VIDEO TRANSMISSION METHOD, VIDEO RECEPTION METHOD, VIDEO TRANSMISSION APPARATUS, AND VIDEO RECEPTION APPARATUS

Abstract

A video transmission method according to the present description includes: generating a transmission signal that includes, in a time series, first video data having a first dynamic range of luminance and second video data having a second dynamic range of luminance wider than the first dynamic range of luminance; and transmitting the generated transmission signal. In generating the transmission signal, a signal level corresponding to a luminance value is limited to a lower value than a predetermined limit value, within a transition period provided for switching from one of the first video data and the second video data to the other.

Description

High dynamic range (HDR) has been gaining attention as a scheme that covers a wider luminance range with an increased peak luminance value in order to represent bright light, such as light reflected by a mirror, which cannot be represented using current TV signals. HDR achieves brightness closer to real-world brightness while maintaining the gradation of the dark areas of the existing video. Specifically, the scheme that covers the luminance range supported by existing TV signals is called standard dynamic range (SDR) and has a peak luminance value of 100 nits. In contrast, HDR is expected to have an increased peak luminance value of at least 1000 nits. List of Bibliographic References Bibliography that is not Patent NPL 1: ARIB STANDARD ARIB STD-B67 Version 1.0 July 3, 2015 NPL 2: BBC Research & Development White Paper WHP 283, July 2014 Brief Description of the Invention With regard to the transmission or reception of video signals that support a plurality of luminance dynamic ranges as described above, there is a demand for easier switching of the luminance dynamic range by a video receiving apparatus. In view of the above, the present description provides a video transmission method, a video reception method, a video transmission apparatus, or a video reception apparatus that makes it possible for a video reception apparatus to more easily switch a dynamic range of luminance. A video transmission method according to one aspect of the present description includes: generating a transmission signal that includes, in a time series, first video data having a first dynamic range of luminance and second video data having a second dynamic range of luminance wider than the first dynamic range of luminance; and transmitting the generated transmission signal. In generating the transmission signal, a signal level corresponding to a luminance value is limited to a value lower than a predetermined limit value, in a transition period provided to switch from one of the first video data and the second video data to the other. A video reception method according to one aspect of the present description is a video reception method implemented by a video receiving apparatus that includes a display. The video reception method includes receiving a reception signal that includes, in a time series, first video data having a first dynamic range of luminance and second video data having a second dynamic range of luminance that is wider than the first dynamic range of luminance. In the reception signal, a signal level corresponding to a luminance value is limited to a value lower than a predetermined limit value, during a transition period provided to switch from one of the first video data and the second video data to the other.The receiving signal includes initial information to notify, immediately after the start of the transition period, the switching of a dynamic luminance range. The video receiving method also includes switching the dynamic luminance range of the display for a permitted switching time that begins when the initial information is received; the permitted switching time is the length of time allowed to switch the dynamic luminance range. It should be noted that these general or specific aspects can be implemented by a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a compact disc read-only memory (CD-ROM), or by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium. The present description may provide a method of video transmission, a method of video reception, a video transmission apparatus, or a video reception apparatus that makes it possible for a video reception apparatus to more easily switch a dynamic range of luminance. Brief Description of the Figures FIGURE 1 is a block diagram of a video receiving apparatus according to Mode 1. FIGURE 2 is a flowchart of the processing performed by a ci cbnn / ι ζπζ / ε / υιλι screen controller according to Mode 1. FIGURE 3 is a flowchart of a video reception processing according to Mode 1. FIGURE 4 illustrates an operation performed when there is a change in the transfer characteristics according to Mode 1. FIGURE 5 illustrates an operation performed when there is a change in the transfer characteristics according to Mode 1. FIGURE 6 is a block diagram of a video transmission apparatus according to Mode 1. FIGURE 7 illustrates a flowchart of a video transmission processing according to Mode 1. FIGURE 8 illustrates an abnormal operation performed when there is a change in the transfer characteristics according to Mode 2. FIGURE 9 is a block diagram of a video receiving apparatus according to Mode 2. FIGURE 10 is a flowchart of the processing performed by a display controller according to Mode 2. FIGURE 11 illustrates an example of a timestamp descriptor according to Modality 3. FIGURE 12 illustrates an example of an extended timestamp ci cbnn / ι ζπζ / ε / υιλι descriptor according to Modality 3. FIGURE 13 illustrates an example of a video component descriptor according to Modality 3. FIGURE 14 illustrates a flowchart of the processing performed by a display controller according to Mode 3. FIGURE 15 illustrates a flowchart of the video reception processing according to Mode 3. FIGURE 16 illustrates an example of a curve showing a relationship between the electrical signal level and HDR luminance and a curve showing a relationship between the electrical signal level and SDR luminance according to Mode 4. FIGURE 17 illustrates an operation performed to switch from SDR to HDR according to Mode 4. FIGURE 18 illustrates an operation performed to switch from HDR to SDR according to Mode 4. FIGURE 19 is a block diagram of a video transmission apparatus according to Mode 4. FIGURE 20 illustrates a flowchart of video transmission processing according to Mode 4. FIGURE 21 is a block diagram of a ci cbnn / ι ζπζ / ε / υιλι video receiving apparatus according to Mode 4. FIGURE 22 illustrates a flowchart of the video reception processing according to Mode 4. Detailed Description of the Invention Basis that Forms the Fundamental Knowledge of the Present Description According to, for example, a video coding standard known as ITU-T H.265|ISO / IEC 23008-2 HEVC, the opto-electrical transfer function (OETF) or electro-optical transfer function (EOTF) of a video signal is reported using a syntax known as transfer characteristics in video usability information (VUI) included in a sequence parameter set (SPS). The use of transfer characteristics in the SPS makes it possible to report the switching of transfer characteristics (transfer function) in frame accuracy. A video receiving device determines a method for controlling a video display based on these transfer characteristics. According to the MPEG-2 Transport Stream (TS) standard, which is used to transmit a video and audio signal in a multiplexed manner, as in the case of a TV broadcaster, etc., there is a known method of including, in a Program-Specific Information Descriptor (PSI), a parameter included in the aforementioned SPS and information related to that parameter, and transmitting information related to the operation of the video receiving apparatus at a higher layer. By also using the PSI descriptor for transfer characteristics, the video receiving apparatus can more easily determine a method for controlling video display. Since the PSI is generally inserted into a multiplexed stream on a constant cycle, the PSI is not synchronized with frames of a video signal.It should be noted that according to the MPEG-H MPEG Media Transport (MMT) standard, a structure similar to PSI is defined as MMT-SI. The transfer characteristics are defined by, for example, ITU-R BT.2020 (hereinafter BT.2020), ARIB STD-B67 (hereinafter STD-B67), and SMPTE ST2084 (hereinafter ST2084). STD-B67 and ST2084 can handle a video signal with a luminance ten to one hundred times higher than conventional BT.2020, known as high dynamic range (HDR). In contrast to HDR, the dynamic range of conventional BT.2020, etc., is called standard dynamic range (SDR). The HDR-compatible TV station may include both HDR and SDR programs and commercials. Therefore, the