Patent Publication Number: US-2021168365-A1

Title: Method and device for transmission of video data of different dynamic ranges

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 15/551,196, filed Aug. 15, 2017, which is a national phase application of International Application No. PCT/JP2016/058369, filed on Mar. 16, 2016, which is based on and claims priority to Japanese Application No. 2015-061767, filed on Mar. 24, 2015. The entire contents of each of the above-identified documents are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present technology relates to a transmission device, a transmission method, a reception device, and a reception method, and more particularly to a transmission device, etc. configured to transmit a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics while switching the transmission video data. 
     BACKGROUND ART 
     In related art, there have been attempts to transmit transmission video data obtained by applying high dynamic range opto-electrical conversion to high dynamic range video data. Hereinafter, high dynamic range will be referred to as “HDR” where appropriate. For example, Non-Patent Document 1 teaches HDR opto-electrical transfer characteristics (new gamma characteristics) including regions compatible with conventional opto-electrical transfer characteristics (gamma characteristics) for reception with conventional receivers. 
     CITATION LIST 
     Non-Patent Document 
     
         
         NON-PATENT DOCUMENT 1: Tim Borer, “Non-Linear Opto-Electrical Transfer Functions for High Dynamic Range Television”, Research &amp; Development White Paper WHP 283, July 2014 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     An object of the present technology is, in case where a plurality of transmission video data having predetermined opto-electrical transfer characteristics are switched therebetween and transmitted, to appropriately perform processes for obtaining image data for display from the transmission video data at a receiver side. 
     Solutions to Problems 
     A concept of the present technology lies in a transmission device A transmission device including; 
     an encoding unit configured to encode transmission video data obtained by switching between a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics to obtain a video stream; 
     a transmission unit configured to transmit a container in a predetermined format containing the video stream; and an information insertion unit configured to insert, into the container, identification information representing a kind of a transmission video data in the video stream contained in the container, such that the identification information indicates a kind of transmission video data resulting from switching, from a timing a predetermined amount of time or longer before a timing of the switching. 
     In the present technology, transmission video data obtained by switching between a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics are encoded by the encoding unit, and a video stream is obtained. A container in a predetermined format containing the video stream is transmitted by the transmission unit. For example, the container may be a TS stream or an MMT stream. 
     For example, the plurality of kinds of transmission video data may include: first transmission video data having a standard dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data; and second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data. 
     In addition, for example, the plurality of kinds of transmission video data may include: first transmission video data having a high dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data; and second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with a standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data and performing dynamic range conversion on the video data resulting from the opto-electrical conversion, the dynamic range conversion being based on conversion information for converting a value of data converted with the standard dynamic range opto-electrical transfer characteristic into a value of data converted with the high dynamic range opto-electrical transfer characteristic. 
     In addition, for example, the plurality of kinds of transmission video data may include: first transmission video data having a standard dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data; second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data; and third transmission video data having a high dynamic range opto-electrical transfer characteristic, the third transmission video data being obtained by performing opto-electrical conversion with a standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data and performing dynamic range conversion on the video data resulting from the opto-electrical conversion, the dynamic range conversion being based on conversion information for converting a value of data converted with the standard dynamic range opto-electrical transfer characteristic into a value of data converted with the high dynamic range opto-electrical transfer characteristic. 
     Identification information representing the kind of transmission video data included in the video stream contained in the container is inserted into the container by the information insertion unit, such that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing. For example, the information insertion unit further may further insert, into the container, information on a reference level being a reference luminance level or information on branch level being a luminance level at which a trajectory followed by curves of a standard dynamic range opto-electrical transfer characteristic and a high dynamic range opto-electrical transfer characteristic bifurcates. 
     As described above, according to the present technology, identification information representing the kind of transmission video data included in the video stream contained in the container is inserted into the container, such that the identification information indicates the kind of transmission videod at a resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing. This allows the receiver side to recognize that the kind of transmission video data will be switched and further recognize the kind of transmission video data resulting from the switching, from the timing that is a predetermined amount of time or longer before the switching timing, and allows a process of obtaining image data for display from the transmission video data to be performed smoothly and appropriately even when the kind of transmission video data is switched. 
     Furthermore, another concept of the present technology lies in a reception device including: a reception unit configured to receive a container in a predetermined format containing a video stream obtained by encoding transmission video data, in which 
     the transmission video data is an output of switching between a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics, 
     in the container, identification information representing a kind of transmission video data of the video stream contained by the container is inserted such that the identification information indicates the kind of transmission video data resulting from switching, from a timing a predetermined amount of time or longer before a timing of the switching, and 
     the reception device further includes: 
     a decoding unit configured to decode the video stream to obtain transmission video data; and 
     a processing unit configured to perform an electro-optical conversion process based on the identification information and display performance on the transmission video data obtained by the decoding unit, to obtain image data for display. 
     According to the present technology, a container in a predetermined format containing a video stream obtained by encoding transmission video data is received by the reception unit. Note that the transmission video data are an output of switching between a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics, and that identification information representing a kind of transmission video data included in the video stream contained in container is inserted into the container such that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing. 
     The video stream is decoded by the decoding unit, and transmission video data are obtained. An electro-optical conversion process based on the identification information and display performance is then performed by the processing unit on the transmission video data obtained by the decoding unit, and image data for display are obtained. 
     For example, the plurality of kinds of transmission video data may include: first transmission video data having a standard dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data; and second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data, when the display performance is in a high dynamic range and: in a case where the transmission video data are the first transmission video data, the processing unit may perform dynamic range conversion on the transmission video data and then perform an electro-optical conversion process with the high dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display, or in a case where the transmission video data are the second transmission video data, the processing unit may perform electro-optical conversion with the high dynamic range electro-optical transfer characteristic on the transmission video data to obtain the image data for display, and when the display performance is in a standard dynamic range and: in a case where the transmission video data are the first transmission video data, the processing unit may perform electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the transmission video data to obtain the image data for display, or in a case where the transmission video data are the second transmission video data, the processing unit may perform dynamic range conversion on the transmission video data and then perform electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display. 
     In addition, for example, the plurality of kinds of transmission video data may include: first transmission video data having a high dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data; and second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with a standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data and performing dynamic range conversion on the video data resulting from the opto-electrical conversion, the dynamic range conversion being based on conversion information for converting a value of data converted with the standard dynamic range opto-electrical transfer characteristic into a value of data converted with the high dynamic range opto-electrical transfer characteristic, when the display performance is in a high dynamic range and: in a case where the transmission video data are either of the first transmission video data and the second transmission video data, the processing unit may perform electro-optical conversion with the high dynamic range electro-optical transfer characteristic on the transmission video data to obtain the image data for display, and when the display performance is in a standard dynamic range and: in a case where the transmission video data are the first transmission video data, the processing unit may perform dynamic range conversion with a first conversion characteristic on the transmission video data and then perform electro-optical conversion with the standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display, or in a case where the transmission video data are the second transmission video data, the processing unit may perform dynamic range conversion with a second conversion characteristic on the transmission video data and then perform electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display. 
     In addition, for example, the plurality of kinds of transmission video data may include: first transmission video data having a standard dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data; second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data; and third transmission video data having a high dynamic range opto-electrical transfer characteristic, the third transmission video data being obtained by performing opto-electrical conversion with a standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data and performing dynamic range conversion on the video data resulting from the opto-electrical conversion, the dynamic range conversion being based on conversion information for converting a value of data converted with the standard dynamic range opto-electrical transfer characteristic into a value of data converted with the high dynamic range opto-electrical transfer characteristic, when the display performance is in a high dynamic range and: in a case where the transmission video data are the first transmission video data, the processing unit may perform dynamic range conversion on the transmission video data and then perform electro-optical conversion with a high dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display, or in a case where the transmission video data are the second transmission video data or the third transmission video data, the processing unit may perform electro-optical conversion with a high dynamic range electro-optical transfer characteristic on the transmission video data to obtain the image data for display, and when the display performance is in a standard dynamic range and: in a case where the transmission video data are the first transmission video data, the processing unit may perform electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the transmission video data to obtain the image data for display, in a case where the transmission video data are the second transmission video data, the processing unit may perform dynamic range conversion with a first conversion characteristic on the transmission video data and then perform electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display, or in a case where the transmission video data are the third transmission video data, the processing unit may perform dynamic range conversion with a second conversion characteristic on the transmission video data and then perform electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display. 
     As described above, according to the present technology, identification information representing a kind of transmission video data included in the video stream contained in container is inserted into the container such that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing, and an electro-optical conversion process based on the identification information and display performance is performed on transmission video data so that image data for display are obtained. The identification information allows recognition that the kind of transmission video data will be switched and further allows recognition of the kind of transmission video data resulting from the switching, from the timing that is a predetermined amount of time or longer before the switching timing, which allows an electro-optical conversion process of obtaining image data for display from the transmission video data to be performed smoothly and appropriately even when the kind of transmission video data is switched. 
     Effects of the Invention 
     According to the present technology, in a case where a plurality of transmission video data having predetermined opto-electrical transfer characteristics are switched therebetween and transmitted, processes for obtaining image data for display from the transmission video data can be appropriately performed at a receiver side. Note that the effects mentioned herein are exemplary only and are not limiting, and additional effects may also be produced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating an example configuration of a transmission/reception system according to an embodiment. 
         FIG. 2  is a block diagram illustrating an example configuration of a service transmission system. 
         FIG. 3  is a graph for explaining opto-electrical transfer characteristics. 
         FIG. 4  is a figure for explaining the relation between a timing of switching transmission video data and a timing of inserting identification information for identifying transmission video data resulting from the switching. 
         FIG. 5  is a table describing an example structure of HDR descriptor_type1. 
         FIG. 6  is a table describing an example structure of HDR descriptor_type3. 
