JP6677230B2 - Video encoding device, video decoding device, video system, video encoding method, and video encoding program - Google Patents

Description

  The present invention relates to a video encoding device, a video decoding device, a video system, a video encoding method, and a video encoding program based on an encoding method of dividing a video screen and then compressing the divided video screen.

  In response to a demand for higher definition of a video, a full HD (High Definition) video content of 1920 in the horizontal direction × 1080 (pixels) in the vertical direction is supplied. Also, test broadcasting and commercial broadcasting of high-definition video (hereinafter, referred to as 4K) of 3840 × 2160 (pixels) in the horizontal direction have been started. Further, commercial broadcasting of high-definition video (hereinafter referred to as 8K) of 7680 horizontal directions × 4320 (pixels) vertical direction is planned.

  In a video content distribution system, in general, a video signal is encoded based on the H.264 / AVC (Advanced Video Coding) standard or HEVC (High Efficiency Video Coding) standard on the transmission side, and is decoded through a decoding process on the reception side. The signal is reproduced, but in the case of 8K, since the number of pixels is large, the processing load in the encoding process and the decoding process increases.

  As a method for reducing the processing load in the case of 8K, for example, there is a screen quadruple coding using slices described in Non-Patent Document 1 (see FIG. 11). As shown in FIG. 12, in Non-Patent Document 1, in a block near a slice boundary, when inter-prediction is performed, when a screen quadruple encoding is used for a motion vector for motion compensation (MC), , A constraint that the vertical component (vertical direction) of the slice is 128 pixels or less. Note that there is no restriction on the motion vector range in the vertical direction across the slice boundary (hereinafter, referred to as motion vector restriction) for blocks not belonging to the vicinity of the slice boundary.

  In 4K and 8K, not only standard dynamic range (SDR) video signals but also ARIB STD-B67 standard high dynamic range (HDR) video signals .), And the use of video signals such as the SMPTE ST.2084 HDR Perceptual Quantizer (hereinafter referred to as PQ). Therefore, switching between SDR and HDR also needs to be considered.

ARIB (Association of Radio Industries and Businesses) standard STD-B32 version 3.0 July 31, 2014 Radio Industry Association

  When there is a motion vector restriction, when encoding a scene in which an object on the screen or the entire screen moves fast in the vertical direction, an optimal motion vector may not be selected at a slice boundary. As a result, there is a possibility that local image quality degradation will occur. The degree of deterioration increases as the M value increases during fast movement. The M value is a reference picture interval. The “optimal motion vector” means an original (regular) motion vector selected by a predictor that performs an inter-screen prediction (inter prediction) process in the video encoding device.

  FIG. 14 illustrates the intervals between reference pictures when M = 4 and M = 8. In general, when the M value is small, the distance between frames is small, so that the value of the motion vector tends to be small. However, particularly in a stationary scene, the number of layers in the time direction is reduced, so that the code amount distribution according to the layer (layer) is restricted, so that the coding efficiency is reduced. On the other hand, when the M value is large, the inter-frame distance increases, so that the value of the motion vector tends to increase. However, especially in a stationary scene, the number of hierarchical layers in the time direction increases, so that the restrictions on the distribution of code amounts according to the layers (layers) are relaxed, so that the coding efficiency is improved. As an example, when the M value is changed from 8 to 4, the value of the motion vector is reduced to 1/2, and when the M value is changed from 4 to 8, the value of the motion vector is doubled.

  Note that Non-Patent Document 1 introduces the concept of SOP (Set of Pictures). The SOP is a unit that describes the coding order and reference relationship of each AU (Access Unit) when performing temporal layer coding. Temporal hierarchical coding is coding that allows a frame to be partially extracted from a video of a plurality of frames.

The SOP structure includes a structure of L = 0, a structure of L = 1, a structure of L = 2, and a structure of L = 3. As shown in FIG. 15, Lx (x = 0, 1, 2, 3) has the following structure.
Structure of L = 0: SOP structure composed of only pictures having a Temporal ID of 0 (that is, the number of pictures included in the SOP is one. It can be said that L indicating the maximum Temporal ID is 0). )
L = 1 structure: SOP structure composed of a picture with a Temporal ID of 0 and a picture with a 1 (that is, the number of pictures included in the SOP is two. L indicating the maximum Temporal ID is 1) It can also be said.)
L = 2 structure: SOP structure composed of a picture with a Temporal ID of 0, one picture, and two pictures (that is, the number of pictures included in the SOP is three. The maximum Temporal ID is It can be said that L shown is 2.)
L = 3 structure: SOP structure composed of a picture with a Temporal ID of 0, one picture, two pictures, and three pictures (that is, the number of pictures included in the SOP is four. It can be said that L indicating Temporal ID is 3.)

