Data generator, data output device, encoder, and decoding device

Abstract

To provide a data generator capable of achieving backward compatibility.SOLUTION: The data generator generates a video elementary stream of a second luminance dynamic range wider than a first luminance dynamic range. The video elementary stream includes: first transfer function information for identifying a first OETF that is referred to by a first device when the first device decodes a video elementary stream; and a second transfer function information for identifying a second OETF that is referred to by a second device when the second device decodes the video elementary stream.SELECTED DRAWING: Figure 13

Description

Technical Field

[0001] The present invention relates to a data generation method, a data reproduction method, a data generation device, and a data reproduction device.

Background Art

[0002] As technologies for generating, encoding, and multiplexing video, there are the technologies described in Non-Patent Documents 1 to 3.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the generation of such video data, although new methods are constantly being devised, it is desired to achieve backward compatibility with conventional devices.

[0005] Therefore, an object of the present invention is to provide a data generation method, a data reproduction method, a data generation apparatus, or a data reproduction apparatus capable of achieving backward compatibility.

Means for Solving the Problems

[0006] In order to achieve the above object, a data generation apparatus according to an aspect of the present invention is a data generation apparatus that generates a video elementary stream having a second luminance dynamic range wider than a first luminance dynamic range, and includes an encoding unit that generates the video elementary stream by performing encoding conforming to a video encoding standard. The video elementary stream includes first transfer function information for specifying a first OETF referenced by a first device when the first device decodes the video elementary stream, and second transfer function information for specifying a second OETF referenced by a second device when the second device decodes the video elementary stream.

[0007] These general or specific aspects may be implemented by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be implemented by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

Effects of the Invention

[0008] The present invention can provide a data generation method, a data reproduction method, a data generation apparatus, or a data reproduction apparatus capable of achieving backward compatibility.

Brief Description of the Drawings

[0009]

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[0010] (Knowledge on which the present invention is based) In order to maintain the dark gradation in conventional images and to express bright light such as specular reflection light that cannot be expressed by current TV signals with a brightness closer to reality, a brightness range in which the maximum brightness value is expanded is adopted. HDR (High Dynamic Range) has attracted attention. Specifically, the method of the brightness range corresponding to conventional TV signals is called SDR (Standard Dynamic Range), and the maximum brightness value was 100 nit, whereas in HDR, it is assumed that the maximum brightness value is expanded up to 1000 nit or more.

[0011] On the other hand, it is desired that such video data corresponding to HDR can be played back even on a playback device that only supports conventional SDR. That is, video data that can be played back as HDR video on a playback device corresponding to HDR and as SDR video on a playback device corresponding to SDR is desired.

[0012] A data generation method according to an aspect of the present invention is a video data having a second luminance dynamic range wider than a first luminance dynamic range, which does not support playback of video of the second luminance dynamic range and is compatible with playback on a first device that supports playback of video of the first luminance dynamic range. A data generation method for generating video data, the method comprising: generating a video signal included in the video data using a second OETF (Opto-Electrical Transfer Function) referred to in the second device when the second device corresponding to playback of video of the second luminance dynamic range decodes the video data; storing first transfer function information for specifying a first OETF referred to in the first device when the first device decodes the video data in VUI (Video Usability Information) in the video data; and storing second transfer function information for specifying the second OETF in SEI (Supplemental enhancement information) in the video data.

[0013] According to this, on a device that only supports playback of video with a first luminance dynamic range, the video data can be played back using the first transfer function information, and on a device that supports playback of video with a second luminance dynamic range, the video data can be played back using the second function information. In this way, the data generation method can generate backward-compatible video data.

[0014] For example, the data generation method may further include a step of storing, in a descriptor of a multiplexing layer, hybrid information indicating whether the video data is video data of the second luminance dynamic range.

[0015] According to this, in a data playback device that plays back video data, it is possible to prepare for switching the playback method in advance by using the hybrid information in the multiplexing layer. Thereby, the switching of the playback method in the data playback device can be performed smoothly.

[0016] For example, the first OETF may be an OETF defined by a linear term of the luminance of the video data in a first range of the luminance of the video data and defined by a power term of the luminance of the video data in a second range larger than the first range.

[0017] For example, the second OETF may be an OETF defined by a linear term of the luminance of the video data in a third range of the luminance of the video data, defined by a power term of the luminance of the video data in a fourth range larger than the third range, and defined by a logarithmic term of the luminance of the video data in a fifth range larger than the fourth range.