video receiver needs to operate while switching the on-screen control, depending on whether the program / commercial is in HDR or SDR. A video transmission method according to one aspect of the present description includes: generating a transmission signal that includes, in a time series, first video data having a first dynamic range of luminance and second video data having a second dynamic range of luminance wider than the first dynamic range of luminance; and transmitting the generated transmission signal. In generating the transmission signal, a signal level corresponding to a luminance value is limited to a value lower than a predetermined threshold value, over a transition period provided to switch from one of the first video data and the second video data to the other. This limits the signal level of the video data to a lower value than the threshold value during the transition period provided to switch to video data that has a different luminance dynamic range. ci cbnn / ι ζπζ / ε / υιλι In this way, the video receiver does not need to change the dynamic range of the display's luminance frame by frame, for example, and only needs to change the dynamic range of the display's luminance during the transition period. This makes switching the dynamic range of luminance by the video receiver much easier. For example, in the generation of the transmission signal, the signal level corresponding to the luminance value can be limited to the lower value than the limit value in a first transition period provided to switch from the first video data to the second video data. For example, in generating the transmission signal, the signal level corresponding to the luminance value does not need to be limited to the lowest value, which is the limit value, in a second transition period provided to switch from the second video data to the first video data. For example, the transmission signal may include initial information to notify, in a first period immediately after the start of the transition period, the switching of a dynamic luminance range. For example, the first period can be a period of time from immediately after the start of the transition period ci cbnn / ι ζπζ / ε / υιλι until a time preceding a switching time by an allowable switching time, the switching time is a time in which one of the first video data and the second video data are switched to the other, the allowable switching time is a length of time allowed for the switching of the luminance dynamic range by a video receiving apparatus that receives the transmission signal. For example, in generating the transmission signal, a video signal can be generated by encoding the first video data and the second video data, and the transmission signal that includes the first information can be generated by multiplexing the generated video signal and an audio signal. For example, the transmission signal may include secondary information indicating the transition period. A video reception method according to one aspect of the present description is a video reception method implemented by a video receiving apparatus that includes a display. The video reception method includes: receiving a reception signal that includes, in a time series, first video data having a first dynamic range of luminance and second video data having a second dynamic range of luminance wider than the first dynamic range of imminence. In the reception signal, a signal level corresponding to a luminance value is limited to a value lower than a predetermined limit value, during a transition period provided to switch from one of the first video data and the second video data to the other.The reception signal includes initial information to notify, immediately after the start of the transition period, the switching of a dynamic luminance range. The video reception method further includes: switching the dynamic luminance range of the display for a permitted switching time that begins when the initial information is received; the permitted switching time is the length of time allowed to switch the dynamic luminance range. This limits the video signal level to a lower value than the threshold during the transition period required to switch to video data with a different luminance dynamic range. This way, the video receiver doesn't need to change the display's luminance dynamic range frame by frame, for example, and only needs to change the display's luminance dynamic range during the transition period. As a result, the video receiver can more easily switch between luminance dynamic ranges. For example, the first period can be a period of time from immediately after the start of the transition period until a time preceding a switching time by the time allowed for switching; the switching time is a time in which one of the first video data and the second video data are switched to the other. For example, the video reception method may also include: obtaining a video signal and the first data by demultiplexing the multiplexed reception signal of the video signal and an audio signal; and obtaining the first video data and the second video data by decoding the obtained video signal. For example, the receiving signal may include secondary information indicating the transition period. A video transmission apparatus according to one aspect of the present description includes: a generator that produces a transmission signal comprising, in a time series, first video data having a first dynamic range of luminance and second video data having a second dynamic range of luminance wider than the first dynamic range of luminance; and a transmitter that emits the generated transmission signal. The generator limits a signal level corresponding to a luminance value aci cbnn / ι ζπζ / ε / υιλι to a value lower than a predetermined limit value, over a transition period provided to switch from one of the first video data and the second video data to the other. This limits the video signal level to a lower value than the threshold during the transition period, allowing the video data to switch to a different dynamic range. This means the video receiver doesn't need to change the display's dynamic range frame by frame, for example, but only during the transition period. This simplifies dynamic range switching for the video receiver. A video receiving apparatus according to one aspect of the present description is a video receiving apparatus that includes a display. The video receiving apparatus includes a receiver that accepts a receiving signal comprising, in a time series, first video data having a first dynamic range of luminance and second video data having a second dynamic range of luminance wider than the first dynamic range of luminance. In the receiving signal, a signal level corresponding to a luminance value is limited to a value lower than a predetermined limit, during a transition period provided to switch from one of the first video data and the second video data to the other. The receiving signal includes first information to notify, in a first period immediately following the start of the transition period, of the switching of a dynamic range of luminance.The video receiving apparatus further includes: a display controller that switches the dynamic range of the display's luminance for a switching allowance time which begins when the first information is obtained, and the switching allowance time is a length of time allowed to switch the dynamic range of luminance. This limits the video signal level to a lower value than the threshold during the transition period, allowing the video data to switch to a different dynamic range. This means the video receiver doesn't need to change the display's dynamic range frame by frame, for example, but only during the transition period. This simplifies dynamic range switching for the video receiver. From now on, the modalities will be described ci cbnn / ι ζπζ / ε / υιλι specifically with reference to the drawings. It should be noted that each of the embodiments described below illustrates a specific example of the present description. The numerical values, shapes, materials, structural elements, arrangement and connection of the structural elements, steps, processing order of the steps, etc., illustrated in the subsequent embodiments are merely examples and are therefore not intended to limit the present description. Additionally, among the structural elements in the following embodiments, those structural elements not set forth in any of the independent claims that represent more generic concepts are described as arbitrary structural elements. EMBODIMENT 1 A video receiving apparatus according to the present embodiment controls the dynamic range of a display's luminance in frame accuracy, using transmission characteristic information that indicates the transmission characteristics in frame accuracy. By doing so, the video receiving