Decryption method and decryption device

Abstract

To provide a decryption method capable of displaying the right images.SOLUTION: The decryption method includes the following steps: receiving video data, audio data, and descriptor including first information that indicates the transfer function of the video data, which are transmitted from a transmitting device (S111); generating multiple pictures and second information that indicates the transfer function of the video data by decoding the video data (S113); and converting multiple pictures into input signals to be input to the display unit while controlling the conversion method applied to multiple pictures based on at least one of first information and second information (S114-S116).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a video receiving method, a video transmitting method, a video receiving device, and a video transmitting device. [Background technology]

[0002] HDR (High Dynamic Range) is attracting attention as a method that supports a luminance range with an expanded maximum luminance value in order to express bright light such as specular reflections that cannot be expressed with current TV signals in a more realistic brightness while maintaining the dark gradation of conventional images. Specifically, the luminance range method supported by conventional TV signals is called SDR (Standard Dynamic Range), which has a maximum luminance value of 100 nits, whereas HDR is expected to expand the maximum luminance value to over 1000 nits. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] ARIB STANDARD ARIB STD-B67 Version 1.0 July 3, 2015 Summary of the Invention [Problem to be solved by the invention]

[0004] In transmitting or receiving such video signals corresponding to a plurality of luminance dynamic ranges, it is desirable for the receiving device to be able to display a more appropriate image.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a video receiving method, a video transmitting method, a video receiving device, or a video transmitting device that can display appropriate video. [Means for solving the problem]

[0006] A decoding method according to one embodiment of the present invention receives video data, audio data, and a descriptor including first information indicating a transfer function of the video data transmitted from a transmitting device, decodes the video data to generate a plurality of pictures and second information indicating the transfer function of the video data, and converts the plurality of pictures into an input signal input to a display unit while controlling a conversion method applied to the plurality of pictures based on at least one of the first information and the second information.

[0007] A video decoding device according to one embodiment of the present invention comprises a receiving unit and a processor, and in operation, the processor receives via the receiving unit video data, audio data, and a descriptor including first information indicating a transfer function of the video data transmitted from a transmitting device, and decodes the video data to generate a plurality of pictures and second information indicating the transfer function of the video data, and converts the plurality of pictures into an input signal to be input to a display unit while controlling a conversion method applied to the plurality of pictures based on at least one of the first information and the second information.

[0008] Furthermore, these general or specific aspects may be realized 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 realized by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0009] The present invention can provide a video receiving method, a video transmitting method, a video receiving device, or a video transmitting device that can display appropriate images. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram of a video receiving device according to the first embodiment. [Diagram 2] FIG. 2 is a flowchart of a process performed by a display control unit according to the first embodiment. [Diagram 3]FIG. 3 is a flowchart of a video reception process according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing an operation when the transfer characteristic changes according to the first embodiment. [Diagram 5] FIG. 5 is a diagram showing an operation when the transfer characteristic changes according to the first embodiment. [Figure 6] FIG. 6 is a block diagram of the video transmitting device according to the first embodiment. [Figure 7] FIG. 7 is a flowchart of the video transmission process according to the first embodiment. [Figure 8] FIG. 8 is a diagram showing an abnormal operation when the transfer characteristic changes according to the second embodiment. [Figure 9] FIG. 9 is a block diagram of a video receiving device according to the second embodiment. [Figure 10] FIG. 10 is a flowchart of a process performed by a display control unit according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Findings on which the present invention is based) In the video coding standard ITU-T H.265|ISO / IEC 23008-2 HEVC, for example, the OETF (Optical-Electro Transfer Function) or EOTF (Electro-Optical Transfer Function) of a video signal is notified by a syntax called transfer characteristics in Video Usability Information (VUI) in the Sequence Parameter Set (SPS). By using the transfer characteristics of this SPS, it is possible to notify switching of transfer characteristics (transfer functions) with frame accuracy. The video receiving device determines a control method for the video display unit based on the transfer characteristics.