[0018] For example, the first OETF may be an OETF defined by a power term of the luminance of the video data.

[0019] For example, the second OETF may be an OETF defined by a power term of the luminance of the video data in a sixth range of the luminance of the video data and defined by a logarithmic term of the luminance of the video data in a seventh range larger than the sixth range.

[0020] For example, the first OETF may be an OETF defined by BT.709 or BT.2020, and the second OETF may be a hybrid gamma OETF.

[0021] For example, the data generation method may further include a step of storing, in the SEI, dynamic range increase information indicating a difference between the luminance dynamic range of the video data and the first luminance dynamic range.

[0022] For example, the data generation method may further include a step of storing, in the SEI, picture maximum average level information indicating the maximum average luminance value among the average luminance values of each of all the pictures included in the video sequence.

[0023] Further, a data playback method according to an aspect of the present invention is a data playback method for playing back video data having a second luminance dynamic range wider than a first luminance dynamic range, the video data being incompatible with playback on a first device that does not support playback of the video having the second luminance dynamic range and supports playback of the video having the first luminance dynamic range, the video data including VUI (Video Usability Information) storing first transfer function information for specifying a first OETF (Opto-Electrical Transfer Function) referred to by the first device when the first device decodes the video data, and SEI (Supplemental enhancement information) storing second transfer function information for specifying a second OETF referred to by a second device when the second device that supports playback of the video having the second luminance dynamic range decodes the video data, the data playback method including a step of acquiring the second transfer function information included in the SEI, and a step of playing back a video signal included in the video data with reference to the second OETF specified by the acquired second transfer function information.

[0024] According to this, the data playback method can play back backward-compatible video data.

[0025] For example, the video data further includes hybrid information stored in a multiplexing layer descriptor indicating whether the video data is video data of the second luminance dynamic range. The data playback method further includes: obtaining the hybrid information from the video data; based on the obtained hybrid information, preparing to switch between playback of the first luminance dynamic range and playback of the second luminance dynamic range; and at the timing when the video sequence switches, switching between playback of the first luminance dynamic range and playback of the second luminance dynamic range.

[0026] According to this, preparation for switching the playback method can be performed in advance using the hybrid information in the multiplexing layer. Thereby, the switching of the playback method can be performed smoothly.

[0027] For example, the first OETF may be an OETF defined by a linear term of the luminance of the video data in a first range of the luminance of the video data and defined by a power term of the luminance of the video data in a second range larger than the first range.

[0028] For example, the second OETF may be an OETF defined by a linear term of the luminance of the video data in a third range of the luminance of the video data, defined by a power term of the luminance of the video data in a fourth range larger than the third range, and defined by a logarithmic term of the luminance of the video data in a fifth range larger than the fourth range.

[0029] For example, the first OETF may be an OETF defined by a power term of the luminance of the video data.

[0030] For example, the second OETF may be an OETF defined by a power term of the luminance of the video data in a sixth range of the luminance of the video data and defined by a logarithmic term of the luminance of the video data in a seventh range larger than the sixth range.

[0031] For example, the first OETF is an OETF defined by BT.709 or BT.2020, and the second OETF may be a hybrid gamma OETF.

[0032] For example, the data playback method may further include a step of obtaining, from the SEI, dynamic range increase information indicating a difference between the luminance dynamic range of the video data and the first luminance dynamic range.

[0033] For example, the data playback method may further include a step of obtaining, from the SEI, picture maximum average level information indicating the maximum average luminance value among the average luminance values of each of all the pictures included in the video sequence.

[0034] Also, a data generation device according to an aspect of the present invention is a data generation device that generates video data having a second luminance dynamic range wider than the first luminance dynamic range, which is not compatible with playback of video having the second luminance dynamic range and is compatible with playback on a first device compatible with playback of video having the first luminance dynamic range. The data generation device includes: a generation unit that generates a video signal included in the video data using a second OETF (Opto-Electrical Transfer Function) referred to by a second device when the second device, which is compatible with playback of video having the second luminance dynamic range, decodes the video data; a first storage unit that stores first transfer function information for specifying a first OETF referred to by the first device when the first device decodes the video data in VUI (Video Usability Information) in the video data; and a second storage unit that stores second transfer function information for specifying the second OETF in SEI (Supplemental enhancement information) in the video data.