apparatus can display a more appropriate video. First, a configuration of the video receiving apparatus according to the present modality will be described. FIGURE 1 is a block diagram of the video receiving apparatus 100 according to the present modality. The video receiving apparatus 100 is a TV, for example, and receives a reception signal 111 transmitted via broadcast waves and displays video based on the received reception signal 111. The video receiving apparatus 100 includes the receiver 101, demultiplexer 102, video decoder 103, display controller 104, and display 105. Receiver 101 accepts reception signal 111. The 111 receive signal is a multiplexed system stream of a video signal and an audio signal. The demultiplexer 102 generates the video signal 112 which is a video stream, by demultiplexing (system decoding) the receiving signal 111. Additionally, the demultiplexer 102 sends, as the first transfer characteristic information 113, transfer characteristics obtained from, for example, a descriptor included in the received signal 111. That is, the first transfer characteristic information 113 is included in a multiplexing layer. The video decoder 103 generates video data 114 by decoding the video signal 112. Additionally, the video decoder 103 sends, as a second set of transfer characteristics 115, transfer characteristics obtained from the SPS. That is, the second set of transfer characteristics 115 is included in a video encoding layer. The second transfer characteristic information 115 specifies a frame-accurate transfer function (OETF or EOTF) that supports a luminance dynamic range for the video data 114. For example, the second transfer characteristic information 115 specifies, in frame accuracy, a first transfer function corresponding to a first luminance dynamic range (SDR) or a second transfer function corresponding to a second luminance dynamic range (HDR) that is wider than the first luminance dynamic range. In other words, the second transfer characteristic information 115 indicates whether the video data 114 is SDR video data or HDR video data. Furthermore, when there is more than one HDR method, the second transfer characteristic information 115 can indicate the HDR method.That is, the second transfer characteristic information 115 indicates the luminance dynamic range of the video data 114. For example, the second transfer characteristic information 115 indicates one of a plurality of predetermined luminance dynamic ranges. The SPS is control information included in the video signal 112. In this document, the control information is provided in a sequence-by-sequence manner (in a plurality of frames by plurality of frames manner). The display controller 104 generates control information 116 to control display 105, according to the first transfer characteristic information 113 and the second transfer characteristic information 115. The display 105 exhibits video data 114 while controlling the dynamic range of luminance in frame accuracy according to the control information 116 (i.e., the first transfer characteristic information 113 and the second transfer characteristic information 115). The display 105 includes the video characteristic converter 106 and the display device 107. The video feature converter 106 generates the input signal 117 by converting video data 114 according to the control information 116. Specifically, the video feature converter 106 transforms the video data 114 into the input signal 117 using a transfer function indicated in either the first transfer feature information 113 or the second transfer feature information. 115. The display device 107 is, for example, a liquid crystal panel, and changes the dynamic range of luminance of the displayed video, according to the control information 116. For example, when the display device 107 is a liquid crystal panel, the display device 107 changes the maximum luminance of a backlight. Next, an operation of the video receiving apparatus 100 will be described. It should be noted that although FIGURE 1 illustrates a configuration in which both the first transfer characteristic information 113 and the second transfer characteristic information 115 are used, it is only necessary that at least the second transfer characteristic information 115 be used. The control performed using the second transfer characteristic information 115 will be described in detail hereafter. FIGURE 2 is a flowchart of the display control processing performed by the display controller 104. It should be noted that the processing illustrated in FIGURE 2 is performed in a frame-by-frame mode or each time the second transfer characteristic information 115 is changed. First, the display controller 104 ci cbnn / ι ζπζ / ε / υιλι determines which of the SDR and HDR is indicated by the second transfer feature information 115 (S101). When HDR is indicated by the second transfer feature information 115 (SI in S101), the display controller 104 sends control information 116 to the HDR display (S102). This allows the display 105 to display video in a luminance dynamic range corresponding to HDR. Furthermore, when the SDR is indicated by the second transfer characteristic information 115 (NOT in S101), the display controller 104 sends control information 116 to the SDR display (S103). This causes the display 105 to exhibit video in a luminance dynamic range corresponding to the SDR. In this way, by switching control information 116 in accordance with the second transfer characteristic information 115 reported in frame accuracy, it is possible to synchronize the switching of the transfer characteristics and the control on screen 105. It should be noted that when multiple HDR methods exist (e.g., STD-B67 and ST2084), control information 116 for the HDR display may include identification information that distinguishes one HDR method. This allows display 105 to display video within the luminance dynamic range of the corresponding method. ci cbnn / ι ζπζ / β / υιλι Figure 3 is a flowchart of the video reception processing performed by the video receiving apparatus 100. First, the receiver 101 accepts the reception signal 111 (S112). Next, the demultiplexer 102 generates the video signal 112 by demultiplexing the reception signal 111 (S112). Then, the video decoder 103 generates the video data 114 and obtains the second transfer characteristic information 115 by decoding the video signal 112 (S113). Next, the display controller 104 controls the luminance dynamic range of display 105 according to the second transfer characteristic information 115. Specifically, the display controller 104 determines, for each frame, frame by frame, whether the frame is an HDR frame or an SDR frame, based on the second transfer characteristic information 115 (S114). When the frame is an HDR frame (YES in S114), display 105 displays video in the HDR luminance dynamic range (S115). When the frame is an SDR frame (NO in S114), display 105 displays video in the SDR luminance dynamic range (S116). Figure 4 illustrates the switching from an SDR program to an HDR program. Figure 5 illustrates the switching from an HDR program to an SDR program. As illustrated in Figures 4 and 5, the processing described above enables proper switching between SDR and HDR with frame accuracy. The video transmission apparatus 200, which generates the transmission signal 212 corresponding to the aforementioned reception signal 111, will be described hereafter. Figure 6 is a block diagram of a video transmission apparatus 200 according to the present embodiment. The video transmission apparatus 200 illustrated in Figure 6 includes the generator 201 and the transmitter 202. Generator 201 produces transmission signal 212, which includes video data and secondary transfer characteristic information. This information specifies, in frame accuracy, a transfer function corresponding to the dynamic range of the video data's luminance. Generator 201 includes a video encoder 203 and a multiplexer 204. Figure 7 is a flowchart of the video transmission processing performed by the video transmission apparatus 200. First, the video encoder 203 generates the video signal 211 by encoding video data and second transfer characteristic information (S201). The second transfer characteristic information corresponds to the second transfer characteristic information 115 described above, and is information to specify, in frame accuracy, the first transfer function corresponding to the first luminance dynamic range (e.g., SDR) or the second transfer function corresponding to the second luminance dynamic range (e.g., HDR) wider than the first luminance dynamic range. The second transfer characteristic information is stored in the SPS included in the video signal 211. Next, multiplexer 204 generates transmission signal 212 by multiplexing the encoded video signal 211 and an audio signal (S202). Then, transmitter 