjustment to lower the video target bit rate  21  by a difference between the actual total bit rate B 2  and the target total bit rate B 1 , that is, a difference between the audio/additional actual bit rate  23  and the audio/additional estimated bit rate  22 . In this example, the audio/additional actual bit rate  23  is 5 Mbps and the audio/additional estimated bit rate  22  is 2 Mbps, so that the difference between both bit rates is 3 Mbps. This difference of 3 Mbps is subtracted from the video target bit rate  21  of 9.9 Mbps. Hence the video target bit rate  21  is lowered to 6.9 Mbps, which makes the post-change total bit rate B 3  equal to the target total bit rate B 1 . As a result, the contents with the recording time of 2 hours including the additional data can be stored in full use of the spare capacity (10 GBytes) of the BD. This bit rate relation is depicted in  FIG. 3(C) . 
     When the video target bit rate  21  is lowered to 6.9 Mbps, rapidly lowering the bit rate results in a sharp deterioration in image quality, which gives the user a strange feeling. It is, therefore, preferable to take a devised approach, such as lowering the bit rate by 0.5 Mbps for every 2 minutes, to carry out bit rate matching. Following bit rate matching, the actual total bit rate B 2  is monitored continuously to carry out dubbing to store the contents completely in the spare capacity of the BD in the end. 
     Contrary to the above example, when the actual total bit rate B 2  is smaller than the target total bit rate B 1  and the contents are estimated to be well within the spare capacity of the BD, the control portion  15  makes adjustment to raise the video target bit rate  21  by a difference between the audio/additional actual bit rate  23  and the audio/additional estimated bit rate  22 . For example, when the audio/additional actual bit rate  23  is 1 Mbps, since the audio/additional estimated bit rate  22  is 2 Mbps, the difference between both bit rates is calculated at 1 Mbps. This difference of 1 Mbps is added to the video target bit rate  21  of 9.9 Mbps. Hence the video target bit rate  21  is raised to 10.9 Mbps, which makes the post-change total bit rate B 3  equal to the target total bit rate B 1 . As a result, the contents with the recording time of 2 hours including the additional data can be stored in full use of the spare capacity (10 GBytes) of the BD. 
     In this case, raising the video target bit rate  21  from 9.9 Mbps to 10.9 Mbps increases the volume of information, thus improves the image quality. Raising the bit rate all at once, therefore, may be allowed. Nevertheless, to avoid giving the user a strange feeling, for example, a devised approach, such as raising the bit rate by 0.5 Mbps for every 2 minutes, may be taken to carry out bit rate matching. Following bit rate matching, the actual total bit rate B 2  is monitored continuously, as in the above example, to carry out dubbing to store the contents completely in the spare capacity of the BD in the end. 
     In this manner, when the video target bit rate  21  is changed, the control portion  15  repeatedly adjusts the video target bit rate  21  by a given rate at every given time (by a feedback process) to be able to cause the actual total bit rate B 2  to converge onto the target total bit rate B 1  in the end. By repeatedly carrying out the process of adjusting the video target bit rate  21 , the contents changed in bit rate including the additional are stored precisely in the spare capacity of the BD in carrying the optimum dubbing. 
     While the case of storing contents including additional data in full use of a spare capacity of a recording medium has been described so far, this is not the only case. For example, a bit rate may be adjusted so that the contents including additional data are stored in part of the spare capacity of the recording medium. 
     According to the present invention, contents changed in bit rate including additional data can be stored precisely in a spare capacity set in a recording medium, such as HDD, BD, and DVD. This allows a user to reproduce the additional data for use and enables accurate control of the spare capacity of the recording medium. 
     EXPLANATIONS OF REFERENCE NUMERALS 
     
         
           1  recording medium 
           11  antenna 
           12  tuner 
           13  transcoder 
           14  input/output I/F 
           15  control portion 
           16  decoder 
           17  HDD 
           18  remote controller receiving portion 
           19  display/output portion 
           20  audio output portion