JP6546981B2 - Broadcast signal transmitting apparatus and transmitting method of broadcast signal transmitting apparatus - Google Patents

Description

  The present embodiment relates to, for example, a broadcast signal transmission apparatus and a transmission method of the broadcast signal transmission apparatus which expand the color gamut of an image signal transmitted from a broadcast facility according to the specification of a display panel.

  In the current television broadcasting according to ARIB standards, the color gamut used in transmission of image signals is defined by BT.709. The color gamut defined by BT.709 is narrower than the color gamut of the natural world. Therefore, in the current equipment, an image having a color gamut of the natural world is photographed and transmitted by being shrunk to the color gamut of BT.709.

  By the way, advances in television display panels have made it possible to display a wider color gamut than BT.709. In this case, if display is performed according to the BT.709 standard, even a display panel having a wide color gamut is displayed in the color gamut of BT.709. Taking this point into consideration, among signals reduced to the color gamut of BT.709, signals close to the color gamut limit are estimated to be signals that are out of the range of BT.709, etc. It is also possible to estimate and restore (color gamut expansion) a signal of a color gamut state wider than that of BT.709 before the signal of .709 is reduced to BT.709. Even an image signal transmitted by BT. 709 can be displayed in a wider color range than BT. 709 within the displayable range of the display panel, and a colorful image can be enjoyed.

  On the other hand, in the next-generation broadcasting standard considering 4K broadcasting, there is a possibility of adopting BT.2020 which can express a color gamut wider than BT.709. In the case of video content produced with equipment capable of shooting in a wide color gamut, the above-mentioned display panel is capable of displaying an image of a color gamut wider than BT.709 if an image signal is transmitted using the BT.2020 standard. It is possible to enjoy a colorful image with a wide color gamut without such color gamut expansion processing.

  It is specified in ARIB standard B32 so that whether it transmits in the color gamut of BT. 709 or in the color gamut of BT. 2020 can be indicated by the parameter "transfer_characteristics" in the VUI "of the video stream. (See “ARIB Standard Document STD-B32_2.8 version 5.1.2.3 (2) VUI middle level”).

  However, there are a large number of video contents represented by BT. 709, which were shot in the past when there was no equipment capable of shooting and recording in a wide color gamut such as BT. 2020. The BT.2020 standard covers the color gamut of BT.709, so it can be transmitted according to the BT.2020 standard. In this case, only part of the color gamut that can be expressed by the BT. 2020 standard is used for transmission. If this is the case, a colorful image can be enjoyed by displaying using the above-described color gamut expansion technology.

  However, the image signal transmitted by BT.2020 is a transmission in which only a part of the color gamut that can be expressed by the BT.2020 standard is used, or a color gamut beyond the BT.709 range is used Since there is no means for determining whether the signal is being used, it can not be determined whether or not the color gamut expansion processing should be performed. As a result, while high-definition broadcasts that require transmission by BT. 709 can be subjected to color gamut expansion processing and can enjoy colorful images, 4K broadcasts that adopt the BT. 2020 standard In this case, the content captured in BT.709 can not restore the color gamut, and the high-definition broadcast looks more vivid than the 4K broadcast, which should have adopted the wider color gamut standard. There is a possibility that it will be.

JP, 2006-180477, A

  As described above, in the image processing apparatus in the conventional high-vision broadcasting system, color gamut expansion processing can be performed in high-vision broadcasting where transmission by the current BT. 709 is defined, and a colorful image can be enjoyed In the case of 4K broadcasting where the BT.2020 standard is adopted, the content photographed in BT.709 can not restore the color gamut, but adopts a wider color gamut standard. There is a possibility that the high-definition broadcast will look brighter than the supposed 4K broadcast.

  The present embodiment has been made in view of the above problems, is the image signal transmitted by BT. 2020 being a transmission in which only a part of the color gamut that can be expressed by the BT. 2020 standard is used, or BT It can be judged whether it is a signal that is used up to the color gamut beyond the range of .709, and it is judged whether or not the color gamut expansion processing should be performed, and 4K broadcast of BT. 2020 standard is adopted. In this case, it is an object of the present invention to provide a broadcast signal transmitting apparatus and a transmission method of the broadcast signal transmitting apparatus capable of restoring the color gamut of content captured in BT.709.