202 outputs the generated transmission signal 212 (S203). With the preceding processing, the video transmission apparatus 200 generates the transmission signal 212, which includes the second transfer characteristic information to specify a frame-accurate transfer function. With this, the video receiving apparatus that accepts the transmission signal 212 can control the dynamic range of the display's luminance in frame accuracy, and thus display a more appropriate video. MODE 2 With the TV broadcaster, a ci cbnn / i ζπζ / β / υιλι error can occur due to the condition of the radio waves from terrestrial signals, satellites, etc. FIGURE 8 illustrates the case of a reception error caused by radio interference, for example. FIGURE 8 illustrates a case where, when switching from SDR to HDR, radio interference or similar occurs after the video receiver obtains the second transfer characteristic information 115 included in the SPS, and as a result, a video stream is lost, causing the inability to obtain the initial frame of the HDR program. In this case, the video decoder 103 continues to display an immediately preceding frame to mask the error. In other words, the SDR program frame is displayed repeatedly. In this case, a subsequent plot refers to this plot, and in this way, an abnormal video mixed with video from a past program is exhibited as a subsequent video. Furthermore, immediately after switching from SDR to HDR, the display's dynamic range is set to HDR, causing the SDR program frame to be displayed in the HDR dynamic range. This results in a video display problem with a higher luminance than intended. The present embodiment describes a video receiving apparatus that solves this problem. FIGURE 9 is a block diagram of the video receiving apparatus 100A according to the present embodiment. The video receiving apparatus 100A illustrated in FIGURE 9 includes, in addition to the elements included in the video receiving apparatus 100 illustrated in FIGURE 1, an abnormality detector 108 and a message overlay device 109 included in the display 105A. Furthermore, the display controller 104A has an additional function. Anomaly detector 108 determines whether video data 114 (video signal 112) is being acquired correctly. Specifically, anomaly detector 108 detects packet loss based on the sequence number of each packet and obtains the starting position of the frame data by analyzing the payload of each packet to determine whether all frame data is being acquired (normal) or only a portion of the frame data is being acquired (abnormal). Additionally, anomaly detector 108 sends anomaly notification information 118 indicating the result of the determination to the display controller 104A. That is, the display controller 104A is notified that an abnormal condition has occurred, or is notified of information to specify an abnormal frame. ci cbnn / ι ζπζ / β / υιλι The display controller 104A generates control information 116 and a message 119 in accordance with the abnormality notification information 118 in addition to the first transfer characteristic information 113 and the second transfer characteristic information 115. Specifically, when an abnormality exists, the display controller 104A generates message 119 indicating that an abnormality exists, and generates control information 116 for the SDR display. The message overlay device 109 generates input signal 120 by overlaying message 119 onto video data (input signal 117) according to control information 116 and message 119, and sends the generated input signal 120 to the display device 107. That is, a message such as "An error has occurred" is displayed on the display device 107, notifying the viewer that there is no fault in the device. Figure 10 is a flowchart of the display control processing performed by the display controller 104A. First, the display controller 104A determines whether the second transfer characteristic information 115 is up to date (S121). When the second transfer characteristic information 115 is up to date (YES in S121), the display controller 104A initiates the determination regarding the switching of the display control. First, the 104A display controller determines whether the video data is being acquired correctly. Specifically, the 104A display controller determines whether an intra-coded frame is being decoded normally, based on the abnormality notification information 118 (S122). When the intra-coded frame is not being decoded normally (NO in S122), the 104A display controller sends control information 116 to the SDR display (S123). This causes display 105 to display video at a luminance dynamic range corresponding to the SDR. In other words, when it is determined that the video data is not being acquired correctly, the 104A display controller sets the SDR (the first luminance dynamic range) as the luminance dynamic range of display 105. If an error occurs when switching from one dynamic range of luminance to another, a displayed frame may include pixels from a frame displayed before the switch. In contrast, according to the current method, in this case, setting the display control for the SDR display as the display control makes it possible to prevent a frame from the SDR program from being displayed with the high luminance settings of HDR. When an intra-coded frame that guarantees interruption of repeat, such as HEVC IDR or CRA, is normally decoded (SI in S122), the display control is switched in the same way as in Mode 1. That is, the display controller 104A determines which of the SDR and HDR is indicated by the second updated transfer characteristic information 115 (S124). When HDR is indicated by the second transfer feature information 115 (YES in S124), the display controller 104A sends control information 116 to the HDR display (S125). Conversely, when SDR is indicated by the second transfer feature information 115 (NO in S124), the display controller 104A sends control information 116 to the SDR display (S126). In this way, the 100A video receiver, according to this mode, can prevent excessively bright video from being displayed when an error occurs, by displaying video within the SDR's luminance dynamic range when the error occurs. MODE 3 The present modality describes the details of the first transfer characteristic information 113 and the processing performed using the first transfer characteristic information 113. First, an example of the transfer characteristics obtained by the demultiplexer 102 will be described. ci cbnn / ι ζπζ / β / υιλι When MMT is used as the multiplexing scheme, the presentation timestamp (PTS) and decoding timestamp (DTS) of an access unit (equivalent to a visual representation) that comes first in the decoding order (hereafter also referred to as a primary access unit) in a random access unit called a media processing unit (MPU) can be transmitted using a descriptor.For example, according to STD-B60 of the Association of Radio Broadcasting Industries and Businesses (ARIB), either (i) the PTS of the MPU's main access unit is transferred or (ii) the DTS of the MPU's main access unit and the DTS and PTS of a subsequent access unit are transferred, as control information for a program, using an MPU timestamp descriptor or an MPU extended timestamp descriptor. FIGURE 11 illustrates an example of an MPU timestamp descriptor syntax (MPU_Timestamp_Descriptor) that includes HDR 301 identification information. FIGURE 12 illustrates an example of an MPU extended timestamp descriptor syntax (MPU_Extended_Timestamp_Descriptor) that includes HDR 301 identification information. As illustrated in Figures 11 or 12, by extending the MPU timestamp descriptor or the extended MPU timestamp descriptor, it is possible to add HDR identification information (mpu_hdr_indicator) to the transmit signal 212 (receive signal 111). This information indicates whether the access unit's EOTF is HDR or SDR. It should be noted that when two or more HDR EOTFs exist—for example, when both STD-B67 and SMPTE ST2084 are available—the HDR identification information (mpu_hdr_indicator) can include information to identify which EOTF is HDR. Additionally, a different descriptor can be used as long as the MPU-provided EOTF identification information can be transmitted. When MPEG-2 TS is used as the multiplexing scheme, the PTS or DTS of the access unit can be associated with the EOTF identification information by extending 13818-1AMD6 (providing a timeline for external data). Alternatively, the EOTF identification information provided by the random access unit can be stored using a descriptor in the same way as the MMT, or the EOTF identification information provided by the random access unit can be signaled using PES header information. TS. Thus, the first transfer characteristic information 113 is included in the control information contained in the transmit signal 212 (receive signal 111). At