         FIG. 7  is a figure describing details of major information in the example structures of the descriptors. 
         FIG. 8  is a diagram illustrating an example of a structure of an MPEG-2 transport stream (TS structure). 
         FIG. 9  is a diagram illustrating an example of a structure of an MMT stream (MMT structure). 
         FIG. 10  is a block diagram illustrating another example configuration of a service transmission system. 
         FIG. 11  is a graph for explaining operation of a dynamic range conversion unit in the service transmission system. 
         FIG. 12  is a graph f or explaining operation of the dynamic range conversion unit in the service transmission system. 
         FIG. 13  is a table describing an example structure of HDR descriptor_type2. 
         FIG. 14  is a diagram illustrating an example of a structure of an MPEG-2 transport stream (TS structure). 
         FIG. 15  is a diagram illustrating an example of a structure of an MMT stream (MMT structure). 
         FIG. 16  is a block diagram illustrating another example configuration of a service transmission system. 
         FIG. 17  is a table describing an example structure of a dynamic range conversion descriptor. 
         FIG. 18  is a figure describing details of major information in the example structure of the dynamic range conversion descriptor. 
         FIG. 19  is a diagram illustrating an example of a structure of an MPEG-2 transport stream (TS structure). 
         FIG. 20  is a diagram illustrating an example of a structure of an MMT stream (MMT structure). 
         FIG. 21  is a block diagram illustrating an example configuration of a service receiver. 
         FIG. 22  is a graph for explaining operation of an HDR/SDR conversion unit in the service receiver. 
         FIG. 23  is a graph for explaining operation of the HDR/SDR conversion unit in the service receiver. 
         FIG. 24  is a graph for explaining operation of the HDR/SDR conversion unit in the service receiver. 
         FIG. 25  is a block diagram illustrating another example configuration of a service receiver. 
         FIG. 26  is a graph for explaining operation of an SDR/HDR conversion unit in the service receiver. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     A mode (hereinafter referred to as an “embodiment”) for carrying out the present technology will be described below. Note that the description will be made in the following order. 
     1. Embodiment 
     2. Modifications 
     1. Embodiment 
     [Example Configuration of a Transmission/Reception System] 
       FIG. 1  illustrates an example configuration of a transmission/reception system  10  according to an embodiment. The transmission/reception system  10  includes a service transmission system  100  and a service receiver  200 . The service transmission system  100  generates an MPEG-2 transport stream or an MPEG media transport (MMT) stream as a container, and transmits the transport stream on a broadcast wave or in a packet over a network. 
     A transport stream includes a video stream obtained by switching between a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics and encoding the resulting transmission video data. A transport stream has identification information representing the kind of transmission video data contained in the video stream included in the transport stream, such that the identification information is inserted to indicate the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing. 
     The service receiver  200  receives the transport stream (the MPEG-2 transport stream or the MMT stream) transmitted from service transmission system  100 . The service receiver  200  decodes video stream contained in the transport stream to obtain the transmission video data. The service receiver  200  also performs an electro-optical conversion process based on the identification information inserted in the transport stream and display performance to obtain image data for display. 
     “Example Configuration of Service Transmission System” 
       FIG. 2  illustrates an example configuration of a service transmission system  100 A, which corresponds to the service transmission system  100  of  FIG. 1 . The service transmission system  100 A includes a control unit  101 , a high dynamic range (HDR) opto-electrical transfer unit  103 , a standard dynamic range (SDR) opto-electrical transfer unit  104 , a switch  106 A, an RGB/YCbCr conversion unit  107 , a video encoder  108 , a container encoder  109 , and a transmission unit  110 . 
     The control unit  101  includes a central processing unit (CPU), and controls operation of the respective units of the service transmission system  100 A on the basis of control programs. The HDR opto-electrical transfer unit  103  performs opto-electrical conversion by applying an HDR opto-electrical transfer characteristic to a high-contrast camera output, that is, HDR video data Vh to obtain HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic). The HDR transmission video data are video materials produced by the HDR OETF. 
     The SDR opto-electrical transfer unit  104  performs opto-electrical conversion by applying an SDR opto-electrical transfer characteristic to a standard-contrast camera output, that is, SDR video data Vs to obtain SDR transmission video data (transmission video data having the SDR opto-electrical transfer characteristic). The SDR transmission video data are video materials produced by the SDR OETF. 
     The opto-electrical transfer characteristics will be explained with reference to  FIG. 3 . A solid curve a is an example of an SDR OETF curve representing the SDR opto-electrical transfer characteristic. A solid curve b is an example of an HDR OETF curve representing the HDR opto-electrical transfer characteristic. The horizontal axis represents an input luminance level, P 1  represents the input luminance level at the maximum SDR level, and P 2  represents the input luminance level at the maximum HDR level. 
     In addition, the vertical axis represents a transmitted code value or a relative value of normalized coding level. A relative maximum level M represents the maximum level in HDR transmission and the maximum level in SDR transmission. A reference level G represents the transmission level of the HDR OETF at the input luminance level P 1  at the maximum SDR level, which refers to a so-called reference white level and indicates that a range higher than this level is used for glittering expressions characteristic of the HDR. A branch level B represents a level where the trajectory followed by the SDR OETF curve and the HDR OTF curve bifurcates. Pf represents the input luminance level at the branch level. Note that the branch level B can be any value not smaller than 0. 
     The switch  106 A selectively extracts SDR transmission video data (transmission video data A) obtained by the SDR opto-electrical transfer unit  104  or HDR transmission video data (transmission video data B) obtained by the HDR opto-electrical transfer unit  103 . This switching is performed in units of a program or in units equivalent thereto. 
     The RGB/YCbCr conversion unit  107  converts transmission video data V 1  extracted by the switch  106 A from the RGB domain to the YCbCr (luminance/chrominance) domain. Note that the color space domain is not limited to the RGB domain, and that the luminance/chrominance domain is not limited to the YCbCr. 
     The video encoder  108  encodes the transmission video data V 1 , resulting from the conversion to the YCbCr domain by the RGB/YCbCr conversion unit  107 , in MPEG4-AVC or HEVC, for example, to obtain encoded video data, and generates a video stream (video elementary stream) VS containing the encoded video data. 
     In this process, the video encoder  108  inserts meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , into a region of video usability information (VUI) of an SPS NAL unit of an access unit (AU). 
     In this case, when the transmission video data V 1  are the transmission video data A (the SDR transmission video data obtained by the SDR opto-electrical transfer unit  104 ), the opto-electrical transfer characteristic of the transmission video data V 1  is the opto-electrical transfer characteristic of the SDR opto-electrical transfer unit  104 . In contrast, when the transmission video data V 1  are the transmission video data B (the HDR transmission video data obtained by the HDR opto-electrical transfer unit  103 ), the opto-electrical transfer characteristic of the transmission video data V 1  is the opto-electrical transfer characteristic of the HDR opto-electrical transfer unit  103 . 
     The container encoder  109  generates a transport stream (an MPEG-2 transport stream or an MMT stream) containing the video stream VS generated by the video encoder  108 . The transmission unit  110  transmits the transport stream on a broadcast wave or in a packet over a network to the service receiver  200 . 
     For this process, the container encoder  109  inserts identification information representing the transmission video data A or the transmission video data B into the transport stream. In this case, the container encoder  109  inserts the identification information into the transport stream so that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing. The insertion of the identification information is controlled in this manner allows the receiver side to be informed of dynamic switching of transmission video data. 
       FIG. 4  illustrates the relation between the timings Sn (S 0 , S 1 , S 2 , . . . ) of switching between the transmission video data A (SDR service) and the transmission video data B (HDR service) and the timings Tn (T 0 , T 1 , T 2 , . . . ) of insertion of the identification information for identifying the transmission video data resulting from switching. The timing Tn is a timing of t (predetermined amount of time) or more before the timing Sn such that the expression (1) below is satisfied. Note that the example illustrated in  FIG. 4  shows a case in which Sn−Tn=t (where t is a positive value). 
         Sn−Tn≥t   (1)
 
     The container encoder  109  inserts a descriptor of HDR descriptor_type1 or HDR descriptor_type3, which describes identification information and which is newly defined, for example. The descriptor is inserted under a program map table (PMT) when the transport stream is an MPEG-2 transport stream, or inserted under an MMT package table (MP table) when the transport stream is an MMT stream, for example. 
       FIG. 5  shows an example structure (syntax) of HDR descriptor_type1, and  FIG. 6  shows an example structure (syntax) of HDR descriptor_type3, and  FIG. 7  shows details (semantics) of major information in these example structures. 
     The descriptor of HDR descriptor_type1 shown in  FIG. 5  will be explained. An 8-bit field of “descriptor_tag” represents the type of the descriptor, which is the descriptor of HDR descriptor_type1 here. An 8-bit field of “descriptor_length” represents the length (size) of the descriptor, and indicates the number of subsequent bytes as the length of the descriptor. 
     One-bit flag information of “HDR_SDR_flag” indicates that a current stream is an HDR stream or an SDR stream. “1” indicates that the current stream is an HDR stream, and “0” indicates that the current stream is an SDR stream. One-bit flag information of “characteristics_info_flag” indicates whether or not characteristic information is present. “1” indicates that characteristic information is present, and “0” indicates that characteristic information is absent. 
     When “characteristics_info_flag” is “1,” the following field is present. An 8-bit field of “transferfunction” represents an electro-optical transfer characteristic (EOTF characteristics). In other words, this field indicates an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 . For example, “1” indicates “BT.709-5 transfer characteristic (SDR),” “14” indicates “10 bitBT.2020 transfer characteristic (SDR),” “16” indicates “SMPTE 2084 transfer characteristic (HDR1),” and “25” indicates “HDR (HDR2).” Note that “HDR (HDR2)” represents an HDR electro-optical transfer characteristic, which is not a PQ curve but is considered to be partially compatible with the conventional gamma characteristics in luminance/transmission characteristics or to have similar characteristics. 