[0012] In the MPEG-2 TS (Transport Stream) standard, which is used when multiplexing and transmitting video and audio signals such as those for television broadcasting, a method is known in which the parameters and parameter-related information contained in the SPS are described in the Program-specific information (PSI) Descriptor, and information related to the operation of the video receiving device is notified at a higher layer. Regarding the transmission characteristics, by using the PSI descriptor, the video receiving device can more easily determine the control method for the video display unit. Generally, PSI is inserted into the multiplexed stream at a fixed cycle, so it is not synchronized with the frames of the video signal. Note that the MPEG-H MMT standard specifies a mechanism similar to PSI as MMT-SI.

[0013] The transfer characteristics are specified in ITU-R BT.2020 (hereinafter referred to as BT.2020), ARIB STD-B67 (hereinafter referred to as STD-B67), and SMPTE ST2084 (hereinafter referred to as ST2084), etc. STD-B67 and ST2084 can handle video signals that contain 10 to 100 times higher brightness than conventional BT.2020, which is called high dynamic range (HDR). In contrast to HDR, conventional BT.2020 and other standards are called standard dynamic range (SDR).

[0014] In HDR-compatible television broadcasts, HDR and SDR may coexist for each program or commercial, so video receiving devices must switch the display control depending on whether HDR or SDR is being displayed.

[0015] A video receiving method according to one embodiment of the present invention is a video receiving method in a video receiving device equipped with a display unit, and includes a receiving step of receiving a received signal including video data and transfer characteristic information for identifying a transfer function corresponding to the luminance dynamic range of the video data with frame accuracy, and a display step of displaying the video data while controlling the luminance dynamic range of the display unit with frame accuracy in accordance with the transfer characteristic information.

[0016] This makes it possible to control the luminance dynamic range of the display unit with frame accuracy, thereby enabling more appropriate images to be displayed.

[0017] For example, the video receiving method may further include a demultiplexing step of demultiplexing the received signal in which a video signal and an audio signal are multiplexed, and a decoding step of decoding the video signal obtained by demultiplexing to obtain the video data and the transfer characteristic information.

[0018] For example, the transfer characteristic information may be included in control information for each sequence included in the video signal.

[0019] For example, the transfer characteristic information is information for identifying, with frame accuracy, a first transfer function corresponding to a first luminance dynamic range or a second transfer function corresponding to a second dynamic range wider than the first luminance dynamic range, and in the display step, the luminance dynamic range of the display unit may be switched between the first luminance dynamic range and the second luminance dynamic range.

[0020] For example, the video receiving method may further include a determination step of determining whether the video data was correctly acquired in the receiving step, and in the display step, if it is determined in the determination step that the video data was not correctly acquired, the luminance dynamic range of the display unit may be set to the first luminance dynamic range.

[0021] This makes it possible to prevent an excessively bright image from being displayed when an error occurs.

[0022] For example, in the determining step, the determination may be made as to whether an intra-coded frame has been correctly decoded.

[0023] Moreover, a video transmission method according to one aspect of the present invention includes a generation step of generating a transmission signal including video data and transfer characteristic information for identifying, with frame accuracy, a transfer function corresponding to a luminance dynamic range of the video data, and a transmission step of transmitting the transmission signal.

[0024] This allows a video receiving device that receives a signal generated by this video transmission method to control the luminance dynamic range of the display unit with frame accuracy, thereby enabling more appropriate video display.

[0025] For example, the generating step may include an encoding step of generating a video signal by encoding the video data and the transfer characteristic information, and a multiplexing step of generating the transmission signal by multiplexing the generated video signal and an audio signal.

[0026] For example, the transfer characteristic information may be included in control information for each sequence included in the video signal.

[0027] For example, the transfer characteristic information may be information for identifying, with frame accuracy, a first transfer function corresponding to a first luminance dynamic range, or a second transfer function corresponding to a second dynamic range wider than the first luminance dynamic range.

[0028] A video receiving device according to an aspect of the present invention includes: a video data receiving unit; and a transfer characteristic information for specifying a transfer function corresponding to a luminance dynamic range of the video data with frame accuracy. and a display unit that displays the video data while controlling a luminance dynamic range with frame accuracy in accordance with the transfer characteristic information.