this point, the control information is provided per random access unit. It should be noted that a random access unit is a unit that includes a plurality of access units (a plurality of frames) in which random access is guaranteed. The first transfer characteristic information 113 can be stored in program-provided information that includes a plurality of MPUs, instead of being stored as MPU-provided information such as the MPU timestamp descriptor. According to ARIB, the resolution, aspect ratio, frame rate, etc., of a video stream are stored in a video component descriptor, which is program-provided information. In this way, the first transfer characteristic information 113 can also be stored in the video component descriptor. However, since program-provided information is transmitted periodically, for example, every 0.5 seconds or every 0.1 seconds, in some cases the information cannot be updated per frame or per random access unit.Therefore, in these cases, transfer characteristic information that will be valid in the future is stored, as well as currently valid transfer characteristic information. Figure 13 illustrates an example of a video component descriptor syntax. `Current EOTF` (first piece of information) indicates a currently valid EOTF (transfer function), and `EOTF_update_flag` (second piece of information) indicates whether the EOTF will be switched in the future. That is, `EOTF_update_flag` (second piece of information) indicates whether the transfer function will be switched or not in the program. When EOTF_update_flag (second piece of information) indicates that the EOTF will be switched, the video component descriptor includes new_EOTF (third piece of information) indicating a new EOTF to be switched to, and new EOTF start mpu sequence number (fourth piece of information) indicating the sequence number of the MPU on which the new EOTF will be valid. In other words, new EOTF start mpu sequence number (fourth piece of information) specifies a random access unit on which the EOTF will be switched. It should be noted that when an HDR type exists, it is only necessary to indicate whether the EOTF corresponds to HDR or SDR. That is, the new EOTF field can be omitted because the new EOTF can be determined solely from the EOTF update flag. By transmitting the transfer characteristics in the manner described above, the video receiving device can obtain the transfer characteristics of the access unit included in the MPU, based solely on information about the multiplexing layer (information about multiplexed AV data attributes and header information of a packet in which the AV data is stored). Additionally, with unrestricted connection according to conventional ARIB, the PID of a TS packet that stores a video stream or a resource ID (or packet ID) of an MMT packet is switched when an element such as the resolution is switched.This switching method has disadvantages; for example, it is difficult to manage a system target decoder (STD) buffer for packets with the same ID, or the transmit-side data supply is temporarily interrupted at the switching point. These problems can be resolved by adopting the present technique. It should be noted that the present technique is also applicable to the case of unrestricted switching of a plurality of audio codes. The configuration of the video receiving device ci cbnn / ι ζπζ / β / υιλι 100A according to the present mode is different from that of Mode 2 because a function is added to the 104A display controller in the configuration illustrated in FIGURE 9. First, before decoding the video signal 112, the demultiplexer 102 obtains the transfer characteristics described above (such as the HDR identification information 301) from the information about the multiplexing layer, and sends, to the display controller 104A, the first transfer characteristic information 113 to specify the obtained transfer characteristics. Since the video receiving apparatus 100A can obtain the first transfer characteristic information 113 before decoding the video signal 112, the first transfer characteristic information 113 can be obtained before the second transfer characteristic information 115 in terms of time. Consequently, it is possible to extend the time between the display controller 104A obtaining the transfer characteristic information and the actual control over the video characteristic converter 106 and the display device 107 by the display controller 104A. Especially when the transfer characteristics are switched by access unit, an increase in the frame rate places a greater constraint on time if the transfer characteristics are obtained based on the decoding result.Therefore, it is extremely beneficial to obtain the transfer characteristics of the multiplexing layer in advance. Figure 14 is a flowchart of the display control processing performed by the display controller 104A. The processing illustrated in Figure 14 differs from the processing illustrated in Figure 10 in terms of Steps S121A and S124A. In Step S121A, the display controller 104A determines whether the first transfer characteristic information 113 is updated in addition to the second transfer characteristic information 115. Furthermore, since the MPU's primary access unit is an intra-coded frame, in Step S122, the display controller 104A, when operating on the basis of the first transfer characteristic information 113, operates based on (i) the first transfer characteristic information 113 corresponding to the MPU sequence number and (ii) the result of decoding the intra-coded frame. In Step S124A, the display controller 104A operates based on either the first transfer characteristic information 113 or the second transfer characteristic information 115. It should be noted that although FIGURE 14 illustrates the example where both the first transfer characteristic information 113 and the second transfer characteristic information 115 are used, instead only the first transfer characteristic information 113 can be used. Figure 15 is a flowchart of the video reception processing performed by the video receiving apparatus 100A according to the present modality. First, the receiver 101 accepts the reception signal 111 (S112A). Then, the demultiplexer 102 generates the video signal 112 and obtains the first transfer characteristic information 113 by demultiplexing the reception signal 111 (S112A). In this document, the first transfer characteristic information 113 is information to specify, per random access unit (per MPU), a transfer function (OETF or EOTF) that corresponds to the luminance dynamic range of video data 114 (video signal 112). For example, the first transfer characteristic information 113 is information to specify, per random access unit, the first transfer function that corresponds to the first dynamic luminance range (SDR) or the second transfer function that corresponds to the second dynamic luminance range (HDR), which is wider than the first dynamic luminance range. That is, the first transfer characteristic information 113 indicates whether the video data 114 is SDR video data or HDR video data.Furthermore, when there is more than one HDR method, the first transfer feature information 113 can indicate the HDR method. That is, the first transfer feature information 113 indicates the luminance dynamic range of the video data 114. For example, the first transfer feature information 113 indicates one of a plurality of predetermined luminance dynamic ranges. Next, video decoder 103 generates video data 114 by decoding video signal 112 (S113). Next, the display controller 104A controls the dynamic luminance range of display 105 according to the first transfer characteristic information 113. Specifically, the display controller 104A determines, per MPU, whether the data in the MPU corresponds to HDR or SDR, based on the first transfer characteristic information 113 (S114A). When the data in the MPU corresponds to HDR (YES in S114A), display 105 displays video in the HDR dynamic luminance range (S115). When the data in the MPU corresponds to SDR (NO in S114A), display 105 displays video in the SDR dynamic luminance range (S116). With the above processing, the video receiving apparatus 100A can control the dynamic range of the luminance of the display 105 per random access unit, and thus can display a more suitable video. Furthermore, since the video receiving apparatus 100A can obtain the transfer characteristics before decoding the video signal 112 by using the first transfer characteristic information 113 included in the multiplexing layer, it is possible to easily switch the transfer characteristics. The configuration and operation of the video transmission apparatus 200 that generates the transmission signal 212 corresponding to the reception signal 111 described above are generally the same as those of Mode 1 described above. Specifically, in Step S202 illustrated