[0035] According to this, in a device that only supports playback of video with a first luminance dynamic range, video data can be played back using the first transfer function information, and in a device that supports playback of video with a second luminance dynamic range, video data can be played back using the second function information. Thus, the data generation device can generate backward-compatible video data.

[0036] Also, a data playback device according to one aspect of the present invention is a data playback device that plays back video data with a second luminance dynamic range wider than the first luminance dynamic range, which is compatible with playback on a first device that does not support playback of video with the second luminance dynamic range and supports playback of video with the first luminance dynamic range. The video data includes VUI (Video Usability Information) storing first transfer function information for specifying a first OETF (Opto-Electrical Transfer Function) referenced by the first device when the first device decodes the video data, and SEI (Supplemental enhancement information) storing second transfer function information for specifying a second OETF referenced by a second device when the second device that supports playback of video with the second luminance dynamic range decodes the video data. The data playback device includes an acquisition unit that acquires the second transfer function information included in the SEI, and a playback unit that plays back a video signal included in the video data with reference to the second OETF specified by the acquired second transfer function information.

[0037] According to this, the data playback device can play back backward-compatible video data.

[0038] Note that these general or specific aspects may be implemented by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be implemented by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0039] Hereinafter, embodiments will be specifically described with reference to the drawings.

[0040] Note that all of the embodiments described below show a specific example of the present invention. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, order of steps, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. In addition, among the components in the following embodiments, the components not described in the independent claims indicating the highest-level concept are described as optional components.

[0041] In addition, detailed descriptions of terms, data configurations, processing contents, etc. may be omitted below, but one example of these specific examples conforms to the contents described in, for example, Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3.

[0042] First, the configuration of the system according to the present embodiment will be described. FIG. 1 is a block diagram showing the configuration of the system according to the present embodiment. The system shown in FIG. 1 includes a data generation device 110 and a data reproduction device 120.

[0043] The data generation device 110 generates video data having a second luminance dynamic range (e.g., HDR) wider than a first luminance dynamic range (e.g., SDR), which is incompatible with playback of video with the second luminance dynamic range and is compatible with playback on a first device that is compatible with playback of video with the first luminance dynamic range.

[0044] This data generation device 110 includes a video signal generation unit 111, an encoding unit 112, and a multiplexing unit 113.

[0045] The video signal generation unit 111 converts the luminance value of the original image corresponding to HDR into a code value using an OETF (Opto-Electrical Transfer Function). Here, as shown in FIG. 2, the OETF is a function for converting the luminance value of the original image into a code value. Specifically, the video signal generation unit 111 uses an SDR-compatible HDR OETF. The details will be described later.

[0046] The encoding unit 112 generates a video elementary stream by encoding the obtained code value in accordance with a video encoding standard such as HEVC. The multiplexing unit 113 generates a transport stream (e.g., a DVB transport stream) by multiplexing the video elementary stream.

[0047] The generated transport stream is transmitted to the data playback device 120 by, for example, a broadcast wave. Here, an example using a broadcast wave is described, but transmission via a network or the like may also be used, or transmission via a recording medium such as a BD disc may also be used.

[0048] The data playback device 120 plays back the video data generated by the data generation device 110. This data playback device 120 includes a de-multiplexing unit 121, a decoding unit 122, and a playback unit 123.

[0049] The de-multiplexing unit 121 generates a video elementary stream by de-multiplexing the video data (transport stream). The decoding unit 122 generates a code value by decoding the obtained video elementary stream in accordance with a video encoding standard such as HEVC.

[0050] The reproduction unit 123 restores the video by converting the obtained code value into a luminance value using the EOTF (Electro-Optical Transfer Function) corresponding to the above OETF. Here, the EOTF is the inverse function of the OETF and is a function for converting the code value into a luminance value. The obtained video is displayed on a display unit or the like provided in or connected to the data reproduction device 120.

[0051] Hereinafter, the signaling of the transfer function (OETF) of the present embodiment will be described.

[0052] The transfer function is signaled using transfer_characteristics in the VUI (Video Usability Information) included in the SPS (Sequence Parameter Set) in the HEVC and AVC video coding standards.

[0053] Also, only the OETF is signaled and the EOTF is not signaled.