  In the description of the present specification, M = 1 corresponds to the SOP having the structure of L = 0, M = 2 corresponds to the SOP having the structure of L = 1 when N = 1 (see FIG. 15), and M = 3 corresponds to the SOP having the structure of L = 1 when N = 2 (see FIG. 15), M = 4 corresponds to the SOP of the structure of L = 2, and M = 8 corresponds to the SOP of the structure of L = 3. Corresponding to

  For a stationary scene (for example, a scene in which an object in the screen or the entire screen does not move quickly), as described above, the larger the reference picture interval (M value), the higher the coding efficiency. Therefore, in order to encode a high-definition video such as 8K at a low rate, it is preferable that the video encoding apparatus basically operates at M = 8.

  However, as described above, when the M value is increased, the value of the motion vector tends to increase. Therefore, especially in a scene in which an object on the screen or the entire screen moves quickly in the vertical direction, the image quality is reduced due to the motion vector restriction. Deteriorates. This is because an optimal motion vector cannot be selected at a slice boundary due to a motion vector restriction.

An object of the present invention is to provide a coding method for compressing a video screen after dividing the screen, and to suppress image quality degradation when using a coding method in which a motion vector is restricted near slice boundaries. And In addition, since it is necessary to consider switching between SDR and HDR in 4K and 8K as described above, an object of the present invention is to suppress the above-described image quality degradation in consideration of switching between SDR and HDR.

A video encoding method according to the present invention is a video encoding method for generating a bit stream using a plurality of SOP structures using information of a video signal regarding a dynamic range, and in a time direction, a video signal to be encoded. When switching from SDR to HDR, or when switching from HDR to SDR, the SOP structure of the first SOP after switching is Temporal to enable transmission of video signal information related to the dynamic range for switching the dynamic range. ID is set to SOP structure consisting of only pictures of 0, the information of the video signal relating to the dynamic range, when switching from SDR to HDR, or, when switching to the SDR from HDR, the transfer characteristics the in the bitstream It is characterized by setting.

Video encoding apparatus according to the present invention, in the time direction, when the video signal to be encoded switches from SDR to HDR, or when switching from HDR to SDR, video signal information about the dynamic range for switching the dynamic range In order to enable transmission, the coding structure control means for setting the SOP structure of the first SOP after the switching to an SOP structure composed of only pictures with a Temporal ID of 0 is provided. the information of the video signal relating to range, when switching from SDR to HDR, or, when switching to the SDR from HDR, and sets the transfer characteristics the in the bitstream.

A video encoding program according to the present invention uses a video signal information relating to a dynamic range, and in a time direction, a computer in a video encoding device that generates a bit stream using a plurality of SOP structures. When switching from SDR to HDR, or when switching from HDR to SDR, the SOP structure of the first SOP after switching is Temporal to enable transmission of video signal information related to the dynamic range for switching the dynamic range. ID to execute a process to set the SOP structure consisting of only pictures of 0, the information of the video signal relating to the dynamic range, when switching from SDR to HDR, or, when switching to the SDR from HDR, the bit stream It is characterized by having transfer characteristics set in

A video system according to the present invention includes the above-described video encoding device, an audio encoding unit that encodes an audio signal, and multiplexes and outputs a bit stream from the video encoding device and a bit stream from the audio encoding unit. And a multiplexing unit.
A video decoding device according to the present invention decodes a bit stream transmitted from the video encoding device.

  Advantageous Effects of Invention According to the present invention, it is possible to suppress deterioration of image quality while supporting switching between SDR and HDR.