in FIGURE 7, the multiplexer 204 generates the transmission signal 212 which includes the first transfer characteristic information 113. In this way, the video transmission device 200 generates the transmission signal 212, which includes the first ci cbnn / i ζπζ / β / υιλι transfer characteristic information to specify the transfer function per random access unit. With this, the video receiving device, which accepts the transmission signal 212, can control the dynamic range of the display luminance per random access unit, and thus display a more appropriate video. Furthermore, since the first transfer characteristic information 113 is included in the multiplexing layer, the video receiving device can easily switch the transfer characteristics. From now on, a variation of the present modality will be described. In the case where a video receiving device such as an external set-top box (STB), DVD player, or Blu-ray player (registered trademark) receives a system stream and sends a stream to a display device such as a TV, the video receiving device and the display device are connected via a communication protocol such as HDMI (registered trademark). In this document, with HDMI (registered trademark), etc., protocol re-authentication occurs when the resolution or similar aspect of the stream is switched. ci cbnn / ι ζπζ / β / υιλι Therefore, if there is a possibility that the resolution will be switched, for example, between 2K (e.g., 1920 x 1080 pixels) and 4K (e.g., 3840 x 2160 pixels), the video receiver should ideally send a video signal compatible with the maximum resolution when playback begins. That is, if there is a mix of 2K and 4K streams, the receiver upconverts the 2K streams to 4K and sends the 4K streams, even if playback starts with the 2K streams. By doing so, even if a signal is switched to a 4K signal mid-stream, the resolution remains at 4K, and the resolution switching does not occur. For example, when switching between 2K SDR and 4K HDR, the video receiving device converts a 2K stream for SDR into a 4K stream for SDR, and sends the 4K stream for SDR. In other words, the video signal (video data 114) has a resolution that is either a first resolution or a second resolution higher than the first resolution. When the video signal resolution switches between the first and second resolutions, the 100A video receiver converts the video signal with the first resolution into the video signal with the second resolution. In broadcasting, the identification information ci cbnn / i ζπζ / β / υιλι, which distinguishes the maximum permissible resolution for the broadcast service, is indicated, for example, by a descriptor. This allows the video receiving device to operate in such a way that the HDMI output signal (a registered trademark) consistently maintains the maximum resolution. For example, in the case of Ultra High Definition (UHD) service, the maximum resolution is defined as 4K or 8K. When the multiplexing scheme is TS, the maximum resolution is defined as 2K, while when the multiplexing scheme is MMT, the maximum resolution is defined as 4K. Consequently, the video receiving device can continuously convert the video signal to a video signal with the maximum resolution supported by the multiplexing scheme and can then transmit the video signal with that maximum resolution. That is, when the resolution of the video signal (video data 114) is lower than the maximum resolution defined by the broadcast service for the reception signal 111, the video receiving apparatus 100A converts the resolution of the video signal to the maximum resolution. MODALITY 4 In this mode, the video signal level is limited when the luminance dynamic range is switched between SDR and HDR. This makes easier switching of the luminance dynamic range by the video receiver possible. First, the interchangeable features of STD-B67 that correspond to HDR will be described. In terms of device design, it is important to allow a certain delay length between when the transfer features are obtained and when the video feature converter 106 and the display device 107 are controlled. As an example where this delay is permitted, it has been previously described that the switching of the transfer features is announced in advance using a descriptor in a multiplexing layer. However, even when the switching of transfer features is notified in advance, it is necessary to control the video feature converter 106 and the display device 107 in synchronization with a frame that switches from SDR to HDR or from HDR to SDR. Meanwhile, when the luminance value of the SDR (BT.2020, for example) at the electrical signal level of 1.0 is adjusted to a level in the order of 400% to 500% with respect to 1200% for STD-B67 (HDR), the shape of a curve showing a relationship between the electrical signal level and the luminance of STD-B67 generally coincides with the shape of a curve for the SDR at low luminance. ci cbnn / ι ζπζ / β / υιλι Figure 16 illustrates an example of a curve showing the relationship between the electrical signal level and luminance of HDR (STD-B67) and a curve showing the relationship between the electrical signal level and luminance of SDR (BT.2020) according to Mode 4. As illustrated in Figure 16, the HDR and SDR curves generally coincide in the low-luminance range. Thus, if the luminance range of the HDR video data converted by STD-B67 is equivalent to the luminance range in which the shapes of the curves described above generally coincide, even a display device that only supports SDR can reproduce video that does not produce a sense of visual strangeness for the viewer. In other words, STD-B67 has interchangeable characteristics between SDR and HDR.Henceforth, a range of electrical signal level corresponding to the luminance range in which the SDR curve shape and the HDR (STD-B67) curve shape generally coincide is referred to as an interchangeable region. In other words, as illustrated in FIGURE 16, the interchangeable region is a predetermined range of electrical signal level, and it is a range of electrical signal level lower than a predetermined threshold value. For example, in FIGURE 16, an electrical signal level A is within the switchable region, and thus STD-B67 and BT.2020 are equivalent in luminance value. On the other hand, the luminance value corresponding to electrical signal level B is ni for BT.2020 and n2 for STD-B67, which are significantly different from each other. This results in a problem when switching from HDR to SDR. For example, if there is a delay in the video receiver's switching of the transfer characteristics, and SDR pixels outside the switchable region are thus reproduced as HDR pixels in error, the pixels are reproduced at an inappropriately high luminance value. A method for providing a transition period in the switching of transmission characteristics according to the present modality will be described below. By using the interchangeable characteristics described above, it is possible to display video that does not give the viewer a sense of strangeness even when the video receiving apparatus does not switch the transmission characteristics in synchronization with the frame. First, with reference to FIGURE 17, an operation performed to switch from an SDR program to an HDR program will be described. A certain period of time at the end of the SDR program is established as a transition period from SDR to HDR (a transition period). During the transition period, video data is generated using the electrical signal level within the switchable region. By doing so, regardless of whether the control settings for the SDR display or the control settings for the HDR display are used during the transition period, a video with a visually equivalent luminance is reproduced. In this way, it is possible to prevent the playback of video at an inappropriately high luminance. The switching of transfer characteristics can be notified using information included in the multiplexing layer, such as the video component descriptor illustrated in Figures 11 to 13. In this document, since the transition period is T seconds and the allowable time for the video receiving apparatus to switch transfer characteristics (allowable switching time) is S seconds, a descriptor notifying the switching of transfer characteristics is transmitted within (TS) seconds of the start of the transition period. By switching the display control within S seconds of obtaining the descriptor, the video receiving apparatus can complete the display control switching before the HDR program starts. In this way, by providing the transition period and restricting the highest luminance of the image during the transition period, and notifying the switching of the transfer characteristics using the multiplexing layer, the video receiving apparatus can switch the control of the display based solely on the information