[0054] FIG. 3 is a diagram showing the syntax of the VUI parameters. As shown in FIG. 3, the VUI includes first transfer function information (transfer_characteristics). FIG. 4 is a table showing the meaning of transfer_characteristics. The values 1 and 14 are assigned to the OETF of SDR supported by a DVB (Digital Video Broadcasting) UHD (Ultra HD) phase 1 receiver.

[0055] As described in Non-Patent Document 1 and the like, transfer_characteristics indicate the opto-electrical voltage characteristics of the original image.

[0056] Note that signaling means including, in the transmission signal, a signal for specifying the desired information within the transmission signal or a signal indicating the information itself so that the receiving side can acquire the desired information. For example, in the examples of FIGS. 3 and 4, transfer_characteristics for specifying the OETF are included in the transmission signal, and the receiving side specifies the OETF based on the received transfer_characteristics.

[0057] Hereinafter, an example of an extension for the new OETF according to this embodiment will be described.

[0058] In the HEVC and AVC standards, reserved values for further extension are provided. Therefore, this reserved value can be assigned to an SDR-compatible HDR OETF (hereinafter referred to as a hybrid OETF). For example, as shown in FIG. 5, the hybrid OETF is assigned to the values 18 to 20 which are reserved values.

[0059] However, in this case, an old-specification data playback device (receiver) that does not support HDR cannot recognize this new value and will recognize it as a reserved value. As a result, there is a problem that backward compatibility cannot be achieved when a new value is used for the hybrid OETF. Here, the hybrid OETF is an OETF that includes a part expressed by a power of luminance and a part expressed by a logarithm of luminance, such as the BBC Hybrid Gamma OETF.

[0060] In this embodiment, the value of the first transfer function information (transfer_characteristics) is set to 1 (BT.709) or 14 (BT.2020) as in the conventional SDR.

[0061] Also, second transfer function information (HDR_transfer_characteristic) is signaled separately from the first transfer function information to identify the hybrid OETF. Thus, in a data playback device that does not support HDR, the OETF for SDR can be identified using the first transfer function information (transfer_characteristics), and in a data playback device that supports HDR, the OETF for HDR can be identified using the second transfer function information.

[0062] Here, the second transfer function information (HDR_transfer_characteristic) is used for signaling the OETF for HDR. Specifically, the OETF for HDR is compatible with the OEFT for SDR identified by the first transfer function information (transfer_characteristics).

[0063] For example, the second transfer function information (HDR_transfer_characteristic) indicates any one of the three hybrid OETFs shown in FIG. 5. Note that the second transfer function information may be information indicating whether a hybrid OETF is used. Also, the number of selectable hybrid OETFs may be arbitrary as long as it is 1 or more.

[0064] Also, as shown in FIG. 2, the hybrid OETF has characteristics that substantially match those of the SDR OETF in the low luminance range. That is, the luminance reproduced in the low luminance range is substantially the same whether the video signal generated using the hybrid OETF is played back using the hybrid OETF or using the SDR OETF. Thus, the difference in luminance values between when played back on an HDR device and when played back on an SDR device can be reduced, so that a video with less discomfort can be played back even when played back using the SDR OETF.

[0065] The following describes multiple methods for storing the second transfer function information. Broadly speaking, there are a method of storing the second transfer function information in the Video Coding Layer and a method of storing it in the Multiplaxing Layer.

[0066] First, a method of storing the second transfer function information in the video coding layer will be described.

[0067] FIG. 6 is a diagram showing the syntax of an HDR hybrid gamma SEI message (hereinafter referred to as a hybrid SEI message) according to the present embodiment. As shown in FIG. 6, the second transfer function information (HDR_transfer_characteristic) is included in the hybrid SEI message.

[0068] The hybrid SEI message exists only within an IRAP NAL unit or an I picture and is valid for subsequent encoded video sequences.

[0069] Note that the hybrid SEI message may be a prefix or suffix SEI message.

[0070] Also, within the application standardization document, the presence of this SEI message may be made mandatory when HDR_transfer_characteristi is a predetermined fixed value.

[0071] Also, as shown in FIG. 7, the hybrid SEI message may include, in addition to or instead of the second transfer function information, dynamic_range_increase and maximum_average_picture_level information.

[0072] The dynamic range increase information (dynamic_range_increase) is used in the calculation of the coefficient k and takes only values of 0, 1, or 2. The coefficient k indicates the difference from the dynamic range of the SDR and is obtained by the following (Equation 1). Specifically, the coefficient k indicates the magnification of the dynamic range of the video with respect to the dynamic range of the SDR.