     An 8-bit field of “reference level” represents the reference level G (see  FIG. 3 ). In this case, a value specified by a value of 0 to 100 in a relative range normalized to a maximum of “1” is described as the reference level G At the receiver side, a result of dividing the value by 100 is recognized as a normalized relative reference level. An 8-bit field of “branch level” represents the branch level B (see  FIG. 3 ). In this case, a value specified by a value of 0 to 100 in a relative range normalized to a maximum of “1” is described as the branch level B. At the receiver side, a result of dividing the value by 100 is recognized as the branch level. 
     In the descriptor of HDR descriptor_type1, the descriptor type information in the “descriptor_tag” field and the information indicating whether the stream is HDR or SDR in the “HDR_SDR_flag” field indicate that the transmission video data V 1  are the transmission video data A or the transmission video data B. 
     The descriptor of HDR descriptor_type3 shown in  FIG. 6  will be explained. An 8-bit field of “descriptor_tag” represents the type of the descriptor, which is the descriptor of HDR descriptor_type3 here. An 8-bit field of “descriptor_length” represents the length (size) of the descriptor, and indicates the number of subsequent bytes as the length of the descriptor. 
     One-bit flag information of “HDR_SDR_flag” indicates that a current stream is an HDR stream or an SDR stream. “1” indicates that the current stream is an HDR stream, and “0” indicates that the current stream is an SDR stream. One-bit flag information of “characteristics_info_flag” indicates whether or not characteristic information is present. “1” indicates that characteristic information is present, and “0” indicates that characteristic information is absent. 
     A 2-bit field of “SDR_mapping_type” indicates whether or not the characteristics of SDR are mapped on the characteristics of HDR. “0” indicates that the characteristics of SDR are not mapped on the characteristics of HDR, that is, the characteristics of SDR are to be transmitted without being mapped on the characteristics of HDR. “1” indicates that the characteristics of SDR are mapped on the characteristics of HDR, that is, the characteristics of SDR are mapped on the characteristics of HDR before being transmitted. In the service transmission system  100 A illustrated in  FIG. 2 , “SDR_mapping_type” is always “0.” 
     When “characteristics_info_flag” is “1,” 8-bit fields of “transferfunction,” “referencelevel,” and “branchlevel” are present similarly to the descriptor of HDR descriptor_type1 shown in  FIG. 5 . 
     In the descriptor of HDR descriptor_type3, the information indicating whether the stream is HDR or SDR in the “HDR_SDR_flag” field and the information indicating whether the SDR characteristics are mapped on the HDR characteristics in the “SDR_mapping_type” field indicate the transmission video data A or the transmission video data B. 
       FIG. 8  illustrates an example of a structure of an MPEG-2 transport stream (TS structure). In this example structure, a PES packet “Video PES” of a video stream identified by PID1 is present. Meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , is inserted into a region of VUI of an SPS of an access unit. 
     The transport stream TS also includes a program map table (PMT) as program specific information (PSI). The PSI is information describing which program each of elementary streams contained in the transport stream belongs to. A program loop describing information related to the entire program is present in the PMT. 
     An elementary stream loop having information related to the elementary streams is present in the PMT. In this example structure, a video elementary stream loop (video ES loop) associated with the video stream is present. In the video elementary stream loop (video ES loop), information such as the stream type, a packet identifier (PID), and the like is arranged in association with the video stream, and a descriptor describing information related to the video stream is also arranged. 
     Assume that the value of “Stream_type” of the video stream is set to a value indicating an HEVC video stream, for example, and that the PID information indicates PID1 assigned to a PES packet “video PES” of the video stream. The descriptor of HDR descriptor_type1 or the descriptor of HDR descriptor_type3 described above is inserted as one of descriptors. 
       FIG. 9  illustrates an example of a structure of an MMT stream (MMT structure). MMT packets of assets such as MMT video and audio are present in an MMT stream. In the example structure illustrated in  FIG. 9 , an MMT packet of a video asset identified by ID 1  is present. Meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , is inserted into a region of VUI of an SPS of an access unit. 
     In addition, message packets such as a packet access (PA) message packet are present in an MMT stream. A PA message packet contains a table such as an MMT packet table (MMT package table). An MP table contains information on each asset. The descriptor of HDR descriptor_type1 or the descriptor of HDR descriptor_type3 described above is inserted. 
     Operation of the service transmission system  100 A illustrated in  FIG. 2  will be briefly explained. HDR video data Vh, which are a high-contrast camera output, are supplied to the HDR opto-electrical transfer unit  103 . In the HDR opto-electrical transfer unit  103 , opto-electrical conversion using the HDR opto-electrical transfer characteristic is performed on the HDR video data Vh, and HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic) are obtained as video materials produced by the HDR OETF. 
     In addition, SDR video data Vs, which are a standard-contrast camera output, are supplied to the SDR opto-electrical transfer unit  104 . In the SDR opto-electrical transfer unit  104 , opto-electrical conversion using the SDR opto-electrical transfer characteristic is performed on the SDR video data Vs, SDR transmission video data (transmission video data having the SDR opto-electrical transfer characteristic) are obtained as video materials produced by the SDR OETF. 
     In the switch  106 A, transmission video data A (SDR transmission video data) obtained by the SDR opto-electrical transfer unit  104  or transmission video data B (HDR transmission video data) obtained by the HDR opto-electrical transfer unit  103  are selectively extracted under the control of the control unit  101 . The thus extracted transmission video data are converted from the RGB domain to the YCbCr (luminance/chrominance) domain by the RGB/YCbCr conversion unit  107 . 
     The transmission video data V 1  resulting from the conversion to YCbCr domain are supplied to the video encoder  108 . In the video encoder  108 , encoding in MPEG4-AVC or HEVC, for example is performed on the transmission video data V 1 , encoded video data are obtained, and a video stream VS containing the encoded video data is generated. In this process, in the video encoder  108 , meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , is inserted into a region of VUI of an SPS NAL unit of an access unit (AU). 
     The video stream VS obtained by the video encoder  108  is supplied to the container encoder  109 . In the container encoder  109 , a transport stream (an MPEG-2 transport stream or an MMT stream) containing the video stream VS generated by the video encoder  108  is generated. The transport stream is transmitted by transmission unit  110  on a broadcast wave or in a packet over a network to the service receiver  200 . 
     For this process, in the container encoder  109 , a descriptor (the descriptor of HDR descriptor_type1 (see  FIG. 5 ) or the descriptor of HDR descriptor_type3 (see  FIG. 6 )) describing identification information representing the transmission video data A or the transmission video data B is inserted into the transport stream that is a container. In this case, in the container encoder  109 , the identification information is inserted so that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time before the switching timing. 
       FIG. 10  illustrates an example configuration of a service transmission system  100 B, which corresponds to the service transmission system  100  of  FIG. 1 . In  FIG. 10 , parts corresponding to those in  FIG. 2  are designated by the same reference numerals, and detailed description thereof will not be repeated as appropriate. The service transmission system  100 B includes a control unit  101 , an HDR opto-electrical transfer unit  103 , an SDR opto-electrical transfer unit  104 , a dynamic range conversion unit  105 , a switch  106 B, an RGB/YCbCr conversion unit  107 , a video encoder  108 , a container encoder  109 , and a transmission unit  110 . 
     The control unit  101  includes a CPU, and controls operation of the respective units of the service transmission system  100 B on the basis of control programs. The HDR opto-electrical transfer unit  103  performs opto-electrical conversion by applying an HDR opto-electrical transfer characteristic to a high-contrast camera output, that is, HDR video data Vh to obtain HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic). The HDR transmission video data are video materials produced by the HDR OETF. 
     The SDR opto-electrical transfer unit  104  performs opto-electrical conversion by applying an SDR opto-electrical transfer characteristic to a standard-contrast camera output, that is, SDR video data Vs to obtain SDR transmission video data (transmission video data having the SDR opto-electrical transfer characteristic). The SDR transmission video data are video materials produced by the SDR OETF. 
     The dynamic range conversion unit  105  performs dynamic range conversion on the SDR transmission video data to obtain HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic). Specifically, the dynamic range conversion unit  105  converts the SDR transmission video data that are video materials produced by the SDR OETF into HDR transmission video data. Note that the dynamic range conversion unit  105  performs the dynamic range conversion on the basis of conversion information for converting the value of data converted with the SDR opto-electrical transfer characteristic to the value of data converted with the HDR opto-electrical transfer characteristic. The conversion information is provided by the control unit  101 , for example. 
     The dynamic range conversion will be further described with reference to  FIG. 11 . A solid curve a is an example of an SDR OETF curve representing the SDR opto-electrical transfer characteristic. A solid curve b is an example of an HDR OETF curve representing the HDR opto-electrical transfer characteristic. The horizontal axis represents an input luminance level, P 1  represents the input luminance level at the maximum SDR level, and P 2  represents the input luminance level at the maximum HDR level. 
     In addition, the vertical axis represents a transmitted code value or a relative value of normalized coding level. A relative maximum level M represents the maximum level in HDR transmission and the maximum level in SDR transmission. A reference level G represents the transmission level of the HDR OETF at the input luminance level P 1  at the maximum SDR level, which refers to a so-called reference white level and indicates that a range higher than this level is used for glittering expressions characteristic of the HDR. 
     A branch level B represents a level where the trajectory followed by the SDR OETF curve and the HDR OETF curve bifurcates. Pf represents the input luminance level at the branch level. Note that the branch level B can be any value not smaller than 0.  FIG. 12  shows an example of a case in which the branch level B is 0. 