It is a block diagram showing an example of composition of an embodiment of a video coding device. It is a block diagram showing an example of composition of an embodiment of a video decoding device. 5 is a flowchart illustrating an operation of the video encoding device according to the first embodiment. 6 is a flowchart illustrating an operation of the video encoding device according to the second embodiment. 13 is a flowchart illustrating an operation of the video encoding device according to the third embodiment. It is a block diagram showing an example of a picture system. It is a block diagram showing other examples of a video system. FIG. 2 is a block diagram illustrating a configuration example of an information processing system capable of realizing the functions of a video encoding device and a video decoding device. It is a block diagram which shows the principal part of a video encoding device. It is a block diagram which shows the principal part of a video decoding device. FIG. 4 is an explanatory diagram illustrating an example of screen division. FIG. 9 is an explanatory diagram for explaining motion vector restriction. FIG. 3 is an explanatory diagram showing an SOP structure. FIG. 4 is an explanatory diagram illustrating an example of a reference picture interval. FIG. 3 is an explanatory diagram showing an SOP structure.

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

  FIG. 1 is a block diagram illustrating a configuration example of an embodiment of a video encoding device. The video encoding device 100 illustrated in FIG. 1 includes an encoding unit 101, an analysis unit 111, a determination unit 112, and an M value determination unit 113. Although the video encoding device 100 performs the encoding process based on the HEVC standard, the video encoding device 100 may execute the encoding process based on another standard, for example, the H.264 / AVC standard. Hereinafter, a case where an 8K video is input will be described as an example.

  The encoding unit 101 includes a screen divider 102 for dividing an input image into a plurality of screens, a frequency transformer / quantizer 103, an inverse quantization / inverse frequency transformer 104, a buffer 105, a predictor 106, and an entropy encoder. 107.

  The screen divider 102 divides the screen of the input video into four screens (see FIG. 11). The frequency converter / quantizer 103 frequency-converts a prediction error image obtained by subtracting a prediction signal from an input video signal. The frequency converter / quantizer 103 further quantizes the frequency-converted prediction error image (frequency conversion coefficient). Hereinafter, the quantized frequency transform coefficient is referred to as a transform quantization value.

  The entropy encoder 107 entropy-encodes the prediction parameter and the transform quantization value, and outputs a bit stream. The prediction parameter is information related to CTU (Coding Tree Unit) and block prediction, such as a prediction mode (intra prediction, inter prediction), an intra prediction block size, an intra prediction direction, an inter prediction block size, and a motion vector.

  The predictor 106 generates a prediction signal for the input video signal. The prediction signal is generated based on intra prediction or inter-frame prediction.

  The inverse quantization / inverse frequency converter 104 inversely quantizes the transformed quantization value. Further, the inverse quantization / inverse frequency converter 104 performs inverse frequency conversion on the inversely quantized frequency conversion coefficient. The reconstructed prediction error image subjected to the inverse frequency conversion is supplied with a prediction signal and supplied to the buffer 105. The buffer 105 stores the reconstructed image.

  The analysis unit 111 analyzes the encoded statistical information. The determination unit 112 determines whether or not an optimum motion vector can be selected near a slice boundary by the above-described motion vector restriction based on the analysis result of the analysis unit 111. Note that the encoding statistical information is information on the encoding result of a past frame (for example, the frame immediately before the current encoding target frame), and a specific example of the encoding statistical information will be described later.

  Note that the vicinity of the slice boundary is an area where an optimal motion vector cannot be selected. However, when the following control is realized, for example, a range of ± 128 pixels or a range of ± 256 pixels from the slice boundary is used for convenience. May be set near the slice boundary. Further, when implementing the following control, the range of “near the slice boundary” may be changed as appropriate according to the state of the video (movement is large / small). For example, when the occurrence ratio of a motion vector having a large value is high, the range of “near a slice boundary” may be set wider.

  The M value determination unit 113 adaptively determines the M value based on the determination result of the determination unit 112. As described above, determining the M value is equivalent to determining the Lx (x = 0, 1, 2, 3) structure in the SOP structure. The coding statistical information will be described later.

  FIG. 2 is a block diagram illustrating a configuration example of an embodiment of a video decoding device. The video decoding device 200 illustrated in FIG. 2 includes an entropy decoder 202, an inverse quantization / inverse frequency converter 203, a predictor 204, and a buffer 205.