[0073] k = 2 × dynamic_range_increase + 4 ···(Equation 1)

[0074] The picture maximum average level information (maximum_average_picture_level) indicates the maximum average picture level among all the pictures included in the video sequence. Here, the average picture level is the average value of the luminance of the pixels expressed as a percentage with respect to the maximum luminance.

[0075] In this way, by using the dynamic range increase information and the picture maximum average level information, the difference from the SDR can be set to an arbitrary range.

[0076] Also, in the application standardization document, the presence of this SEI message may be made obligatory when k is a predetermined fixed value. For example, in DVB, k = 4, and in BDA, k = 8.

[0077] Figure 8 is a diagram showing the configuration of the extended SPS. As shown in Figure 8, the dynamic range increase information (dynamic_range_increase) and the picture maximum average level information (maximum_average_picture_level) may be included in the SPS.

[0078] Next, a method of storing the second transfer function information in the multiplexing layer will be described.

[0079] Figure 9 is a diagram showing the configuration of a hybrid descriptor (HDR_hybrid_gamma_descriptor), which is a new descriptor at the MPEG2-TS level according to the present embodiment.

[0080] As shown in FIG. 9, the hybrid descriptor includes a hybrid OETF flag (HDR_hybrid_gamma_OETF_flag) and second transfer function information (HDR_transfer_characteristic).

[0081] The hybrid OETF flag (HDR_hybrid_gamma_OETF_flag) indicates whether the content is HDR-encoded using the hybrid OETF. For example, when the hybrid OETF flag is 1, the content is HDR-encoded using the hybrid OETF.

[0082] Note that the hybrid OETF flag is not necessarily required, and only the second transfer function information may be used.

[0083] Also, the hybrid descriptor is stored in at least one of the PMT (Program Map Table) defined in MPEG, the SDT (Service Description Table) defined in DVB within the DVB-SI standard, and the EIT (Event Information Table) defined in DVB within the DVB-SI standard.

[0084] The PMT indicates the PID of the TS packet storing images or audio, etc. The data playback device can extract the TS packet of the desired image or audio by obtaining the PID of the desired image or audio from the PMT.

[0085] The SDT indicates the name of the channel (service), the type of EIT transmitted on each channel, and digital copy control information, etc.

[0086] The EIT indicates information related to the program, such as the name of the program, the broadcast date and time, and the broadcast content.

[0087] When the PMT contains a hybrid descriptor, the hybrid descriptor is only assigned to the video elementary stream. However, in this case, it is necessary to control the modification of the PMT at the broadcasting station, and this modification may be difficult.

[0088] When the SDT contains a hybrid descriptor, the content of the hybrid descriptor is not frequently updated. Therefore, it is preferable when applying the content of the hybrid descriptor to the entire service.

[0089] When the EIT contains a hybrid descriptor, there is an advantage that the content of the hybrid descriptor can be changed on an event-by-event basis.

[0090] FIG. 10 is a diagram showing another configuration of the hybrid descriptor according to the present embodiment. As shown in FIG. 10, the hybrid descriptor may include, in addition to or instead of the second transfer function information, dynamic range increase information (dynamic_range_increase) and maximum average picture level information (maximum_average_picture_level).

[0091] Further, FIG. 11 is a diagram showing the configuration of an HEVC descriptor (HEVC_descriptor) according to the present embodiment. The HEVC descriptor is a descriptor at the MPEG2-TS level. As shown in FIG. 11, the reserved value of the HEVC descriptor is replaced with a hybrid coding flag (hdr_hybrid_gamma_coded_content_flag) and dynamic range increase information (dynamic_range_increase). Note that the hybrid coding flag is the same flag as the above-described hybrid OETF flag (HDR_hybrid_gamma_OETF_flag). Also, the above-described other information (second transfer function information and maximum average picture level information) may be included in the HEVC descriptor.

[0092] Similarly, a similar extension may be made to the AVC descriptor (AVC_video_descriptor).

[0093] Further, the above-described hybrid descriptor (HDR_hybrid_gamma_descriptor) and the signaling of the OETF to the video elementary stream (hybrid SEI message) may be combined. Thereby, the switching of parameters in the data playback device can be smoothly performed.