     The dynamic range conversion in the dynamic range conversion unit  105  is performed so that data at the branch level B or higher but the relative maximum level M or lower among the SDR transmission video data are converted to have the value of data converted with the HDR opto-electrical transfer characteristic. In this case, the relative maximum level M that is the maximum SDR level is made to be equal to the reference level G. Note that input data not higher than the branch level B are output as output data without any change. 
     Note that the conversion information is in a form of a conversion table or a conversion coefficient. In a case where the conversion information is in a form of a conversion table, the dynamic range conversion unit  105  refers to the conversion table to perform the conversion. On the other hand, in a case where the conversion information is in a form of a conversion coefficient, the dynamic range conversion unit  105  performs the conversion by computation using the conversion coefficient. For example, when the conversion coefficient is represented by C, conversion is performed on input data at the branch level B or higher but the relative maximum level M or lower by the following expression (2). 
       Output data=branch level  B +(input data−branch level  B )* C    (2)
 
     The description refers back to  FIG. 10 , in which the switch  106 B selectively extracts HDR transmission video data (transmission video data B) obtained by the HDR opto-electrical transfer unit  103  or HDR transmission video data (transmission video data C) obtained by the dynamic range conversion unit  105 . 
     The RGB/YCbCr conversion unit  107  converts transmission video data V 1  extracted by the switch  106 B from the RGB domain to the YCbCr (luminance/chrominance) domain. The video encoder  108  encodes the transmission video data V 1 , resulting from the conversion to the YCbCr domain by the RGB/YCbCr conversion unit  107 , in MPEG4-AVC or HEVC, for example, to obtain encoded video data, and generates a video stream VS containing the encoded video data. 
     In this process, the video encoder  108  inserts meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information (transfer function) indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , into a region of VUI of an SPS NAL unit of an access unit (AU). 
     Note that the opto-electrical transfer characteristic of the transmission video data V 1  is the opto-electrical transfer characteristic of the HDR opto-electrical transfer unit  103  both when the transmission video data V 1  are the transmission video data B (the HDR transmission video data obtained by the HDR opto-electrical transfer unit  104 ) and when the transmission video data V 1  are the transmission video data C (the HDR transmission video data are obtained by the dynamic range conversion unit  105 ). 
     The container encoder  109  generates a transport stream (an MPEG-2 transport stream or an MMT stream) containing the video stream VS generated by the video encoder  108 . The transmission unit  110  transmits the transport stream on a broadcast wave or in a packet over a network to the service receiver  200 . 
     For this process, the container encoder  109  inserts identification information representing the transmission video data B or the transmission video data C into the transport stream. In this case, the container encoder  109  inserts the identification information into the transport stream so that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing (see  FIG. 4 ). The insertion of the identification information is controlled in this manner allows the receiver side to be informed of dynamic switching of transmission video data. 
     The container encoder  109  inserts a descriptor of HDR descriptor_type2 or HDR descriptor_type3 described above (see  FIG. 6 ), which describes identification information and which is newly defined, for example. The descriptor is inserted under a program map table when the transport stream is an MPEG-2 transport stream, or inserted under an MP table when the transport stream is an MT stream, for example. 
       FIG. 13  shows an example structure (syntax) of the descriptor of HDR descriptor_type2. An 8-bit field of “descriptor_tag” represents the type of the descriptor, which is the descriptor of HDR descriptor_type2 here. An 8-bit field of “descriptor_length” represents the length (size) of the descriptor, and indicates the number of subsequent bytes as the length of the descriptor. 
     One-bit flag information of “HDR_SDR_flag” indicates that a current stream is an HDR stream or an SDR stream. “1” indicates that the current stream is an HDR stream, and “0” indicates that the current stream is an SDR stream. One-bit flag information of “characteristics_info_flag” indicates whether or not characteristic information is present. “1” indicates that characteristic information is present, and “0” indicates that characteristic information is absent. When “characteristics_info_flag” is “1,” 8-bit fields of “transferfunction,” “referencelevel,” and “branchlevel” are present similarly to the descriptor of HDR descriptor_type1 shown in  FIG. 5 . 
     In the descriptor of HDR descriptor_type2, the type information of the descriptor in the “descriptor_tag” field and the information indicating whether the stream is HDR or SDR in the “HDR_SDR_flag” field indicate whether the transmission video data V 1  are the transmission video data B or the transmission video data C. 
     Note that, in the descriptor of HDR descriptor_type3 (see  FIG. 6 ), which is inserted instead of HDR descriptor_type2, the information indicating whether the stream is HDR or SDR in the “HDR_SDR_flag” field and the information indicating whether the SDR characteristics are mapped on the HDR characteristics in the “SDR_mapping_type” field indicate the transmission video data B or the transmission video data C. 
       FIG. 14  illustrates an example of a structure of an MPEG-2 transport stream (TS structure). In this example structure, a PES packet “Video PES” of a video stream identified by PID1 is present. Meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , is inserted into a region of VUI of an SPS of an access unit. 
     The transport stream TS also includes a program map table (PMT) as program specific information (PSI). The PSI is information describing which program each of elementary streams contained in the transport stream belongs to. A program loop describing information related to the entire program is present in the PMT. 
     An elementary stream loop having information related to the elementary streams is present in the PMT. In this example structure, a video elementary stream loop (video ES loop) associated with the video stream is present. In the video elementary stream loop (video ES loop), information such as the stream type, a packet identifier (PID), and the like is arranged in association with the video stream, and a descriptor describing information related to the video stream is also arranged. 
     Assume that the value of “Stream_type” of the video stream is set to a value indicating an HEVC video stream, for example, and that the PID information indicates PID1 assigned to a PES packet “video PES” of the video stream. The descriptor of HDR descriptor_type2 or the descriptor of HDR descriptor_type3 described above is inserted as one of descriptors. 
       FIG. 15  illustrates an example of a structure of an MMT stream (MMT structure). MMT packets of assets such as MMT video and audio are present in an MMT stream. In the example structure illustrated in  FIG. 9 , an MMT packet of a video asset identified by ID 1  is present. Meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , is inserted into a region of VUI of an SPS of an access unit. 
     In addition, message packets such as a packet access (PA) message packet are present in an MMT stream. A PA message packet contains a table such as an MMT packet table (MMT package table). An MP table contains information on each asset. The descriptor of HDR descriptor_type2 or the descriptor of HDR descriptor_type3 described above is inserted. 
     Operation of the service transmission system  100 B illustrated in  FIG. 10  will be briefly explained. HDR video data Vh, which are a high-contrast camera output, are supplied to the HDR opto-electrical transfer unit  103 . In the HDR opto-electrical transfer unit  103 , opto-electrical conversion using the HDR opto-electrical transfer characteristic is performed on the HDR video data Vh, and HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic) are obtained as video materials produced by the HDR OETF. 
     In addition, SDR video data Vs, which are a standard-contrast camera output, are supplied to the SDR opto-electrical transfer unit  104 . In the SDR opto-electrical transfer unit  104 , opto-electrical conversion using the SDR opto-electrical transfer characteristic is performed on the SDR video data Vs, SDR transmission video data (transmission video data having the SDR opto-electrical transfer characteristic) are obtained as video materials produced by the SDR OETF. 
     The SDR transmission video data obtained by the SDR opto-electrical transfer unit  104  are supplied to the dynamic range conversion unit  105 . In the dynamic range conversion unit  105 , dynamic range conversion is performed on the SDR transmission video data on the basis of the conversion information (conversion table, conversion coefficient) supplied from the control unit  101 . The dynamic range conversion converts the SDR transmission video data into HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic) (see  FIG. 11 ). 
     In the switch  106 B, transmission video data B (HDR transmission video data) obtained by the HDR opto-electrical transfer unit  103  or transmission video data C (HDR transmission video data) obtained by the dynamic range conversion unit  105  are selectively extracted under the control of the control unit  101 . The thus extracted transmission video data are converted from the RGB domain to the YCbCr (luminance/chrominance) domain by the RGB/YCbCr conversion unit  107 . 
     The transmission video data V 1  resulting from the conversion to YCbCr domain are supplied to the video encoder  108 . In the video encoder  108 , encoding in MPEG4-AVC or HEVC, for example is performed on the transmission video data V 1 , encoded video data are obtained, and a video stream VS containing the encoded video data is generated. In this process, in the video encoder  108 , meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , is inserted into a region of VUI of an SPS NAL unit of an access unit (AU). 
     The video stream VS obtained by the video encoder  108  is supplied to the container encoder  109 . In the container encoder  109 , a transport stream (an MPEG-2 transport stream or an MMT stream) containing the video stream VS generated by the video encoder  108  is generated. The transport stream is transmitted by transmission unit  110  on a broadcast wave or in a packet over a network to the service receiver  200 . 
     For this process, in the container encoder  109 , a descriptor (the descriptor of HDR descriptor_type2 (see  FIG. 13 ) or the descriptor of HDR descriptor_type3 (see  FIG. 6 )) describing identification information representing the transmission video data B or the transmission video data C is inserted into the transport stream that is a container. In this case, in the container encoder  109 , the identification information is inserted so that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing. 
       FIG. 16  illustrates an example configuration of a service transmission system  100 C, which corresponds to the service transmission system  100  of  FIG. 1 . In  FIG. 16 , parts corresponding to those in  FIGS. 2 and 10  are designated by the same reference numerals, and detailed description thereof will not be repeated as appropriate. The service transmission system  100 C includes a control unit  101 , an HDR opto-electrical transfer unit  103 , an SDR opto-electrical transfer unit  104 , a dynamic range conversion unit  105 , a switch  106 C, an RGB/YCbCr conversion unit  107 , a video encoder  108 , a container encoder  109 , and a transmission unit  110 . 