According to the broadcast signal transmitting apparatus of one embodiment, a video encoder that outputs a video stream including a compressed and encoded video signal, and an information processing that generates a PMT to be referred to for decoding and displaying the video signal. What is claimed is: 1. A broadcast signal transmission apparatus comprising: an apparatus; a multiplexing apparatus for multiplexing the video stream and the PMT; and a modulation apparatus for modulating an output of the multiplexing apparatus to output a broadcast signal.
The information processing apparatus describes related color gamut data associated with a color gamut specified by transfer characteristics in the video stream in the PMT, and the related color gamut data before SL gamut, characterized in that it presents a to plurality of types exists.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows schematic structure of the digital television (following, TV) broadcast system to which embodiment is applied. The block diagram which shows schematic structure of the broadcast installation shown in FIG. FIG. 2 is a block diagram showing a schematic configuration of the broadcast receiving apparatus shown in FIG. 1; The color gamut chart shown compared with the specification of T.709 and the specification of BT.2020 about the color gamut distribution of the display panel used for the broadcast receiving apparatus shown in FIG. FIG. 2 is a view showing an example in which an imaging camera shoots in a color gamut of BT. 709 in the system shown in FIG. 1; In the system shown in FIG. 1, as an example in which the imaging camera shoots in the color gamut of BT. 709, when the display panel can display a wider color gamut than BT. 709, the image processing circuit of the receiving apparatus performs color gamut of the display panel. The figure which shows the example which performs color gamut expansion according to. In the system shown in FIG. 1, the color gamut adjustment in the case where the transmission path can transmit in a wide color gamut such as BT.2020 and the camera can shoot in a wide color gamut such as BT.2020. The figure which shows the example which the range of a color gamut can reproduce correctly the color gamut image | photographed with the camera. In the system shown in FIG. 1, when a content having only the color gamut of BT. 709 taken with a high-vision camera is sent through the transmission path of BT. Figure. In the system shown in FIG. 1, even if the transmission path is in the color gamut of BT. 2020 and a signal using only the color gamut of BT. 709 is passed through, the receiving device performs color gamut expansion processing to represent the display panel. The figure which shows the example displayed using all the possible color gamuts. The system shown in FIG. 1 WHEREIN: The figure which shows the data structure of PMT. FIG. 2 shows the structure of a video decode control descriptor in the system shown in FIG. 1; FIG. 2 shows the structure of the original gamut descriptor in the system shown in FIG. FIG. 2 is a diagram showing an example of putting a flag in a video stream in the system shown in FIG. 1;

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of a digital television (hereinafter referred to as TV) broadcast system to which the embodiment is applied. This system is comprised of the broadcast equipment 100 of the configuration shown in FIG. 2 and the broadcast reception apparatus 200 shown in FIG. 3, both of which are connected by a transmission line. The transmission path is not limited to a wireless transmission path by broadcast waves, but also includes a wired transmission path by cable.

  The broadcast facility 100 shown in FIG. 2 includes an imaging camera 101. The video content photographed by the imaging camera 101 is recorded in the video recording and reproducing apparatus 102. The video content recorded in the video recording and reproducing apparatus 102 is subjected to editing processing such as addition of an audio signal by the editing apparatus 103, and is re-recorded on the present apparatus 102 as program content. The program content read from the video recording and reproducing apparatus 102 along the program organization is sent to the audio encoder 104, the video encoder 105, the subtitle information processing apparatus 106, the program information processing apparatus 107, and the descriptor inserting apparatus 108. The audio encoder 104 and the video encoder 105 respectively compress and encode audio data (audio) and video data (video) of program content. The subtitle information processing apparatus 106 generates subtitle information to be inserted into the video of the program content in real time. The program information processing apparatus 107 generates various information for presenting effects of program content and introducing program content by SI / PSI (Service Information / Program Specific Information). The descriptor insertion device 108 sends a descriptor relating to the color gamut to the program information processing device 107 at the time of reproduction of the program content, and incorporates it into SI / PSI as one of the program information. The audio data, the video data, the subtitle data, and the program information (including the descriptor) obtained by the audio encoder 104, the video encoder 105, the subtitle information processing apparatus 106, and the program information processing apparatus 107 are multiplexed by the multiplexing apparatus 109 to be broadcast program It becomes data. The broadcast program data is modulated for transmission by the modulation device 110 and output to the transmission path as a broadcast signal. The output of the imaging camera 101 may be sent directly to the video encoder 105 when broadcasting in real time.