[0029] This allows the video receiving device to control the luminance dynamic range of the display unit with frame accuracy, thereby enabling more appropriate video to be displayed.

[0030] In addition, a video transmission device according to one embodiment of the present invention includes a generation unit that generates a transmission signal including video data and transfer characteristic information for identifying, with frame accuracy, a transfer function corresponding to the luminance dynamic range of the video data, and a transmission unit that transmits the transmission signal.

[0031] This allows the video receiving device that receives the signal generated by the video transmitting device to control the luminance dynamic range of the display unit with frame accuracy, thereby enabling more appropriate video to be displayed.

[0032] Hereinafter, the embodiment will be specifically described with reference to the drawings.

[0033] Note that the embodiments described below each show a specific example of the present invention. The numerical values, shapes, materials, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, components that are not described in an independent claim showing a superordinate concept are described as optional components.

[0034] (Embodiment 1) The video receiving device according to the present embodiment controls the luminance dynamic range of the display unit with frame accuracy by using transfer characteristic information indicating transfer characteristics with frame accuracy, thereby enabling the video receiving device to display more appropriate video.

[0035] First, the configuration of a video receiving device according to this embodiment will be described. Fig. 1 is a block diagram of a video receiving device 100 according to this embodiment. The video receiving device 100 is, for example, a television or the like, and receives a reception signal 111 transmitted by broadcast waves and displays a video based on the received reception signal 111. The video receiving device 100 includes a receiving unit 101, a demultiplexing unit 102, a video decoding unit 103, a display control unit 104, and a display unit 105.

[0036] The receiving unit 101 receives a reception signal 111. The reception signal 111 is a system stream in which a video signal and an audio signal are multiplexed.

[0037] The demultiplexer 102 generates a video signal 112, which is a video stream, by demultiplexing (system decoding) the received signal 111. The demultiplexer 102 also outputs a transfer characteristic acquired from a descriptor or the like included in the received signal 111 as first transfer characteristic information 113. That is, the first transfer characteristic information 113 is included in a multiplexing layer.

[0038] The video decoding unit 103 generates video data 114 by decoding the video signal 112. Furthermore, the video decoding unit 103 outputs the transfer characteristic acquired from the SPS as second transfer characteristic information 115. That is, the second transfer characteristic information 115 is included in a video coding layer.

[0039] The second transfer characteristic information 115 is information for specifying a transfer function (OETF or EOTF) with frame accuracy corresponding to the luminance dynamic range of the video data 114. For example, the second transfer characteristic information 115 corresponds to the first luminance dynamic range (SDR). The second transfer characteristic information 115 is information for specifying, with frame accuracy, the first transfer function obtained by the first transfer characteristic information 115 or the second transfer function corresponding to a second dynamic range (HDR) wider than the first luminance dynamic range. That is, the second transfer characteristic information 115 indicates whether the video data 114 is SDR or HDR. In addition, when there are multiple formats of HDR, the second transfer characteristic information 115 may indicate which format of HDR it is. That is, the second transfer characteristic information 115 indicates the luminance dynamic range of the video data 114, and indicates, for example, any one of multiple predetermined luminance dynamic ranges.

[0040] Moreover, the SPS is control information included in the video signal 112 in sequence units (multiple frames).

[0041] The display control unit 104 generates control information 116 for controlling the display unit 105 in accordance with the first transfer characteristic information 113 and the second transfer characteristic information 115 .

[0042] The display unit 105 displays the video data 114 while controlling the luminance dynamic range with frame accuracy in accordance with the control information 116 (i.e., the first transfer characteristic information 113 and the second transfer characteristic information 115). The display unit 105 includes an image characteristic conversion unit 106 and a display device 107.

[0043] The image characteristic conversion unit 106 converts the image data 114 in accordance with the control information 116 to generate an input signal 117. Specifically, the image characteristic conversion unit 106 converts the image data 114 into the input signal 117 by using a transfer function indicated by the first transfer characteristic information 113 or the second transfer characteristic information 115.