  The entropy decoder 202 entropy-decodes a video bitstream. The entropy decoder 202 supplies the transform quantization value subjected to the entropy decoding to the inverse quantization / inverse frequency converter 203.

  The inverse quantization / inverse frequency converter 203 inversely quantizes the transform quantization values of luminance and chrominance with a quantization step width to obtain a frequency transform coefficient. Further, the inverse quantization / inverse frequency converter 203 performs inverse frequency conversion on the inversely quantized frequency conversion coefficient.

  After the inverse frequency conversion, the predictor 204 generates a prediction signal using the image of the reconstructed picture stored in the buffer 205 (the prediction is also called motion compensation prediction or MC reference). The reconstructed prediction error image subjected to the inverse frequency transform by the inverse quantization / inverse frequency converter 203 is supplied with the prediction signal supplied from the predictor 204 and supplied to the buffer 205 as a reconstructed picture. Then, the reconstructed picture stored in the buffer 205 is output as a decoded video.

  Next, operations of the analysis unit 111, the determination unit 112, and the M-value determination unit 113 in the video encoding device 100 will be described.

Embodiment 1 FIG.
FIG. 3 is a flowchart showing the operation of the video encoding device 100 shown in FIG. 1 according to the first embodiment. In the first embodiment, it is assumed that an 8K video is divided into four (see FIG. 11), and there is a motion vector restriction near a slice boundary. Also, ± 128 is taken as an example of the motion vector limit. The fact that an 8K video is divided into four parts and that there are motion vector restrictions is the same in other embodiments. Note that the initial value of the M value is 8 (M = 8).

The analysis unit 111 analyzes a past encoding result (eg, the encoding result of the immediately preceding frame) stored in the buffer 105. Specifically, the analysis unit 111 calculates an average value or a median value of the motion vectors in blocks other than the slice boundary (hereinafter, the average value or the median value is referred to as _Mavg ) (step S101). In the first embodiment, the coding statistical information is a value of a motion vector, and the analysis result is an average value or a median value of the motion vectors.

The determination unit 112 determines how large the value of _Mavg is based on ± 128 as the motion vector limit (step S102).

Then, the M value determining unit 113 determines the M value based on the determination result of the magnitude of M _avg (step S103).

  The M value determination unit 113 determines the M value based on the determination result, for example, as follows.

(1) When M = 8:
| M _avg | ≦ 128 → Maintain M = 8 128 <| M _avg | ≦ 256 → M = 4 (1/2 of M = 8) determined 256 <| M _avg | ≦ 512 → M = 2 (M = 2 8 1/4) 512 <| M _avg | → M = 1 (M = （of 8)

(2) When M = 4:
| M _avg | ≦ 64 → M = 8 determined 64 <| M _avg | ≦ 128 → M = 4 maintained 128 <| M _avg | ≦ 256 → determined M = 2 256 <| M _avg | → M = 1 Decided on

When the M value is set to 8, even when the M value is any other value, the M value determination unit 113 sets the M value to 8 in the same manner as in the above cases (1) and (2). When it is estimated that the value of the motion vector near the slice boundary falls within ± 128, the M value is returned to 8. In other words, when it is estimated that the optimal motion vector can be selected near the slice boundary under the motion vector restriction, the M value determining unit 113 returns the M value to 8. In other cases, depending on the M _avg, the motion vector value in the vicinity of a slice boundary determining M value to fit within ± 128.

  Note that the above case classification (threshold setting) is merely an example, and the threshold may be changed or finer case classification may be performed.

  The control of the video encoding device according to the first embodiment is based on the following concept.

  When the video is a video of a scene in which the entire screen moves fast, the ratio of the number of motion vectors having a large value to all the generated motion vectors is high near the slice boundary and other than near the slice boundary. However, since there is a motion vector restriction, an optimal motion vector may not be selected near the slice boundary. Therefore, the determination unit 112 determines a code based on a motion vector as coding statistical information generated in an area other than the slice boundary (there is no regular motion vector, in other words, an optimal motion vector because there is no motion vector restriction). It is estimated whether or not the screen to be converted is a screen of a video of a fast-moving scene. If the determination unit 112 estimates that the image is a video of a fast-moving scene, the M value determination unit 113 changes the M value so that an optimal motion vector can be selected near the slice boundary.