     The control unit  101  includes a CPU, and controls operation of the respective units of the service transmission system  100 C on the basis of control programs. The HDR opto-electrical transfer unit  103  performs opto-electrical conversion by applying an HDR opto-electrical transfer characteristic to a high-contrast camera output, that is, HDR video data Vh to obtain HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic). The HDR transmission video data are video materials produced by the HDR OETF. 
     The SDR opto-electrical transfer unit  104  performs opto-electrical conversion by applying an SDR opto-electrical transfer characteristic to a standard-contrast camera output, that is, SDR video data Vs to obtain SDR transmission video data (transmission video data having the SDR opto-electrical transfer characteristic). The SDR transmission video data are video materials produced by the SDR OETF. 
     The dynamic range conversion unit  105  performs dynamic range conversion on the SDR transmission video data to obtain HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic). Specifically, the dynamic range conversion unit  105  converts the SDR transmission video data that are video materials produced by the SDR OETF into HDR transmission video data. 
     The switch  106 C selectively extracts SDR transmission video data (transmission video data A) obtained by the SDR opto-electrical transfer unit  104 , HDR transmission video data (transmission video data B) obtained by the HDR opto-electrical transfer unit  103 , or HDR transmission video data (transmission video data C) obtained by the dynamic range conversion unit  105 . 
     The RGB/YCbCr conversion unit  107  converts transmission video data V 1  extracted by the switch  106 C from the RGB domain to the YCbCr (luminance/chrominance) domain. The video encoder  108  encodes the transmission video data V 1 , resulting from the conversion to the YCbCr domain by the RGB/YCbCr conversion unit  107 , in MPEG4-AVC or HEVC, for example, to obtain encoded video data, and generates a video stream VS containing the encoded video data. 
     In this process, the video encoder  108  inserts meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information (transfer function) indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , into a region of VUI of an SPS NAL unit of an access unit (AU). 
     In this case, when the transmission video data V 1  are the transmission video data A (the SDR transmission video data obtained by the SDR opto-electrical transfer unit  104 ), the opto-electrical transfer characteristic of the transmission video data V 1  is the opto-electrical transfer characteristic of the SDR opto-electrical transfer unit  104 . In addition, both when the transmission video data V 1  are the transmission video data B (the HDR transmission video data obtained by the HDR opto-electrical transfer unit  104 ) and when the transmission video data V 1  are the transmission video data C (the HDR transmission video data are obtained by the dynamic range conversion unit  105 ), the opto-electrical transfer characteristic of the transmission video data V 1  is the opto-electrical transfer characteristic of the HDR opto-electrical transfer unit  103 . 
     The container encoder  109  generates a transport stream (an MPEG-2 transport stream or an MT stream) containing the video stream VS generated by the video encoder  108 . The transmission unit  110  transmits the transport stream on a broadcast wave or in a packet over a network to the service receiver  200 . 
     For this process, the container encoder  109  inserts identification information representing the transmission video data A, the transmission video data B, or the transmission video data C into the transport stream. In this case, the container encoder  109  inserts the identification information into the transport stream so that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing (see  FIG. 4 ). The insertion of the identification information is controlled in this manner allows the receiver side to be informed of dynamic switching of transmission video data. 
     The container encoder  109  inserts a dynamic range conversion descriptor (dynamic_range_conversion_descriptor), which describes identification information and which is newly defined, for example. The descriptor is inserted under a program map table when the transport stream is an MPEG-2 transport stream, or inserted under an MP table when the transport stream is an MMT stream, for example. 
       FIG. 17  shows an example structure (syntax) of the dynamic range conversion descriptor.  FIG. 18  shows details (semantics) of major information in the example structure. An 8-bit field of “descriptor_tag” represents the type of the descriptor, which is the dynamic range conversion descriptor here. An 8-bit field of “descriptor_length” represents the length (size) of the descriptor, and indicates the number of subsequent bytes as the length of the descriptor. 
     An 8-bit field of “highdynamicrange” indicates that a current stream is an HDR stream or an SDR stream. “1” indicates that the current stream is an HDR stream, and “O” indicates that the current stream is an SDR stream. An 8-bit field of “transferfunction” represents an electro-optical transfer characteristic (EOTF characteristics). In other words, this field indicates an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic (current electro-optical transfer characteristic) of the transmission video data V 1 . For example, “1” indicates “BT.709-5 transfer characteristic (SDR),” “14” indicates “10 bit BT.2020 transfer characteristic (SDR),” “16” indicates “SMPTE 2084 transfer characteristic (HDR1),” and “25” indicates “HDR (HDR2).” Note that “HDR (HDR2)” represents an HDR electro-optical transfer characteristic, which is not a PQ curve but is what is called hybrid gamma. 
     An 8-bit field of “xycolourprimaries” represents a color space. For example, “1” indicates “BT.709-5,” “9” indicates “BT.2020,” and “10” indicates “SMPTE 428 or XYZ.” An 8-bit field of “matrixcoefficients” represents a color matrix coefficient. For example, “1” indicates “BT.709-5,” “9” indicates “BT.2020 non-constant luminance,” and “11” indicates “SMPTE 2085 or Y′D′zD′x.” 
     An 8-bit field of “referencelevel” represents the reference level G (see  FIGS. 3 and 11 ). In this case, a value specified by a value of 0 to 100 in a relative range normalized to a maximum of “1” is described as the reference level G At the receiver side, a result of dividing the value by 100 is recognized as a normalized relative reference level. The relative reference level constitutes a conversion coefficient that is the conversion information for the dynamic range conversion. 
     An 8-bit field of “branchlevel” represents the branch level B (see  FIGS. 3 and 11 ). In this case, a value specified by a value of 0 to 100 in a relative range normalized to a maximum of “1” is described as the branch level B. At the receiver side, a result of dividing the value by 100 is recognized as the branch level. 
     An 8-bit field of “original_transferfunction” represents an original electro-optical transfer characteristic. “1” indicates “BT.709-5 transfer characteristic (SDR).” “14” indicates “10 bit BT.2020 transfer characteristic (SDR).” “16” indicates “SMPTE 2084 transfer characteristic (HDR1).” “25” indicates “HDR (HDR2).” 
     In the descriptor of dynamic_range_conversion_descriptor, the information indicating whether the stream is HDR or SDR in the “highdynamicrange” field, the information indicating the current electro-optical transfer characteristic in the “transferfunction” field, and the information indicating the original electro-optical transfer characteristic in the “original_transferfunction” field indicate whether the transmission video data V 1  are the transmission video data A, the transmission video data B, or the transmission video data C. 
     In a case where the transmission video data V 1  are the transmission video data A, an SDR stream is indicated, and the current electro-optical transfer characteristic and the original electro-optical transfer characteristic indicate the same SDR electro-optical transfer characteristic. Alternatively, in a case where the transmission video data V 1  are the transmission video data B, an HDR stream is indicated, and the electro-optical transfer characteristic and the current electro-optical transfer characteristic indicate the same HDR electro-optical transfer characteristic. Still alternatively, in a case where the transmission video data V 1  are the transmission video data C, an HDR stream is indicated, the original electro-optical transfer characteristic indicates the SDR electro-optical transfer characteristic, but the current electro-optical transfer characteristic indicates the HDR electro-optical transfer characteristic. 
     Note that the descriptor of HDR descriptor_type3 (see  FIG. 6 ) described above can be inserted instead of the dynamic range conversion descriptor. In the descriptor of HDR descriptor_type3, the information indicating whether the stream is HDR or SDR in the “HDR_SDR_flag” field and the information indicating whether the SDR characteristics are mapped on the HDR characteristics in the “SDR_mapping_type” field indicate the transmission video data A, the transmission video data B, or the transmission video data C. 
       FIG. 19  illustrates an example of a structure of an MPEG-2 transport stream (TS structure). In this example structure, a PES packet “Video PES” of a video stream identified by PID1 is present. Meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , is inserted into a region of VUI of an SPS of an access unit. 
     The transport stream TS also includes a program map table (PMT) as program specific information (PSI). The PSI is information describing which program each of elementary streams contained in the transport stream belongs to. A program loop describing information related to the entire program is present in the PMT. 
     An elementary stream loop having information related to the elementary streams is present in the PMT. In this example structure, a video elementary stream loop (video ES loop) associated with the video stream is present. In the video elementary stream loop (video ES loop), information such as the stream type, a packet identifier (PID), and the like is arranged in association with the video stream, and a descriptor describing information related to the video stream is also arranged. 
     Assume that the value of “Stream_type” of the video stream is set to a value indicating an HEVC video stream, for example, and that the PID information indicates PID1 assigned to a PES packet “video PES” of the video stream. The dynamic range conversion descriptor or the descriptor of HDR descriptor_type3 described above is inserted as one of descriptors. 
       FIG. 20  illustrates an example of a structure of an MMT stream (MMT structure). MMT packets of assets such as MMT video and audio are present in an MMT stream. In the example structure illustrated in  FIG. 9 , an MMT packet of a video asset identified by ID 1  is present. Meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , is inserted into a region of VUI of an SPS of an access unit. 
     In addition, message packets such as a packet access (PA) message packet are present in an MMT stream. A PA message packet contains a table such as an MMT packet table (MMT package table). An MP table contains information on each asset. The dynamic range conversion descriptor or the descriptor of HDR descriptor_type3 described above is inserted. 
     Operation of the service transmission system  100 C illustrated in  FIG. 16  will be briefly explained. HDR video data Vh, which are a high-contrast camera output, are supplied to the HDR opto-electrical transfer unit  103 . In the HDR opto-electrical transfer unit  103 , opto-electrical conversion using the HDR opto-electrical transfer characteristic is performed on the HDR video data Vh, and HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic) are obtained as video materials produced by the HDR OETF. 