[0044] Display device 107 is, for example, a liquid crystal panel, and changes the luminance dynamic range of the image to be displayed in accordance with control information 116. For example, when display device 107 is a liquid crystal panel, display device 107 changes the maximum luminance of the backlight.

[0045] Next, the operation of the video receiving device 100 will be described. Although Fig. 1 shows a configuration using both the first transfer characteristic information 113 and the second transfer characteristic information 115, it is sufficient to use at least the second transfer characteristic information 115. Hereinafter, the control using the second transfer characteristic information 115 will be described in detail.

[0046] Fig. 2 is a flowchart of a display control process by the display control unit 104. Note that the process shown in Fig. 2 is performed on a frame-by-frame basis or every time the second transfer characteristic information 115 is changed.

[0047] First, the display control unit 104 determines whether the second transfer characteristic information 115 indicates SDR or HDR (S101).

[0048] When the second transfer characteristic information 115 indicates HDR (Yes in S101), the display control unit 104 outputs control information 116 for HDR display (S102). As a result, the display unit 105 displays the image in a luminance dynamic range corresponding to HDR.

[0049] On the other hand, if the second transfer characteristic information 115 indicates SDR (No in S101), the display control unit 104 outputs control information 116 for displaying SDR (S103). This causes the display unit 105 to display an image with a luminance dynamic range corresponding to SDR.

[0050] In this way, by switching the control information 116 in response to the second transfer characteristic information 115 notified with frame accuracy, it is possible to synchronize the switching of the transfer characteristic and the control of the display unit 105 with frame accuracy.

[0051] In addition, when there are multiple HDR methods (for example, STD-B67 and ST2084), identification information of the HDR method may be included in the control information 116 for HDR display. This allows the display unit 105 to display an image with a luminance dynamic range of the corresponding method.

[0052] 3 is a flowchart of the video reception process by the video receiving device 100. First, the receiving unit 101 receives the received signal 111 (S111). Next, the demultiplexing unit 102 demultiplexes the received signal 111 to generate a video signal 112 (S112). Next, the video decoding unit 103 decodes the video signal 112 to generate video data 114, and acquires second transfer characteristic information 115 (S113).

[0053] Next, the display control unit 104 controls the luminance dynamic range of the display unit 105 according to the second transfer characteristic information 115. Specifically, the display control unit 104 determines whether each frame is HDR or SDR with frame accuracy based on the second transfer characteristic information 115 (S114). If it is HDR (Yes in S114), the display unit 105 displays the image with the luminance dynamic range of HDR (S115). If it is SDR (No in S114), the display unit 105 displays the image with the luminance dynamic range of SDR (S116).

[0054] Fig. 4 is a diagram showing a state when switching from an SDR program to an HDR program. Fig. 5 is a diagram showing a state when switching from an HDR program to an SDR program. As shown in Fig. 4 and Fig. 5, the above processing makes it possible to appropriately switch between SDR and HDR with frame accuracy.

[0055] Hereinafter, a description will be given of a video transmitting device 200 that generates a transmission signal 212 corresponding to the above-mentioned received signal 111. Fig. 6 is a block diagram of the video transmitting device 200 according to the present embodiment. The video transmitting device 200 shown in Fig. 6 includes a generating unit 201 and a transmitting unit 202.

[0056] The generating unit 201 generates a transmission signal 212 including video data and second transfer characteristic information for specifying a transfer function corresponding to the luminance dynamic range of the video data with frame accuracy. The generating unit 201 includes a video encoding unit 203 and a multiplexing unit 204.

[0057] 7 is a flowchart of a video transmission process by the video transmitting device 200. First, the video encoding unit 203 generates a video signal 211 by encoding video data and second transfer characteristic information (S201). This second transfer characteristic information corresponds to the above-mentioned second transfer characteristic information 115, and is information for specifying, with frame accuracy, a first transfer function corresponding to a first luminance dynamic range (for example, SDR) or a second transfer function corresponding to a second dynamic range (for example, HDR) wider than the first luminance dynamic range. In addition, the second transfer characteristic information is stored in an SPS included in the video signal 211.