  The broadcast receiving apparatus 200 shown in FIG. 3 includes a tuner 201 that receives a broadcast signal transmitted from the broadcast facility 100 through a transmission path by a channel selection operation. The broadcast signal is demodulated by the demodulator 202, and then demultiplexed into audio data, video data, subtitle information, SI / PSI multiplexed in the broadcast signal by the demultiplexer 203, and the audio decoder 204 and the video decoder 205, respectively. , Subtitle information decoder 206 and SI / PSI processor 207. The audio decoder 204, the video decoder 205, the subtitle information decoder 206, and the SI / PSI processing unit 207 extract an audio signal, a video signal, subtitle information, and SI / PSI information from input data, respectively, and restore the original format. The output of is sent to the screen combining device 209 to be combined on the screen, and is appropriately image processed by the image processing device 210 and displayed on the display panel 211.

  Here, the SI / PSI information obtained by the SI / PSI processor 207 is sent to the descriptor separation device 208. The descriptor separation device 208 separates the descriptor including the original color gamut information to be described from the input SI / PSI information, determines the color gamut information, and sends it to the image processing device 210. Thereby, the image processing apparatus 210 adjusts the color gamut of the input image based on the color gamut information.

  In the system according to the above configuration, color gamut control processing will be described with reference to FIGS. 4 to 13.

  FIG. 4 is a chromaticity diagram, a indicates the color gamut of the display panel 211, b indicates the color gamut defined by BT. 2020, and c indicates the color gamut defined by BT. 709. Here, with the performance of the liquid crystal display panel in the early stage of sale, it was not possible to display a wide color gamut, and it was possible to display only a color gamut comparable to BT.709. However, recently, it has become possible to display in a color gamut as shown by a wider than c, for example.

  In the above-described system, in the case of live broadcast or the like, an image captured by the imaging camera 101 is compressed and encoded by the audio encoder 104 or the video encoder 105. In the case of a recorded program, the video signal and the audio signal obtained by the imaging camera 101 are temporarily recorded in the video recording / reproducing apparatus 102 together with the color gamut information (for example, BT.709 and BT.2020 etc.) of the signal. Is edited by the editing apparatus 103 and re-recorded, reproduced at the video recording / reproducing apparatus 102 at the broadcast time, and compressed and encoded by the audio encoder 104 and the video encoder 105.

  Here, the video encoder 105 encodes the color gamut indicated by the color signal of the video signal as BT. 2020. The parameter transfer_characteristics in the encoded stream indicates BT.2020. The color gamut standards include those defined by BT.601, BT.709, sRGB, BT.2020, Adobe RGB, and DCI (Digital Cinema Initiatives).

  When the color gamut of the imaging camera 101 is not BT. 2020, a descriptor indicating the original color gamut is set by the descriptor insertion device 108, and is put in PMT (Program Map Table) of SI / PSI information. The data structure of PMT is shown in FIG. In this data structure, the descriptor is described where the description of the Descriptor exists.

  That is, in the present embodiment, “on the transmission side, the image coding / transmission apparatus is provided with multiplexing means for multiplexing the original color gamut information of the content separately from the transmission color gamut information. The original color gamut information is separated from the received signal, and the color gamut expansion processing is performed when the color gamut of the original content is narrower than the color gamut of the display panel.

Here, “multiplexes and transmits the original color gamut information of the content. It is switched whether to execute the color gamut restoration processing according to the original color gamut information.” Is a new way of thinking before. .
Therefore, the place where the original color gamut information is multiplexed is described in the video decode control descriptor of the PMT (specifically, “ARIB standard document TR-B14 version 5.3 (second volume) third part table operation Details, see 30.3.3.6 Video Decode Control Descriptor ").

Here is 2 bit reserved_future_use. This is currently operating at '11'. This is defined, for example, as follows.
11: The original content has the same color gamut as the color gamut defined in transfer_characteristics in the video stream.
10: The original content has the same color gamut as that of BT.709.
01: Original content has the same color gamut as that defined in DCI (Digital Cinema Initiative).