     In addition, SDR video data Vs, which are a standard-contrast camera output, are supplied to the SDR opto-electrical transfer unit  104 . In the SDR opto-electrical transfer unit  104 , opto-electrical conversion using the SDR opto-electrical transfer characteristic is performed on the SDR video data Vs, SDR transmission video data (transmission video data having the SDR opto-electrical transfer characteristic) are obtained as video materials produced by the SDR OETF. 
     The SDR transmission video data obtained by the SDR opto-electrical transfer unit  104  are supplied to the dynamic range conversion unit  105 . In the dynamic range conversion unit  105 , dynamic range conversion is performed on the SDR transmission video data on the basis of the conversion information (conversion table, conversion coefficient) supplied from the control unit  101 . The dynamic range conversion converts the SDR transmission video data into HDR transmission video data (transmission video data having the HDR opto-electrical transfer characteristic) (see  FIG. 11 ). 
     In the switch  106 C, transmission video data A (SDR transmission video data) obtained by the SDR opto-electrical transfer unit  104 , transmission video data B (HDR transmission video data) obtained by the HDR opto-electrical transfer unit  103 , or transmission video data C(HDR transmission video data) obtained by the dynamic range conversion unit  105  are selectively extracted under the control of the control unit  101 . The thus extracted transmission video data are converted f rom the RGB domain to the YCbCr (luminance/chrominance) domain by the RGB/YCbCr conversion unit  107 . 
     The transmission video data V 1  resulting from the conversion to YCbCr domain are supplied to the video encoder  108 . In the video encoder  108 , encoding in MPEG4-AVC or HEVC, for example is performed on the transmission video data V 1 , encoded video data are obtained, and a video stream VS containing the encoded video data is generated. In this process, in the video encoder  108 , meta-information, such as information indicating whether the video stream is an SDR stream or an HDR stream and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 , is inserted into a region of VUI of an SPS NAL unit of an access unit (AU). 
     The video stream VS obtained by the video encoder  108  is supplied to the container encoder  109 . In the container encoder  109 , a transport stream (an MPEG-2 transport stream or an MMT stream) containing the video stream VS generated by the video encoder  108  is generated. The transport stream is transmitted by transmission unit  110  on a broadcast wave or in a packet over a network to the service receiver  200 . 
     For this process, in the container encoder  109 , a descriptor (the dynamic range conversion descriptor (see  FIG. 17 ) or the descriptor of HDR descriptor_type3 (see  FIG. 6 )) describing identification information representing the transmission video data A, the transmission video data B, or the transmission video data C is inserted into the transport stream that is a container. In this case, in the container encoder  109 , the identification information is inserted so that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing. 
     “Example Configuration of Service Receiver” 
       FIG. 21  illustrates an example configuration of a service receiver  200 A, which corresponds to the service receiver  200  illustrated in  FIG. 1 . In the service receiver  200 A, the display performance of a display monitor is in SDR. The service receiver  200 A includes a control unit  201 , a reception unit  202 , a container decoder  203 , a video decoder  204 , a YCbCr/RGB conversion unit  205 , an HDR/SDR conversion unit  206 , and an SDR electro-optical transfer unit  207 . 
     The control unit  201  includes a central processing unit (CPU), and controls operation of the respective units of the service receiver  200 A on the basis of control programs. The reception unit  202  receives a transport stream (an MPEG-2 transport stream or an MMT stream) as a container transmitted from the service transmission system  100 A (see  FIG. 2 ), the service transmission system  100 B (see  FIG. 10 ), or the service transmission system  100 C (see  FIG. 16 ) on a broadcast wave or in a packet over a network. The container decoder  203  extracts a video stream VS from the transport stream. 
     In addition, the container decoder  203  extracts various kinds of information inserted in the transport stream, and sends the extracted information to the control unit  201 . The information also includes the descriptor of HDR descriptor_type1 (see  FIG. 5 ), the descriptor of HDR descriptor_type2 (see  FIG. 13 ), the descriptor of HDR descriptor_type3 (see  FIG. 6 ) or the dynamic range conversion descriptor (see  FIG. 17 ) described above describing the identification information of the transmission video data. 
     The control unit  201  recognizes that the transmission video data included in the video stream Vs are the transmission video data A (SDR transmission video data), the transmission video data B (HDR transmission video data), or the transmission video data C (HDR transmission video data) on the basis of the description of the descriptor. As described above, the identification information of the transmission video data is inserted in the transport stream such that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is predetermined amount of time or longer before the switching timing. 
     The control unit  201  is thus capable of recognizing that the kind of transmission video data will be switched and further recognizing the kind of transmission video data resulting from the switching, from the timing that is the predetermined amount of time or longer before the switching timing of the transmission video data. The control unit  201  is therefore capable of preparing for control of the respective units associated with the switching of the kind of transmission video data, and smoothly and appropriately performing a control process for obtaining image data for display from the transmission video data even when the kind of transmission video data is switched. 
     As described above, the transmission video data A are SDR transmission video data obtained by performing SDR opto-electrical conversion on SDR video data Vs. In addition, the transmission video data B are HDR transmission video data obtained by performing HDR opto-electrical conversion on HDR video data Vh. In addition, the transmission video data C are HDR transmission video data obtained by performing SDR opto-electrical conversion on SDR video data Vs and further performing dynamic range conversion on the resulting SDR transmission video data. 
     The video decoder  204  decodes the video stream VS extracted by the container decoder  203  to obtain the transmission video data V 1 . The video decoder  204  also extracts information, such as a parameter set and an SEI message, inserted in each access unit from the video stream VS, and sends the extracted information to the control unit  201 . The information also includes meta-information inserted into a region of VUI of an SPS NAL unit of an access unit, such as information indicating whether the video stream is an SDR stream or an HDR stream, and information indicating an electro-optical transfer characteristic associated with the opto-electrical transfer characteristic of the transmission video data V 1 . 
     The YCbCr/RGB conversion unit  205  converts the transmission video data V 1  obtained by the video decoder  204  from the YCbCr (luminance/chrominance) domain to the RGB domain. Note that the color space domain is not limited to the RGB domain, and that the luminance/chrominance domain is not limited to the YCbCr. 
     The HDR/SDR conversion unit  206  performs dynamic range conversion on the HDR transmission video data under the control of the control unit  201  to obtain SDR transmission video data. The HDR/SDR conversion unit  206  functions in a case where the transmission video data V 1  are the transmission video data B or the transmission video data C, which are HDR transmission video data, or outputs the input without any change in a case where the transmission video data V 1  are the transmission video data A, which are SDR transmission video data. 
     Details of the dynamic range conversion in a case where the transmission video data V 1  are the transmission video data C (HDR transmission video data) will be explained with reference to  FIG. 22 . The vertical axis represents an output luminance level, which is associated with the horizontal axis of  FIG. 11 . In addition, the horizontal axis represents a transmitted code value, which is associated with the vertical axis of  FIG. 11 . A solid curve a is an SDR EOTF curve representing the SDR electro-optical transfer characteristic. The SDR EOTF curve is associated with the SDR OETF curve shown as the solid curve a in  FIG. 11 . A solid curve b is an HDR EOTF curve representing the HDR electro-optical transfer characteristic. The HDR EOTF curve is associated with the HDR OETF curve shown as the solid curve b in  FIG. 11 . Note that  FIG. 23  shows an example of a case in which the branch level B is 0, which is associated with the example of  FIG. 12 . 
     The dynamic range conversion of the HDR/SDR conversion unit  206  is conversion reverse to that of the dynamic range conversion unit  105  in  FIG. 10 . Specifically, the dynamic range conversion is performed so that data at the branch level B or higher but the reference level G or lower among the HDR transmission video data are converted to have a value equal to that of data converted with the SDR opto-electrical transfer characteristic. In this case, the reference level G is made to be equal to the relative maximum level M that is the maximum SDR level. Note that input data not higher than the branch level B are output as output data without any change. 
     Note that the conversion information is in a form of a conversion table or a conversion coefficient provided by the control unit  201 , for example. In a case where the conversion information is in a form of a conversion table, the HDR/SDR conversion unit  206  refers to the conversion table to perform the conversion. In a case where the conversion information is in a form of a conversion coefficient, the HDR/SDR conversion unit  206  performs the conversion by computation using the conversion coefficient. For example, when the conversion coefficient is represented by C, conversion is performed on the input data at the branch level B or higher but the reference level G or lower by the following expression (3). 
       Output data=branch level  B +(input data−branch level  B )*1/ C    (3)
 
     Next, details of the dynamic range conversion in a case where the transmission video data V 1  are the transmission video data B (HDR transmission video data) will be explained with reference to  FIG. 24 . In this case, in the HDR/SDR conversion unit  206 , an input level to the HDR EOTF curve is converted to an input level to the SDR EOTF curve. In  FIG. 24 , parts corresponding to those in  FIG. 22  are designated by the same reference numerals. Note that P 1 ′ represents an output luminance level associated with a predetermined level H lower than the reference level G. 
     In this case, for input data up to a predetermined level H lower than the reference level G, the dynamic range conversion in the HDR/SDR conversion unit  207  is conversion similar to that in the case where the transmission video data V 1  are the transmission video data C (HDR transmission video data) described above. Then, for input data from the level H to the level M, level conversion based on tone mapping characteristics TM shown by a dashed-dotted line is performed and output data are obtained. In this case, the level H is converted to a level H′, the reference level G is converted to a level G′, and the level M remains unchanged, for example. 
     The level conversion based on the tone mapping characteristics TM for input data from the level H to the level M in this manner allows reduction in image quality degradation due to level saturation for input data in the range from the reference level G to the relative maximum level M. 
     The description refers back to  FIG. 21 , in which the SDR electro-optical transfer unit  207  applies the SDR electro-optical transfer characteristic to the SDR transmission video data output from the HDR/SDR conversion unit  206  to obtain video data Vsd for display to display an SDR image. 