included in the multiplexing layer without having to analyze the video stream (video signal 112). It should be noted that the transition period can be reported as video stream information such as an SEI message, although video stream analysis is required. Next, an operation performed to switch from an HDR program to an SDR program will be described. In this case, too, the transition period can be provided in the same way as in the operation performed to switch from an SDR program to an HDR program described above. In this document, when HDR pixels outside the switchable luminance range are reproduced as SDR pixels, the pixels are reproduced at a lower luminance value than the actual luminance value. Therefore, this reproduction in this case is less likely to adversely affect the viewer in terms of health, etc. As such, as illustrated in FIGURE 18, for switching from an HDR program to an SDR program, the range of the electrical signal level does not need to be limited to the switchable region during the transition period. It should be noted that the switchable region described above is a predetermined range of electrical signal level, and it is a range of electrical signal level lower than a predetermined threshold. For example, NPL 2 describes the characteristics of those SDR and HDR curves (page 9, Figure 3, for example). That is, the lower threshold of the switchable region is an electrical signal level of 0, i.e., black. A video transmission apparatus and a video reception apparatus implementing the above function will be described below. Figure 19 is a block diagram of the video transmission apparatus 200B according to the present embodiment. The video transmission apparatus 200B includes the generator 201B and the transmitter 202. The generator 201B produces the transmission signal 212B, which includes, in a time series, first video data having a first luminance dynamic range (SDR) and second video data having a second luminance dynamic range (HDR) wider than the first luminance dynamic range (SDR). The generator 201B includes the video data generator 205, the video encoder 203, and the multiplexer 204. The transmitter 202 outputs the transmission signal 212B. Figure 20 is a flowchart of the video transmission processing performed by the video transmission apparatus 200B. First, the video data generator 205 produces the video data 213 (S204). At that point, the video data generator 205, as described above, limits the signal level corresponding to the luminance value to a level within the switchable region during the transition period provided to switch from one of the first video data and the second video data to the other. That is, the video data generator 205 limits the signal level to a value lower than a predetermined limit. The transition period is the period immediately preceding the switching time, for example. Additionally, as described above, the signal level is limited only when the luminance dynamic range is switched from SDR to HDR, and the signal level does not need to be limited when the luminance dynamic range is switched from HDR to SDR. That is, the signal level corresponding to the luminance value can be limited to a lower value than the limit value during the first transition period provided for switching from the first video data (SDR) to the second video data (HDR), while the signal level corresponding to the luminance value does not need to be limited to a lower value than the limit value during the second transition period provided for switching from the second video data (HDR) to the first video data (SDR). Next, video encoder 203 generates video signal 211B by encoding video data 213 (S201). Then, multiplexer 204 generates transmission signal 212B by multiplexing the generated video signal 211B and an audio signal (S202). Finally, transmitter 202 outputs transmission signal 212B (S203). As illustrated in Figures 17 and 18, the 212B transmission signal includes initial information (a switching notification descriptor) to notify the switching of the luminance dynamic range in a first period immediately following the start of the transition period. For example, the first period is a time interval from immediately after the start of the transition period until a time preceding a switching time, by an allowable switching time, which is the length of time allowed for the luminance dynamic range switching by the video receiving apparatus accepting the 212B transmission signal. ci cbnn / ι ζπζ / β / υιλι The first piece of information (the switch-off notification descriptor) is transmitted using the multiplexing layer. Specifically, multiplexer 204 generates the 212B transmission signal, which includes the first piece of information (the switch-off notification descriptor), by multiplexing the 211B video signal and an audio signal. The 212B transmission signal may also include a second piece of information indicating the transition period. Figure 21 is a block diagram of the video receiving apparatus 100B according to the present modality. The video receiving apparatus 100B accepts the receiving signal 111B, which is the transmitting signal 212B generated by the video transmitting apparatus 200B illustrated in Figure 19. It should be noted that the basic configuration is the same as that of the video receiving apparatus 100 illustrated in Figure 1, but the function of the display controller 104B is different from that of the display controller 104. Figure 22 is a flowchart of the video reception processing performed by the video receiving apparatus 100B. First, receiver 101 accepts the reception signal 111B, which includes, in a time series, first video data having a first luminance dynamic range (SDR) and second video data having a second luminance dynamic range (HDR) wider than the first luminance dynamic range (SDR) (Slll). In this document, as described above, in the reception signal 111B, the signal level corresponding to the luminance value is limited to a value lower than a predetermined threshold during the transition period provided to switch from one of the first video data and the second video data to the other. Next, demultiplexer 102 obtains video signal 112 by demultiplexing receive signal 111B, which is multiplexed from a video signal and an audio signal (S112). The multiplexing layer includes switching notification descriptor 121 (the first piece of information), and demultiplexer 102 obtains switching notification descriptor 121. In this document, switching notification descriptor 121 is information used to notify the switching of the luminance dynamic range in the first period immediately following the start of the transition period. When the switching notification descriptor 121 (SI in S114B) is received, the display controller 104B switches the dynamic luminance range of display 105 for the allowable switching time, which begins when the switching notification descriptor 121 (S115B) is received. In this document, the allowable switching time is the length of time allowed for switching the dynamic luminance range. It should be noted that although not illustrated, video decoder 103 obtains video data 114 by decoding video signal 112 in parallel with the processing in steps S114B and S115B. Display 105 exhibits video data 114 in the currently set luminance dynamic range. As described earlier, in this mode, the video data signal level is limited to a lower value than the threshold during the transition period provided for switching to video data with a different dynamic range. This eliminates the need for the video receiver to change the display's dynamic range frame by frame, for example, and only needs to change the display's dynamic range during the transition period. In this way, the video receiver can easily control the dynamic range switching. Previously in this document, the video receiving apparatus and the video transmitting apparatus have been described in accordance with modalities of the present description; however, the present description is not limited to those modalities. Furthermore, each of the processing components included in the video receiving and transmitting apparatus, according to the above methods, is typically implemented as an LSI, which is an integrated circuit. These can be implemented individually on a single chip, or on a single chip that includes some or all of them. Furthermore, the circuit integration method is not limited to LSIs. Integration can be implemented with a specialized circuit or a general-purpose processor. It is also acceptable to use: a field-programmable gate array (FPGA) that is programmable after the LSI is manufactured; and a reconfigurable processor that allows for the reconfiguration of connections and adjustments to the internal circuit cells of the LSI circuit. Furthermore, in each modality described above, each structural element can be implemented by means of specialized