  In the case of a video of a fast-moving scene, the optimal motion vector may not be selected near the slice boundary. This is equivalent to the assumption that an optimal motion vector has not been selected near the slice boundary.

  Further, as described above, the M value and the SOP structure are correlated. Therefore, determining the M value by the M value determining unit 113 is equivalent to determining the SOP structure (that is, the Lx (x = 0, 1, 2, 3) structure).

Embodiment 2. FIG.
FIG. 4 is a flowchart showing the operation of the video encoding device 100 shown in FIG. 1 according to the second embodiment.

The analysis unit 111 analyzes a past encoding result (eg, the encoding result of the immediately preceding frame) stored in the buffer 105. Specifically, the analysis unit 111, all blocks in the range other than the slice boundary (e.g., PU: Prediction Unit) with respect to, the intra prediction (intra-prediction) and calculating the ratio P ₁ of the block used is (step S201), for all the blocks in the vicinity of a slice boundary, and calculates the ratio _{P 2} of the blocks used are intra prediction (step S202). In the second embodiment, the coding statistical information is the prediction mode of the block near the slice boundary (specifically, the number of blocks for intra prediction), and the analysis result is the ratio P ₁ and the ratio P _{1 2} .

Determination unit 112 compares the ratio _{P 1} and the ratio _{P 2,} determines their degree of divergence. Specifically, as compared with the ratio P _1, it determines whether or not the ratio P ₂ is quite large. Determination unit 112, for example, determines whether the difference between the ratio _{P 2} and the ratio _{P 1} exceeds a predetermined value (step S203).

M value determining unit 113, when the difference between the ratio _{P 2} and the ratio _{P 1} exceeds a predetermined value, the smaller the M value (step S204). Note that a plurality of predetermined values are provided. For example, when the difference exceeds the first predetermined value, the M value is reduced by a plurality of steps, and the difference exceeds the second predetermined value (<the first predetermined value). At times, the M value may be reduced by one step.

Further, M value determining unit 113, the difference between the ratio _{P 2} and the ratio _{P 1} is the case is less than the predetermined value, maintaining or M value, or increases the M value (step S205). For example, the M value determining unit 113 increases the M value when the difference is equal to or less than a third predetermined value (<second predetermined value), and maintains the M value when the difference exceeds the third predetermined value. I do.

  The control of the video encoding device according to the second embodiment is based on the following concept.

  When coding each block in a screen, the coding unit 101 can use any of an intra-screen prediction and an inter-screen prediction (inter prediction) as a prediction mode. When the video is a video of a scene in which the entire screen moves fast, it is considered that the occurrence rate of the number of motion vectors having a large value when the inter-screen prediction is used is high even near the slice boundary (the motion vector restriction is limited). If not). Since there is a motion vector restriction, an optimal motion vector (large motion vector) cannot be generated near the slice boundary, and as a result, it is considered that intra prediction is often used near the slice boundary. . Since there is no motion vector restriction other than near the slice boundary, it is considered that intra prediction is rarely used as compared with the vicinity of the slice boundary.

Therefore, if the ratio P ₁ and the ratio P ₂ are greatly different, the signal of the video of fast moving scenes are estimated to be input to the encoding unit 101.

In the case of a video of a fast-moving scene, the optimal motion vector may not be selected near the slice boundary. below, it is equivalent to the ratio P ₁ and the ratio P ₂ are largely different.

  As a predetermined value for determining whether there is a large deviation, for example, empirically or experimentally, if such a value is used as a threshold, an optimal motion vector may not be selected near a slice boundary. A value that can be estimated to have a possibility is selected.

Embodiment 3 FIG.
FIG. 5 is a flowchart showing the operation of the video encoding device 100 shown in FIG. 1 according to the third embodiment.

The analysis unit 111 analyzes a past encoding result (eg, the encoding result of the immediately preceding frame) stored in the buffer 105. Specifically, the analysis unit 111, the previous frame (e.g., two frames before the current encoding target frame) is calculated generated code amount C ₁ in the block in the vicinity of a slice boundary (step S301). Further, the analysis unit 111 calculates a generated code amount _{C 2} in the block near the slice boundary of the previous frame (step S302). In the third embodiment, the coding statistics are generated code amount of a block near the slice boundary, the analysis result is the generation code amount C ₁ and the generated code amount C _2.