     Operation of the service receiver  200 A illustrated in  FIG. 21  will be briefly explained. In the reception unit  202 , a transport stream (an MPEG-2 transport stream or an MMT stream) transmitted from the service transmission system  100 A, the service transmission system  100 B, or the service transmission system  100 C on a broadcast wave or in a packet over a network is received. The transport stream is supplied to the container decoder  203 . In the container decoder  203 , a video stream VS is extracted from the transport stream. 
     In addition, in the container decoder  203 , various kinds of information inserted in the transport stream that is a container is extracted and sent to the control unit  201 . The information also includes the descriptor of HDR descriptor_type1 (see  FIG. 5 ), the descriptor of HDR descriptor_type2 (see  FIG. 13 ), the descriptor of HDR descriptor_type3 (see  FIG. 6 ) or the dynamic range conversion descriptor (see  FIG. 17 ) described above. 
     In the control unit  201 , it is recognized whether the transmission video data included in the video stream Vs are the transmission video data A (SDR transmission video data), the transmission video data B (HDR transmission video data), or the transmission video data C (HDR transmission video data) on the basis of the description of the descriptor. 
     The video stream VS extracted by the container decoder  203  is supplied to the video decoder  204 . In the video decoder  204 , the video stream VS is decoded, and the transmission video data V 1  are obtained. In addition, in the video decoder  204 , information, such as a parameter set and an SEI message, inserted in each access unit is extracted f rom the video stream VS and sent to the control unit  201 . 
     The transmission video data V 1  obtained by the video decoder  204  is converted from the YCbCr (luminance/chrominance) domain to the RGB domain by the YCbCr/RGB conversion unit  205 . The transmission video data V 1  resulting from the conversion to the RGB domain are supplied to the HDR/SDR conversion unit  206 . 
     In the HDR/SDR conversion unit  206 , in a case where the transmission video data V 1  are the transmission video data B or the transmission video data C, which are HDR transmission video data, the dynamic range conversion is performed on the HDR transmission video data, and SDR transmission video data are obtained (see  FIGS. 22 to 24 ). Note that, in a case where the transmission video data V 1  are the transmission video data A, which are SDR transmission video data, the input is output without any change. 
     The SDR transmission video data obtained by the HDR/SDR conversion unit  206  are supplied to the SDR electro-optical transfer unit  207 . In the SDR electro-optical transfer unit  207 , the SDR electro-optical transfer characteristic is applied to the SDR transmission video data, and video data Vsd for display of an SDR image are obtained. The video data Vsd for display is subjected to a display mapping process depending on the display capability of a display monitor where necessary, and then supplied to the display monitor for display of the SDR image. 
       FIG. 25  illustrates an example configuration of a service receiver  200 B, which corresponds to the service receiver  200  illustrated in  FIG. 1 . In  FIG. 25 , parts corresponding to those in  FIG. 21  are designated by the same reference numerals, and detailed description thereof will not be repeated as appropriate. In the service receiver  200 B, the display performance of the display monitor is in HDR. The service receiver  200 B includes a control unit  201 , a reception unit  202 , a container decoder  203 , a video decoder  204 , a YCbCr/RGB conversion unit  205 , an SDR/HDR conversion unit  208 , and an HDR electro-optical transfer unit  209 . 
     The control unit  201  includes a CPU, and controls operation of the respective units of the service receiver  200 B on the basis of control programs. The reception unit  202  receives a transport stream (an MPEG-2 transport stream or an MMT stream) as a container transmitted from the service transmission system  100 A (see  FIG. 2 ), the service transmission system  100 B (see  FIG. 10 ), or the service transmission system  100 C (see  FIG. 16 ) on a broadcast wave or in a packet over a network. The container decoder  203  extracts a video stream VS from the transport stream. 
     In addition, the container decoder  203  extracts various kinds of information inserted in the transport stream, and sends the extracted information to the control unit  201 . The information also includes the descriptor of HDR descriptor_type1 (see  FIG. 5 ), the descriptor of HDR descriptor_type2 (see  FIG. 13 ), the descriptor of HDR descriptor_type3 (see  FIG. 6 ) or the dynamic range conversion descriptor (see  FIG. 17 ) described above. 
     The control unit  201  recognizes whether the transmission video data included in the video stream Vs are the transmission video data A (SDR transmission video data), the transmission video data B (HDR transmission video data), or the transmission video data C (HDR transmission video data) on the basis of the description of the descriptor. In this case, the control unit  201  is capable of recognizing that the kind of transmission video data will be switched and further recognizing the kind of transmission video data resulting from the switching, from the timing that is a predetermined amount of time or longer before the switching timing of the transmission video data. 
     The video decoder  204  decodes the video stream VS extracted by the container decoder  203  to obtain the transmission video data V 1 . The YCbCr/RGB conversion unit  205  converts the transmission video data V 1  obtained by the video decoder  204  from the YCbCr (luminance/chrominance) domain to the RGB domain. 
     The SDR/HDR conversion unit  208  performs dynamic range conversion on the SDR transmission video data under the control of the control unit  201  to obtain HDR transmission video data. The SDR/HDR conversion unit  206  functions in a case where the transmission video data V 1  are the transmission video data A, which are SDR transmission video data, or outputs the input without any change in a case where the transmission video data V 1  are the transmission video data B or the transmission video data C, which are HDR transmission video data. 
     Details of the dynamic range conversion in a case where the transmission video data V 1  are the transmission video data A (SDR transmission video data) will be explained with reference to  FIG. 26 . In this case, in the SDR/HDR conversion unit  208 , an input level to the SDR EOTF curve is converted to an input level to the HDR EOTF curve. In  FIG. 26 , parts corresponding to those in  FIG. 22  are designated by the same reference numerals. 
     The dynamic range conversion of the SDR/HDR conversion unit  208  is conversion similar to that of the dynamic range conversion unit  105  in  FIGS. 10 and 16 . Specifically, the dynamic range conversion is performed so that data at the branch level B or higher but the relative maximum level M, which is the maximum SDR level, or lower among the SDR transmission video data are converted to have a value equal to that of data converted with the HDR opto-electrical transfer characteristic. In this case, the relative maximum level M is made to be equal to the reference level G. Note that input data not higher than the branch level B are output as output data without any change. 
     The description refers back to  FIG. 25 , in which the HDR opto-electrical transfer unit  209  applies the HDR electro-optical transfer characteristic to the HDR transmission video data output from the HDR/SDR conversion unit  208  to obtain video data Vhd for display to display an HDR image. 
     Operation of the service receiver  200 B illustrated in  FIG. 25  will be briefly explained. In the reception unit  202 , a transport stream (an MPEG-2 transport stream or an MMT stream) transmitted from the service transmission system  100 A, the service transmission system  100 B, or the service transmission system  100 C on a broadcast wave or in a packet over a network is received. The transport stream is supplied to the container decoder  203 . In the container decoder  203 , a video stream VS is extracted from the transport stream. 
     In addition, in the container decoder  203 , various kinds of information inserted in the transport stream that is a container is extracted and sent to the control unit  201 . The information also includes the descriptor of HDR descriptor_type1 (see  FIG. 5 ), the descriptor of HDR descriptor_type2 (see  FIG. 13 ), the descriptor of HDR descriptor_type3 (see  FIG. 6 ) or the dynamic range conversion descriptor (see  FIG. 17 ) described above. 
     In the control unit  201 , it is recognized whether the transmission video data included in the video stream Vs are the transmission video data A (SDR transmission video data), the transmission video data  8  (HDR transmission video data), or the transmission video data C (HDR transmission video data) on the basis of the description of the descriptor. 
     The video stream VS extracted by the container decoder  203  is supplied to the video decoder  204 . In the video decoder  204 , the video stream VS is decoded, and the transmission video data V 1  are obtained. In addition, in the video decoder  204 , information, such as a parameter set and an SEI message, inserted in each access unit is extracted from the video stream VS and sent to the control unit  201 . 
     The transmission video data V 1  obtained by the video decoder  204  is converted from the YCbCr (luminance/chrominance) domain to the RGB domain by the YCbCr/RGB conversion unit  205 . The transmission video data V 1  resulting from the conversion to the RGB domain are supplied to the SDR/HDR conversion unit  206 . 
     In the SDR/HDR conversion unit  208 , in a case where the transmission video data V 1  are the transmission video data A, which are SDR transmission video data, the dynamic range conversion is performed on the SDR transmission video data, and HDR transmission video data are obtained (see  FIG. 26 ). Note that, in a case where the transmission video data V 1  are the transmission video data B or the transmission video data C, which are HDR transmission video data, the input is output without any change. 
     The HDR transmission video data obtained by the SDR/HDR conversion unit  208  are supplied to the HDR electro-optical transfer unit  209 . In the HDR electro-optical transfer unit  209 , the HDR electro-optical transfer characteristic is applied to the HDR transmission video data, and video data Vhd for display of an HDR image are obtained. The video data Vhd for display is subjected to a display mapping process depending on the display capability of a display monitor where necessary, and then supplied to the display monitor for display of the HDR image. 
     As described above, in the transmission/reception system  10  illustrated in  FIG. 1 , the service transmission system  100  inserts, into a transport stream that is a container, identification information representing the kind of transmission video data contained in a video stream Vs included in the transport stream, such that the identification information indicates the kind of transmission video data resulting from the switching, from a timing that is a predetermined amount of time or longer before the switching timing. 
     This allows the service receiver  200  to recognize that the kind of transmission video data will be switched and further recognize the kind of transmission video data resulting from the switching, from the timing that is a predetermined amount of time or longer before the switching timing of the transmission video data. This therefore enables the service receiver  200  to prepare for control of the respective units associated with the switching of the kind of transmission video data, and smoothly and appropriately perform a control process for obtaining image data for display from the transmission video data even when the kind of transmission video data is switched. 