  Also, the place where the original color gamut information is multiplexed may be described by adding a new descriptor to the PMT descriptor.

Also, as an encoding parameter in the video stream, a parameter of “original content gamut” is added.
11: The original content has the same color gamut as the color gamut defined in transfer_characteristics in the video stream.
10: The original content has the same color gamut as that of BT.709.
01: Original content has the same color gamut as that defined in DCI (Digital Cinema Initiative).

Also, there is a method of describing the original color gamut in a video decode control descriptor. FIG. 11 shows the data structure of the video decode control descriptor. In this data structure, reserved_future_use has 2 bits. Here, a 2-bit code defined as follows is described.
11: The original content has the same color gamut as the color gamut defined in transfer_characteristics in the video stream.
10: The original content has the same color gamut as that of BT.709.
01: Original content has the same color gamut as that defined in DCI (Digital Cinema Initiative).

  Here, information related to a program is called SI / PSI in the MPEG or ARIB standard, and is multiplexed and sent out by the multiplexer 109 together with the compression-coded video audio signal.

  5 to 9 show the color gamut of the natural world → the color gamut of the camera → the color gamut of the editing device → the color gamut of the transmission path → the color gamut of the receiver → the flow of each process of the color gamut of the display panel (horizontal axis) In the figure, an example of how the color gamut (vertical axis: for example, the value along the vector of the color gamut in FIG. 3) changes is shown.

(Example of FIG. 5)
In normal high-definition broadcasts, signals in the wide color gamut of the natural world are transmitted by being shrunk to the color gamut of BT.709. This figure shows an example in which the camera 101 shoots in the color gamut of BT.709. When the color gamut of the camera 101 is wide and the color gamut is narrowed by the editing apparatus 103, it is as shown by a dotted line. Then, if the display panel 211 can only display the color gamut of BT.709, the viewer will enjoy the color gamut of BT.709.

(Example of FIG. 6)
A signal of wide color gamut in the natural world is transmitted by being shrunk to the color gamut of BT.709. This figure shows an example in which the camera 101 shoots in the color gamut of BT.709. Then, if the display panel 211 can display a color gamut wider than BT. 709, the image processing apparatus 210 of the receiving apparatus 200 performs color gamut expansion in accordance with the color gamut of the display panel 211. Thus, the viewer can enjoy the color gamut of the display panel 211.

(Example of FIG. 7)
When the transmission path can transmit in a wide color gamut such as BT.2020, if the camera 101 can capture an image in a wide color gamut such as BT.2020, the signal is transmitted as it is, and the image processing apparatus 210 of the receiving apparatus 200 displays the display panel. The color gamut is adjusted in accordance with the color gamut 211, and if the color gamut of the display panel 211 is narrower than BT. 2020, processing for reducing the color gamut is performed and displayed. Thus, in the range of the color gamut of the display panel 211, the color gamut photographed by the camera 101 can be correctly reproduced.

(Example of FIG. 8)
If you try to edit content taken with a camera in the high-vision era with the editing device 103 in the color gamut of BT.2020 or transmit it through the transmission path in the color gamut of BT.2020, the device can handle a wide color gamut. But only a part of it is used. In the receiving apparatus 200, as long as it is sent through the transmission path of BT. 2020, it must be assumed that a signal of that color gamut will come. For this reason, if color gamut expansion processing is performed, a signal may overflow if a color gamut signal exceeding BT. 709 is transmitted, so even a signal having only the color gamut of BT. 709. Even then, it will be displayed as it is. In the range of BT.709, color display is correctly performed.

(Example of FIG. 9)
Even if the transmission path is in the color gamut of BT. 2020 and a signal using only the color gamut of BT. 709 is passed through, it is clearly notified to the receiving device 200 by additional information such as SI / PSI. For example, the receiving device 200 can perform color gamut expansion processing by the image processing device 210 and display using all the color gamuts that can be expressed by the display panel 211.

Another way to indicate the original gamut is to augment and describe a single new descriptor. FIG. 12 shows the structure of the original gamut descriptor. A code having the following definition is described in 3 bits of original_color_gamut in FIG.
111: The original content has the same color gamut as that defined in transfer_characteristics in the video stream.
100: Original content has the same color gamut as that of adobe RGB.
011: The original content has the same color gamut as that of BT.601.
010: The original content has the same color gamut as that of BT.709.
001: Original content has the same color gamut as that defined in DCI (Digital Cinema Initiative).
The placement location of the descriptor does not have to be limited within PSI as in PMT, and may be placed in SI such as EIT (program guide).