[0058] Next, the multiplexing unit 204 multiplexes the encoded video signal 211 and audio signal to generate the transmission signal 212 (S202). Next, the transmitting unit 202 transmits the generated transmission signal 212 (S203).

[0059] In this way, the video transmitting device 200 generates the transmission signal 212 including the second transfer characteristic information for identifying the transfer function with frame accuracy. This allows the video receiving device receiving the transmission signal 212 to control the luminance dynamic range of the display unit with frame accuracy, thereby enabling more appropriate video to be displayed.

[0060] (Embodiment 2) In TV broadcasting, errors may occur depending on the radio wave conditions of terrestrial or satellite broadcasts. Fig. 8 is a diagram showing a state in which a reception error occurs due to radio interference or the like. As shown in Fig. 8, when switching from SDR to HDR, it is assumed that after the video receiving device acquires the second transfer characteristic information 115 in the SPS, a video stream is lost due to radio interference or the like, and the first frame of HDR cannot be acquired. In this case, the video decoding unit 103 continues to display the previous frame to conceal the error. In other words, frames of the SDR program are repeatedly displayed.

[0061] In this case, when this frame is referenced by subsequent frames, abnormal images that contain images of past programs are displayed as subsequent images.

[0062] In addition, immediately after the switch, the brightness dynamic range of the display is set to HDR, so frames from SDR programs are displayed in the HDR brightness dynamic range, resulting in a problem of images being displayed at a higher brightness than originally intended.

[0063] In this embodiment, a video receiving device that addresses this problem will be described. Fig. 9 is a block diagram of a video receiving device 100A according to this embodiment. The video receiving device 100A shown in Fig. 9 further includes an abnormality detection unit 108 and a message superimposition unit 109 in a display unit 105A in addition to the components of the video receiving device 100 shown in Fig. 1. Also, a function is added to the display control unit 104A.

[0064] The abnormality detection unit 108 judges whether the video data 114 (video signal 112) has been correctly acquired. Specifically, the abnormality detection unit 108 detects packet loss based on the sequence number of the packet, and determines whether all of the frame data has been acquired (normal) or whether only a part of the frame data has been acquired (abnormal) by analyzing the payload of the packet and acquiring the starting position of the frame data. The abnormality detection unit 108 also outputs abnormality notification information 118 indicating the judgment result to the display control unit 104A. In other words, the occurrence of an abnormality or information for identifying the frame in which the abnormality has occurred is notified to the display control unit 104A.

[0065] The display control unit 104A generates control information 116 and a message 119 in response to 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 occurs, the display control unit 104A generates a message 119 indicating that an abnormality occurs, and also generates control information 116 for SDR display.

[0066] The message superimposing unit 109 generates an input signal 120 by superimposing the message 119 on the video data (input signal 117) in accordance with the control information 116 and the message 119, and outputs the generated input signal 120 to the display device 107. In this way, a message such as "An error has occurred" is displayed on the display device 107, thereby informing the viewer that the problem is not due to a malfunction of the equipment.

[0067] 10 is a flowchart of the display control process by the display control unit 104A. First, the display control unit 104A determines whether the second transfer characteristic information 115 has been updated (S121). If the second transfer characteristic information 115 has been updated (Yes in S121), the display control unit 104A starts determining whether to switch the display control.

[0068] First, the display control unit 104A judges whether the video data has been correctly acquired. Specifically, the display control unit 104A judges whether the intra-coded frame has been correctly decoded based on the abnormality notification information 118 (S122). If the intra-coded frame has not been correctly decoded (No in S122), the display control unit 104A outputs control information 116 for SDR display (S123). This causes the display unit 105 to display the video in a luminance dynamic range corresponding to SDR. In other words, the display control unit 104A outputs the control information 116 for SDR display (S123). If it is determined that the data has not been acquired correctly, the luminance dynamic range of the display unit 105 is set to SDR (first luminance dynamic range).

[0069] If an error occurs during switching, the displayed frame may contain pixels from the frame before switching. In response to this, in this embodiment, by setting the display control for SDR display in such a case, it is possible to prevent frames of an SDR program from being displayed with the high brightness setting of HDR.