[0094] Hereinafter, this operation will be described in detail. FIG. 12 is a diagram showing the configuration of a stream and the operation of a data playback device.

[0095] The hybrid descriptor (HDR_hybrid_gamma_descriptor) including the hybrid OETF flag (HDR_hybrid_gamma_OETF_flag) is started to be transmitted slightly before the actual change. The data playback device that has received this hybrid OETF flag prepares for the change between SDR and HDR.

[0096] In addition, in order to enable the change of parameters, an EOS (End Of Sequence) indicating the end of the video sequence is inserted into the video elementary stream. Also, there are cases where a hybrid SEI message adapted to the hybrid descriptor signaled immediately before is stored and not stored in the RAP (Random Access Point) following the EOS.

[0097] The data playback device detects whether the EOS and the hybrid SEI message exist, and makes a change according to the detection result.

[0098] In the example shown in FIG. 12, when the data playback device is in a state of performing HDR operation, it acquires a hybrid descriptor including HDR_hybrid_gamma_OETF_flag = 0. Thereby, the data playback device starts preparing for the operation switching from HDR to SDR. Next, the data playback device performs the switching from HDR to SDR at the timing when it acquires EOS. Also, there is no hybrid SEI message in the SDR video elementary stream, and the data playback device does not acquire the hybrid SEI message.

[0099] Next, when the data playback device is in a state of performing SDR operation, it acquires a hybrid descriptor including HDR_hybrid_gamma_OETF_flag = 1. Thereby, the data playback device starts preparing for the operation switching from SDR to HDR. Next, the data playback device performs the switching from SDR to HDR at the timing when it acquires EOS.

[0100] Hereinafter, the operations of the data generation device 110 and the data playback device 120 based on the above will be described.

[0101] FIG. 13 is a flowchart of the operation of the data generation device 110 according to the present embodiment. The data generation device 110 generates video data that is HDR video data and is compatible with playback on a first device that does not support HDR video playback but supports SDR video playback.

[0102] First, the video signal generation unit 111 generates a video signal by converting the luminance values of the original image into code values using the second OETF (S101). Next, the encoding unit 112 generates a video elementary stream by encoding the video signal. At this time, the encoding unit 112 stores, in the VUI within the video data (video elementary stream), first transfer function information for identifying the first OETF that is referred to by the first device when the first device, which only supports SDR, plays back the video data. Also, when the second device, which supports HDR, decodes the video data, the encoding unit 112 stores, in the SEI within the video data, second transfer function information for identifying the second OETF that is referred to by the second device (S102).

[0103] Here, the VUI and SEI belong to the video coding layer. Also, the first OETF is, for example, an OETF defined by BT.709 or BT.2020, and the second OETF is, for example, the BBC Hybrid Gamma OETF.

[0104] Further, the encoding unit 112 may store, in the SEI, dynamic range increase information indicating the difference between the luminance dynamic range of the video data and the luminance dynamic range of SDR. Further, the encoding unit 112 may store, in the SEI, picture maximum average level information indicating the maximum average luminance value among the average luminance values of all the pictures included in the video sequence.

[0105] Next, the multiplexing unit 113 generates a transport stream by multiplexing the video elementary stream data. At this time, the multiplexing unit 113 stores, in the hybrid descriptor of the multiplexing layer, hybrid information (hybrid OETF flag) indicating whether the video data is HDR video data (S103).

[0106] Note that, in the example shown in FIG. 12, an example is shown in which the hybrid descriptor includes at least the hybrid OETF flag, but the hybrid descriptor may further include the second transfer function information, the dynamic range increase information, or the picture maximum average level information.

[0107] Similarly, the hybrid SEI message may include at least one of a hybrid OETF flag, second transfer function information, dynamic range increase information, and picture maximum average level information.

[0108] Also, in the above description, the hybrid OETF flag and the second transfer function information are described as individual information, but the second transfer function information may be used instead of the hybrid OETF flag. That is, the hybrid OETF flag may not be used. For example, whether the video data is HDR video data (whether the hybrid OETF is used) can be signaled depending on whether the second transfer function information is included in the video data. Or, whether the video data is HDR video data may be signaled depending on whether the hybrid OETF is indicated by the second transfer function information or whether the SDR OETF is indicated by the second transfer function information.