Also, if the color gamut of the camera 101 is not BT. 2020, some bit parameter of original_vcolor_gamut may be added and transmitted separately from the parameter of transfer_characteristics in the encoded stream. For example, 4 bits
1111: The original content has the same color gamut as that defined in transfer_characteristics in the video stream.
0100: The original content has the same color gamut as that of adobe RGB.
0011: The original content has the same color gamut as that of BT.601.
0010: The original content has the same color gamut as that of BT.709.
0001: Original content has the same color gamut as that defined in DCI (Digital Cinema Initiative).

  Another way to indicate the original color gamut is to put a flag rather than a parameter in the encoded video stream. FIG. 13 shows a structure in which the flag of the original gamut descriptor is added to transfer_characteristics.

As described above, according to the configuration of the above embodiment, the original color gamut information of the content is separated from the received signal, and the color gamut expansion processing is performed when the color gamut of the original content is narrower than the color gamut of the display panel. carry out. As a result, even if content in a narrow color gamut is transmitted using a data format in a wide color gamut, it is possible to enjoy a colorful image by performing color gamut expansion processing on the receiving device side. Even if content of a wide color gamut is transmitted using a data format of a wide color gamut, correct color can be displayed by not performing color gamut expansion processing on the receiving device side. Thus, regardless of whether the color gamut of the content is BT. 709 or BT. 2020, it is possible to enjoy colorful display by effectively using the color gamut of the display panel.
That is, when an image signal having a color gamut of BT. 709 or an image signal having a color gamut of BT. 2020 is transmitted in a wide color gamut format such as BT. Since the color gamut information of is multiplexed and the data to be transmitted is detected and judged, if the original color gamut is BT. 709, color gamut restoration processing can be added and enjoy a colorful image In the case of BT. 2020, the original color gamut can be displayed without color gamut restoration processing.

  The present embodiment is not limited to the above embodiment as it is, and at the implementation stage, the constituent elements can be modified and embodied without departing from the scope of the invention. In addition, various inventions can be formed by appropriate combinations of a plurality of constituent elements disclosed in the above embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components in different embodiments may be combined as appropriate.

  DESCRIPTION OF SYMBOLS 100 ... Broadcast installation, 101 ... Imaging camera, 102 ... Video recording and reproducing apparatus, 103 ... Editing apparatus, 104 ... Audio encoder, 105 ... Video encoder, 106 ... Subtitle information processing apparatus, 107 ... Program information processing apparatus, 108 ... Descriptor insertion Apparatus 200 Broadcast receiving apparatus 201 Tuner 202 Demodulation apparatus 203 Multiplexing apparatus 204 Audio decoder 205 Video decoder 206 Subtitle information decoder 207 SI / PSI processor 208 Descriptor Separation device, 209 ... screen combining device, 210 ... screen combining device, 211 ... display panel

Claims (2)

A video encoder that outputs a video stream including a compression encoded video signal;
An information processing apparatus for generating a PMT to be referred to for decoding and displaying the video signal;
A multiplexer for multiplexing the video stream and the PMT;
A modulation device that modulates the output of the multiplexing device and outputs a broadcast signal;
In a broadcast signal transmitter having
The information processing apparatus is
It describes a related gamut data associated with the color gamut specified by the video stream during the transfer character Ryi scan Kinetics (transfer_characteristics) in the PMT, and multiple previous SL gamut by the relevant color gamut data 1. A broadcast signal transmitter characterized in that the kind is present. A video encoder outputs a video stream including a video signal compressed and encoded, the information processor generates a PMT to be referred to for decoding and displaying the video signal, and a multiplexer outputs the video stream and the PMT. in a multiplexed transmission method of the broadcast signal transmitting apparatus for outputting a broadcast signal by modulating the output that the multiplexed by modulator,
The information processing apparatus describes related color gamut data associated with a color gamut specified by transfer characteristics in the video stream in the PMT, and the related color gamut data transmitting method of the broadcast signal transmitting apparatus before Symbol gamut indicates to multiple types present, it is characterized.

Images