hardware (physical components) or by means of the execution of a software program appropriate for the structural element. Each structural element can also be implemented by means of reading and executing, by means of a program execution unit such as a central processing unit (CPU) or a processor, a software program recorded on a recording medium such as a hard disk or semiconductor memory. Furthermore, the present description can be implemented as a method of video reception performed by a video receiving apparatus or as a method of video transmission performed by a video transmitting apparatus. The division of functional blocks in block diagrams is a simple example. A plurality of functional blocks can be implemented as a single functional block, or a functional block can be divided into a plurality of blocks, or some of its functions can be transferred to another functional block. Furthermore, the functions of a plurality of functional blocks that have similar functions can be performed by a single piece of hardware or software in parallel or by time-splitting. Additionally, since the processing order of the steps in each flowchart is an example provided to specifically illustrate this description, other processing orders may be adopted. Furthermore, some steps may be performed simultaneously (in parallel) with others. Earlier in this document, a video receiving apparatus and a video transmitting apparatus have been described according to one or more aspects based on ci cbnn / i ζπζ / β / υιλι modalities; however, the present description is not limited to those modalities. Various modifications to those modalities that are conceivable to those skilled in the field, as well as modalities resulting from combinations of structural elements from different modalities, may be included within the scope of one or more aspects, provided that these modifications and modalities do not depart from the essence of the present description. INDUSTRIAL APPLICABILITY This description applies to a video receiving apparatus such as a TV and a video transmitting apparatus. REFERENCE MARKS ON THE FIGURES 100, 100A, 100B video receiving apparatus 101 receiver 102 demultiplexer 103 video decoder 104, 104A, 104B Display Controller 105, 105A screen 106 video feature converter 107 display device 108 abnormality detector 109 Device for overlaying messages 111 , 111B receive signal ci cbnn / ι ζπζ / β / υιλι 112, 211, 211B video signal 113 First transfer characteristics information 114,213 video data 115 Second transfer characteristics information 116 control information 117, 120 input signal 118 Abnormality notification information 119th message 121 switch notification descriptor 200, 200B video transmission apparatus 201, 201B generator 202 transmitter 203 video encoder 204 demultiplexer 205 video data generator 212, 212B transmission signal 301 HDR identification information It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A video transmission method, comprising: generating (S204, S201, S202) a transmission signal (212B) comprising, in a time series, first video data having a first luminance dynamic range and second video data having a second luminance dynamic range wider than the first luminance dynamic range;and transmit (S203) the generated transmission signal (212B), characterized in that in the generation of the transmission signal (212B), a signal level corresponding to a luminance value is limited to a value in an interchangeable region, where a form of a first transfer characteristic curve of the first luminance dynamic range and a form of a second transfer characteristic curve of the second luminance dynamic range generally coincide, the value being lower than a predetermined limit value, in a transition period provided for switching from one of the first video data and the second video data to the other; and transfer characteristic information is provided in the transmission signal (212B) and is transmitted periodically.

2. The video transmission method according to claim 1, characterized in that the transmission signal is multiplexed by an MPEG media transport scheme, MMT, or a transport stream, TS, scheme.

3. The video transmission method according to claim 1 or 2, characterized in that the transfer characteristic information is provided in Program Specific Information, PSI, or MPEG Media Transport Service Information, MMT-SI, of a multiplexed stream.

4. The video transmission method according to any of claims 1 to 3, characterized in that information is provided to specify frame accuracy transfer characteristics in a sequence parameter set, SPS, of a video stream.

5. A video reception method implemented by a video receiving apparatus (100B) including a display (105), the video reception method comprising: receiving (111B) a receiving signal (111B) comprising, in a time series, first video data having a first luminance dynamic range and second video data having a second luminance dynamic range wider than the first luminance dynamic range, characterized in that in the receiving signal (111B), a signal level corresponding to a luminance value is limited to a value in an interchangeable region, where a shape of a first transfer characteristic curve of the first luminance dynamic range and a shape of a second transfer characteristic curve of the second luminance dynamic range generally coincide, the value being lower than a predetermined limit value,in a transition period provided for switching from one of the first video data and the second video data to the other, and transfer characteristic information is provided in the receiving signal (111B) and is received periodically, the video receiving method further comprises: switching (S115B) the dynamic luminance range of the display (105) for a time allowed for switching, the time allowed for switching being a length of time allowed for switching the dynamic luminance range.

6. The video reception method according to claim 5, characterized in that the reception signal (111B) is multiplexed by an MPEG media transport, MMT, scheme or a transport stream, TS, scheme.

7. The video reception method according to claim 5 or 6, characterized in that the transfer characteristic information is provided in Program Specific Information, PSI, or MPEG Media Transport Service Information, MMT-SI, of a multiplexed stream.

8. The video reception method according to any of claims 5 to 7, characterized in that information is provided to specify frame accuracy transfer characteristics in a sequence parameter set, SPS, of a video stream.

9. A video transmission apparatus, comprising a generator (201B) that generates a transmission signal (212B) that includes, in a time series, first video data having a first dynamic range of luminance and second video data having a second dynamic range of luminance wider than the first dynamic range of luminance;and a transmitter (202) that transmits the generated transmission signal (212B), characterized in that the generator (201B) limits a signal level corresponding to a luminance value to a value in an interchangeable region, where a form of a first transfer characteristic curve of the first luminance dynamic range and a form of a second transfer characteristic curve of the second luminance dynamic range generally coincide, the value being lower than a predetermined limit value, in a transition period provided for switching from one of the first video data and the second video data to the other; and transfer characteristic information provided in the transmission signal (212B) is transmitted periodically.

10. A video receiving apparatus including a display (105), the video receiving apparatus comprising: a receiver (101) receiving a receiving signal (111B) comprising, in a time series, first video data having a first luminance dynamic range and second video data having a second luminance dynamic range wider than the first luminance dynamic range, characterized in that in the receiving signal (111B), a signal level corresponding to a luminance value is limited to a value in an interchangeable region, wherein a shape of a first transfer characteristic curve of the first luminance dynamic range and a shape of a second transfer characteristic curve of the second luminance dynamic range generally coincide, the value being lower than a predetermined limit value,in a transition period provided for switching from one of the first video data and the second video data to the other, and transfer characteristic information provided in the receiving signal (111B) is received periodically, the video receiving apparatus further comprises: a display controller (104B) that switches the dynamic range of luminance of the display (105) for a time allowed for switching, the time allowed for switching being a length of time allowed for switching the dynamic range of luminance.

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