     &lt;2. Modifications&gt; 
     Note that, while the transmission/reception system  10  constituted by the service transmission system  100  and the service receiver  200  has been presented in the embodiment described above, the configuration of a transmission/reception system to which the present technology is applicable is not limited to the above. For example, the service receiver  200  may have a configuration including a set-top box (STB) and a monitor connected via a digital interface such as a high-definition multimedia interface (HDMI). Note that “HDMI” is a registered trademark. 
     Furthermore, an example in which information such as the reference level and the branch level is also inserted with the identification information of transmission image data into a transport stream that is a container before transmission has been presented in the embodiment described above. In a case where the value of the information such as the reference level and the branch level is uniquely obtained through reference to the opto-electrical transfer characteristic, however, the identification information of the opto-electrical transfer characteristic can be used as a substitute for the level value without transmission of the level value itself. In this case, the identification information for an opto-electrical transfer characteristic may be supplied by a container or by a video stream. 
     Furthermore, the present technology can also have the following configurations. 
     (1) A transmission device including: 
     an encoding unit configured to encode transmission video data obtained by switching between a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics to obtain a video stream; 
     a transmission unit configured to transmit a container in a predetermined format containing the video stream; and 
     an information insertion unit configured to insert, into the container, identification information representing a kind of a transmission video data in the video stream contained in the container, such that the identification information indicates the kind of transmission video data resulting from switching, from a timing a predetermined amount of time or longer before a timing of the switching. 
     (2) The transmission device described in (1), in which the plurality of kinds of transmission video data include: 
     first transmission video data having a standard dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data; and 
     second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data. 
     (3) The transmission device described in (1), in which the plurality of kinds of transmission video data include: 
     first transmission video data having a high dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data; and 
     second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with a standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data and performing dynamic range conversion on the video data resulting from the opto-electrical conversion, the dynamic range conversion being based on conversion information for converting a value of data converted with the standard dynamic range opto-electrical transfer characteristic into a value of data converted with the high dynamic range opto-electrical transfer characteristic. 
     (4) The transmission device described in (1), in which the plurality of kinds of transmission video data include: 
     first transmission video data having a standard dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data; 
     second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data; and 
     third transmission video data having a high dynamic range opto-electrical transfer characteristic, the third transmission video data being obtained by performing opto-electrical conversion with a standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data and performing dynamic range conversion on the video data resulting from the opto-electrical conversion, the dynamic range conversion being based on conversion information for converting a value of data converted with the standard dynamic range opto-electrical transfer characteristic into a value of data converted with the high dynamic range opto-electrical transfer characteristic. 
     (5) The transmission device described in any one of (1) to (4), in which the information insertion unit further inserts, into the container, information on a reference level being a reference luminance level or information on branch level being a luminance level at which a trajectory followed by curves of a standard dynamic range opto-electrical transfer characteristic and a high dynamic range opto-electrical transfer characteristic bifurcates. 
     (6) The transmission device described in any of (1) to (5), in which the container is an MPEG-2 transport stream or an MMT stream. 
     (7) A transmission method including: 
     an encoding step of encoding transmission video data obtained by switching between a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics to obtain a video stream; 
     a transmitting step of transmitting, by a transmission unit, a container in a predetermined format containing the video stream; and 
     an information inserting step of inserting, into the container, identification information representing a kind of a transmission video data in the video stream contained in the container, such that the identification information indicates the kind of transmission video data resulting from switching, from a timing a predetermined amount of time or longer before a timing of the switching. 
     (8) A reception device including: a reception unit configured to receive a container in a predetermined format containing a video stream obtained by encoding transmission video data, in which 
     the transmission video data is an output of switching between a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics, 
     in the container identification information representing a kind of transmission video data of the video stream contained by the container is inserted such that the identification information indicates the kind of transmission video data resulting from switching, from a timing a predetermined amount of time or longer before a timing of the switching, and 
     the reception device further includes: 
     a decoding unit configured to decode the video stream to obtain transmission video data; and 
     a processing unit configured to perform an electro-optical conversion process based on the identification information and display performance on the transmission video data obtained by the decoding unit, to obtain image data for display. 
     (9) The reception device described in (8), in which 
     the plurality of kinds of transmission video data include: first transmission video data having a standard dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data; and second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data, 
     when the display performance is in a high dynamic range and: 
     in a case where the transmission video data are the first transmission video data, the processing unit performs dynamic range conversion on the transmission video data and then performs an electro-optical conversion process with the high dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display, or in a case where the transmission video data are the second transmission video data, the processing unit performs electro-optical conversion with the high dynamic range electro-optical transfer characteristic on the transmission video data to obtain the image data for display, and 
     when the display performance is in a standard dynamic range and: 
     in a case where the transmission video data are the first transmission video data, the processing unit performs electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the transmission video data to obtain the image data for display, or in a case where the transmission video data are the second transmission video data, the processing unit performs dynamic range conversion on the transmission video data and then performs electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display. 
     (10) The reception device described in (8), in which 
     the plurality of kinds of transmission video data include: first transmission video data having a high dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data; and second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with a standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data and performing dynamic range conversion on the video data resulting from the opto-electrical conversion, the dynamic range conversion being based on conversion information for converting a value of data converted with the standard dynamic range opto-electrical transfer characteristic into a value of data converted with the high dynamic range opto-electrical transfer characteristic, 
     when the display performance is in a high dynamic range and: 
     in a case where the transmission video data are either of the first transmission video data and the second transmission video data, the processing unit performs electro-optical conversion with the high dynamic range electro-optical transfer characteristic on the transmission video data to obtain the image data for display, and 
     when the display performance is in a standard dynamic range and: 
     in a case where the transmission video data are the first transmission video data, the processing unit performs dynamic range conversion with a first conversion characteristic on the transmission video data and then performs electro-optical conversion with the standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display, or in a case where the transmission video data are the second transmission video data, the processing unit performs dynamic range conversion with a second conversion characteristic on the transmission video data and then performs electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display. 
     (11) The reception device described in (8), in which 
     the plurality of kinds of transmission video data include: first transmission video data having a standard dynamic range opto-electrical transfer characteristic, the first transmission video data being obtained by performing opto-electrical conversion with the standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data; second transmission video data having a high dynamic range opto-electrical transfer characteristic, the second transmission video data being obtained by performing opto-electrical conversion with the high dynamic range opto-electrical transfer characteristic on high dynamic range video data; and third transmission video data having a high dynamic range opto-electrical transfer characteristic, the third transmission video data being obtained by performing opto-electrical conversion with a standard dynamic range opto-electrical transfer characteristic on standard dynamic range video data and performing dynamic range conversion on the video data resulting from the opto-electrical conversion, the dynamic range conversion being based on conversion information for converting a value of data converted with the standard dynamic range opto-electrical transfer characteristic into a value of data converted with the high dynamic range opto-electrical transfer characteristic, 
     when the display performance is in a high dynamic range and: 
     in a case where the transmission video data are the first transmission video data, the processing unit performs dynamic range conversion on the transmission video data and then performs electro-optical conversion with a high dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display, or in a case where the transmission video data are the second transmission video data or the third transmission video data, the processing unit performs electro-optical conversion with a high dynamic range electro-optical transfer characteristic on the transmission video da a to obtain the image data for display, and 
     when the display performance is in a standard dynamic range and: 
     in a case where the transmission video data are the first transmission video data, the processing unit performs electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the transmission video data to obtain the image data for display, in a case where the transmission video data are the second transmission video data, the processing unit performs dynamic range conversion with a first conversion characteristic on the transmission video data and then performs electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display, or in a case where the transmission video data are the third transmission video data, the processing unit performs dynamic range conversion with a second conversion characteristic on the transmission video data and then performs electro-optical conversion with a standard dynamic range electro-optical transfer characteristic on the resulting transmission video data to obtain the image data for display. 
     (12) A reception method including: 
     a receiving step of receiving, by a reception unit, a container in a predetermined format containing a video stream obtained by encoding transmission video data, in which 
     the transmission video data being an output of switching between a plurality of kinds of transmission video data having predetermined opto-electrical transfer characteristics, 
     in the container, identification information representing a kind of transmission video data of the video stream contained by the container is inserted such that the identification information indicates the kind of transmission video data resulting from switching, from a timing a predetermined amount of time or longer before a timing of the switching, and 
     the reception method further includes: 
     a decoding step of decoding the video stream to obtain transmission video data; and 
     a processing step of performing an electro-optical conversion process based on the identification information and display performance on the transmission video data obtained by the decoding step, to obtain image data for display. 
     A Major feature of the present technology is that identification information representing a kind of transmission video data included in a video stream contained in a container is inserted into the container such that the identification information indicates the kind of transmission video data resulting from switching, from a timing that is a predetermined amount of time or longer before the switching timing, which allows a receiver side to smoothly and appropriately perform a process for obtaining image data for display from the transmission video data even when the kind of transmission video data is switched (see  FIGS. 4 and 8 ). 
     REFERENCE SIGNS LIST 
     
         
           10  Transmission/reception system 
           100 ,  100 A,  100 B,  100 C Service transmission system 
           101  Control unit 
           103  HDR opto-electrical transfer unit 
           104  SDR opto-electrical transfer unit 
           105  Dynamic range conversion unit 
           106 A,  106 B,  106 C Switch 
           107  RGB/YCbCr conversion unit 
           108  Video encoder 
           109  Container encoder 
           110  Transmission unit 
           200 ,  200 A,  200 B Service receiver 
           201  Control unit 
           202  Reception unit 
           203  Container decoder 
           204  Video decoder 
           205  YCbCr/RGB conversion unit 
           206  HDR/SDR conversion unit 
           207  SDR electro-optical transfer unit 
           208  SDR/HDR conversion unit 
           209  HDR electro-optical transfer unit