[0109] Note that in the above description, an example in which the hybrid OETF is indicated by the second transfer function information has been described. However, as shown in FIG. 12, when HDR video and SDR video are mixed in the video data, the SDR OETF may also be indicated by the second transfer function information for the SDR video. Thereby, in a data playback device compatible with HDR, the second transfer function information may always be referred to regardless of whether the video data is SDR or HDR. That is, the data playback device may not refer to the first transfer function information. Thereby, the processing of the data playback device can be simplified.

[0110] FIG. 14 is a flowchart of the operation of the data playback device 120 according to the present embodiment. The data playback device 120 plays back video data that is HDR video data and is compatible with playback on a first device that does not support playback of HDR video but supports playback of SDR video. Here, this video data is, for example, video data generated by the data generation device 110.

[0111] First, the demultiplexing unit 121 generates a video elementary stream by demultiplexing video data (transport stream). At this time, the demultiplexing unit 121 acquires hybrid information (e.g., hybrid OETF flag) from the hybrid descriptor of the video data (S121). Note that the demultiplexing unit 121 may further acquire at least one of the dynamic range increase information and the picture maximum average level information from the hybrid descriptor.

[0112] Next, the data playback device 120 prepares to switch between SDR playback and HDR playback based on the acquired hybrid information (S122).

[0113] Next, the decoding unit 122 generates a video signal (code value) by decoding the video elementary stream. When it is indicated by the immediately preceding hybrid OETF flag that the hybrid OETF is being used, the decoding unit 122 acquires the second transfer function information included in the hybrid SEI in the video elementary stream (S123). Note that the decoding unit 122 may further acquire at least one of the dynamic range increase information and the picture maximum average level information from the hybrid SEI.

[0114] The playback unit 123 plays back the video signal included in the video data with reference to the second OETF specified by the acquired second transfer function information (S124). Also, the playback unit 123 switches between SDR playback and HDR playback at the timing when the video sequence switches. Specifically, the playback unit 123 plays back the data after EOS in the changed format. Also, when the dynamic range increase information or the picture maximum average level information is acquired, playback is performed using this information.

[0115] In addition, when it is indicated by the immediately preceding hybrid OETF flag that the hybrid OETF is not being used, in step S123, the decoding unit 122 acquires the first transfer function information included in the VUI within the video elementary stream. In step S124, the playback unit 123 plays back the video signal included in the video data with reference to the second OETF specified by the acquired first transfer function information. As described above, when the first OETF or the second OEFT is selectively indicated by the second transfer function information, the decoding unit 122 may always acquire the second transfer function information, and the playback unit 123 may refer to the first OETF or the second OETF indicated by the second transfer function information.

[0116] As described above, in the present embodiment, in addition to the first transfer function information stored in the VUI, the second transfer function information is stored in the SEI message. Thereby, HDR encoding using a hybrid OETF such as the BBC Hybrid Gamma OETF can be realized.

[0117] Specifically, it is possible to indicate whether the content is HDR-encoded by a hybrid OETF by signaling to the multiplexing layer using a descriptor.

[0118] Also, by combining a new SEI message and a new descriptor, smooth switching between HDR and SDR by the data playback device can be realized.

[0119] Also, the first OETF may be a function defined by the following (Equation 2).

[0120]

Equation

[0121] Here, L is the luminance of the image, which is normalized to 0 ≦ L ≦ 1 at the reference white level. V is the numerical value corresponding to the electrical signal. Also, α, β, γ, δ, ρ are certain constants. As specific numerical examples, α = 4.5, β = 0.018, γ = 1.099, δ = 0.45, ρ = 0.099.

[0122] That is, as shown in (Equation 2), the first OETF may be an OETF defined by a linear term of the luminance of the video data in the first range of the luminance of the video data and defined by a power term of the luminance of the video data in a second range larger than the first range.

[0123] Furthermore, the first OETF may be a function expressed by the following (Equation 3).

[0124]

Number

[0125] Here, L is the luminance of the image, which is normalized to 0 ≦ L ≦ 1. E is the numerical value corresponding to the voltage normalized at the reference white level, and is proportional to the absolute light intensity detected in the reference camera color channel RGB. As a result, E’ becomes a non-linear signal. Also, α, β, γ, δ are certain constants. As specific numerical examples, α = 4.5, β = 0.018 (for 10-bit system) or 0.0181 (for 12-bit system), γ = 1.099 (for 10-bit system) or 1.0993 (for 12-bit system), δ = 0.45, ρ = 0.099.