[0070] Furthermore, when an intra-coded frame that guarantees jump-in playback, such as IDR or CRA of HEVC, is normally decoded (Yes in S122), the display control is switched in the same manner as in the first embodiment. That is, the display control unit 104A determines whether the updated second transfer characteristic information 115 indicates SDR or HDR (S124). When the second transfer characteristic information 115 indicates HDR (Yes in S124), the display control unit 104A outputs control information 116 for HDR display (S125). On the other hand, when the second transfer characteristic information 115 indicates SDR (No in S124), the display control unit 104A outputs control information 116 for SDR display (S126).

[0071] In this way, the video receiving device 100A according to the present embodiment displays video in the luminance dynamic range of SDR when an error occurs, thereby making it possible to prevent an excessively bright video from being displayed when an error occurs.

[0072] Although the video receiving device and the video transmitting device according to the embodiment of the present invention have been described above, the present invention is not limited to this embodiment.

[0073] Furthermore, each processing unit included in the video receiving device and the video transmitting device according to the above-mentioned embodiments is typically realized as an LSI, which is an integrated circuit. These may be individually implemented as single chips, or some or all of them may be included in a single chip.

[0074] The integrated circuit is not limited to an LSI, but may be realized by a dedicated circuit or a general-purpose processor. A field programmable gate array (FPGA) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connections and settings of the circuit cells inside the LSI may also be used.

[0075] In each of the above embodiments, each component may be implemented by dedicated hardware or by executing a software program suitable for each component. Each component may be implemented by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0076] Furthermore, the present invention may be realized as a video receiving method or a video transmitting method executed by a video receiving device or a video transmitting device.

[0077] In addition, the division of functional blocks in the block diagram is an example, and multiple functional blocks may be realized as one functional block, one functional block may be divided into multiple blocks, or some functions may be transferred to another functional block. Furthermore, the functions of multiple functional blocks having similar functions may be processed in parallel or in a time-sharing manner by a single piece of hardware or software.

[0078] The order in which the steps are executed in the flowchart is merely an example for specifically explaining the present invention, and the steps may be executed in an order other than the above. Some of the steps may be executed simultaneously (in parallel) with other steps.

[0079] Although the video receiving device and the video transmitting device according to one or more aspects have been described based on the embodiments, the present invention is not limited to these embodiments. As long as they do not deviate from the spirit of the present invention, various modifications conceived by those skilled in the art to the present embodiments and configurations constructed by combining components of different embodiments may also be included within the scope of one or more aspects. [Industrial Applicability]

[0080] The present invention can be applied to video receiving devices and video transmitting devices such as TVs. [Explanation of symbols]

[0081] 100, 100A Video receiving device 101 Receiving unit 102 Demultiplexer 103 Video Decoding Unit 104, 104A Display control unit 105, 105A display section 106 Video characteristics conversion section 107 Display Devices 108 Anomaly detection unit 109 Message Overlay Unit 111 Received signal 112, 211 Video signal 113 First transmission characteristic information 114 Video Data 115 Second transmission characteristic information 116 Control Information 117, 120 Input signal 118 Abnormality notification information 119 Messages 200 Video transmission device 201 Generation part 202 Transmitter 203 Video Encoding Unit 204 Multiplexer 212 Transmitted Signal

Claims

1. receiving video data, audio data, and a descriptor including first information indicating a transfer function of the video data, the video data and the audio data being transmitted from a transmitting device; Decoding the video data to generate a plurality of pictures and second information indicative of the transfer function of the video data; The plurality of pictures are converted into an input signal to be input to a display unit while controlling a conversion method applied to the plurality of pictures based on at least one of the first information and the second information. Decryption method.

2. A receiving unit; a processor; The processor, in operation, receiving, via the receiving unit, video data, audio data, and a descriptor including first information indicating a transfer function of the video data, the video data and the audio data being transmitted from a transmitting device; Decoding the video data to generate a plurality of pictures and second information indicative of the transfer function of the video data; The plurality of pictures are converted into an input signal to be input to a display unit while controlling a conversion method applied to the plurality of pictures based on at least one of the first information and the second information. Decryption device.

Images