[0126] Also, the second OETF may be a function defined by the following (Equation 4). In this OETF, at high luminance, the conversion function is defined by a logarithmic term.

[0127]

Number

[0128] Here, L is the luminance of the image, which is normalized by the reference white level. However, L may exceed 1. That is, this conversion function supports luminance greater than the reference white. V is a numerical value corresponding to the electrical signal. μ is the breakpoint between the gamma curve and the logarithmic curve, which determines the maximum value of L when V is 1 or less. Also, α, β, γ, δ, ρ are certain constants. As specific numerical examples, α = 4.5, β = 0.018, γ = 1.099, δ = 0.45, ρ = 0.099.

[0129] That is, as shown in (Equation 4), the second OETF may be an OETF defined by a linear term of the luminance of the video data in the third range of the luminance of the video data, a power term of the luminance of the video data in a fourth range larger than the third range, and a logarithmic term of the luminance of the video data in a fifth range larger than the fourth range.

[0130] Also, the first OETF may be a function defined by the following (Equation 5).

[0131]

Number

[0132] Here, L is the luminance of the image, which is normalized to 0 ≦ L ≦ 1 by the reference white level. V is a numerical value corresponding to the electrical signal. Also, α is a certain constant. As a specific numerical example, α = 0.5.

[0133] That is, as shown in (Equation 5), the first OETF may be an OETF defined by a power term of the luminance of the video data.

[0134] Also, the second OETF may be a function defined by the following (Equation 6). In this OETF, at high luminance, the conversion function is defined by a logarithmic term.

[0135]

Number

[0136] Also, α is a certain constant, and as a specific numerical example, α = 0.5.

[0137] That is, as shown in (Equation 6), the second OETF may be an OETF defined by a power term of the luminance of the video data in the sixth range of the luminance of the video data and defined by a logarithmic term of the luminance of the video data in a seventh range larger than the sixth range.

[0138] As described above, the data generation device (data generation method) and the data reproduction device (data reproduction method) according to one or more aspects have been described based on the embodiments. However, the present invention is not limited to these embodiments. Without departing from the spirit of the present invention, various modifications conceived by those skilled in the art applied to these embodiments or forms constructed by combining components in different embodiments may also be included within the scope of one or more aspects.

[0139] For example, in each of the above embodiments, each component may be configured by dedicated hardware such as a circuit, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

Industrial Applicability

[0140] The present invention can be applied to a data transmission device or a data reproduction device such as a BD device.

Explanation of Signs

[0141] 110 Data generation device 111 Video signal generation unit 112 Encoding unit 113 Multiplexing unit 120 Data reproduction device 121 Demultiplexing unit 122 Decoder 123 Player

Claims

1. A data generation device that generates a video elementary stream having a second luminance dynamic range wider than a first luminance dynamic range, comprising: an encoding unit that generates the video elementary stream by performing encoding compliant with a video encoding standard. The video elementary stream includes first transfer function information for specifying a first OETF (Opto-Electrical Transfer Function) referred to by a first device when the first device decodes the video elementary stream, and second transfer function information for specifying a second OETF referred to by a second device when the second device decodes the video elementary stream. Data generation device.

2. A data output device that transmits the video elementary stream according to claim 1 via a broadcast wave or a network.

3. An encoding device that generates a video elementary stream having a second luminance dynamic range wider than a first luminance dynamic range, comprising: an encoding unit that generates the video elementary stream by performing encoding compliant with a video encoding standard. The encoding unit stores, in the video elementary stream, first transfer function information for specifying a first OETF (Opto-Electrical Transfer Function) referred to by a first device when the first device decodes the video elementary stream. The encoding unit stores, in the video elementary stream, second transfer function information for specifying a second OETF referred to by a second device when the second device decodes the video elementary stream. Encoding device.

4. A decoding device that decodes a video elementary stream having a second luminance dynamic range wider than a first luminance dynamic range, comprising: a decoding unit that decodes the video elementary stream by performing decoding compliant with a video encoding standard. The video elementary stream includes first transfer function information for specifying a first OETF (Opto-Electrical Transfer Function) referred to by a first device when the first device decodes the video elementary stream, and Including second transfer function information for identifying a second OETF referenced by the second device when the second device decodes the video elementary stream Decoder device.

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