Determination unit 112 compares the generated code amount C ₁ and the generated code amount C _2, determines their degree of divergence. Specifically, as compared to the amount of generated codes C _1, determines whether or not considerably large amount of generated codes C _2. Determination unit 112, for example, determines whether the difference between the generated code amount _{C 2} and the generated code amount _{C 1} exceeds a predetermined amount (step S303).

M value determining unit 113, when the difference between the generated code amount C ₂ and the generated code amount C ₁ exceeds a predetermined amount, the smaller the M value (step S304). Note that a plurality of predetermined amounts are provided. For example, when the difference exceeds the first predetermined amount, the M value is reduced by a plurality of steps, and the difference exceeds the second predetermined amount (<the first predetermined amount). At times, the M value may be reduced by one step.

Further, M value determining unit 113, when the difference between the generated code amount C ₂ and the generated code amount C ₁ is equal to or less than the predetermined amount, maintaining or M value, or increases the M value (step S305 ). For example, the M value determining unit 113 increases the M value when the difference is equal to or less than a third predetermined amount (<second predetermined amount), and maintains the M value when the difference exceeds the third predetermined amount. I do.

  The control of the video encoding device according to the third embodiment is based on the following concept.

  As described above, when a video of a scene in which the entire screen moves fast, it is considered that the ratio of the number of motion vectors having a large value when the inter-screen prediction is used is high even near the slice boundary (motion vector restriction). If not). However, since there is a motion vector restriction, an optimal motion vector (large motion vector) cannot be generated near a slice boundary, and as a result, intra prediction is often used near a slice boundary. Conceivable. In general, the generated code amount is larger when intra-picture prediction is used than when inter-picture prediction is used.

Therefore, as compared with the amount of generated codes C _1, when the generated code amount C ₂ is quite large, the signal of the video of fast moving scenes are estimated to have changed the situation that is input to the encoding unit 101.

In the case of a video of a fast-moving scene, the optimal motion vector may not be selected near the slice boundary. in is equivalent to the generated code amount C ₂ increases greatly.

  As a predetermined amount for determining whether or not a large increase has occurred, for example, empirically or experimentally, if such an amount is used as a threshold, an optimal motion vector may not be selected near a slice boundary. Is selected.

  As described above, in each of the above embodiments, the M value is adaptively switched based on the past encoding result (encoding statistical information). Based on the coding statistical information, it is estimated whether or not an optimum motion vector (in other words, a motion vector that does not exceed the motion vector limit) can be selected near the slice boundary under the motion vector limit. If it is estimated that it cannot be selected, the M value is changed to a smaller value. If it is determined that the motion vector can be selected, the M value at that time is considered to be able to select the optimal motion vector near the slice boundary under the motion vector restriction, so the M value is maintained or is set to a larger value. Is changed to

  As a result, it is possible to avoid a state where an optimum motion vector cannot be selected in the vicinity of a slice boundary due to the motion vector restriction as much as possible, and it is possible to reduce the possibility that local image quality degradation occurs. That is, since the M value is adaptively switched in accordance with the speed of the movement, a suitable image quality can be obtained.

  In addition, since the M value can be switched based on the encoding result (for example, the encoding result of the immediately preceding frame), the pre-analysis (analysis processing executed as pre-processing when encoding the current frame) can be performed. This need not be performed, and the processing time for encoding is prevented from being extended as compared with the case of performing pre-analysis.

  Note that, in the video encoding device 100, the analysis unit 111, the determination unit 112, and the M-value determination unit 113 are configured to incorporate any two or all of the first to third embodiments. May be.

  Further, in the video encoding device 100, the M-value determining unit 113 determines the encoding structure using the switching information of SDR and HDR which is set from outside, and furthermore, the entropy encoder 107 determines the switching information of SDR and HDR. May be transmitted to the video decoding device side.

  More specifically, the M value determining unit 113 controls the M value so that the coding sequence (CVS) can be terminated at a switching position (time position) between SDR and HDR set from the outside.

  For simplicity of description, the number of frames from the frame at the current time position to the frame at the switching time position is fNumSwitch, and the temporarily determined M value is M.

  When fNumSwitch is 1 or more and M is larger than fNumSwitch, the M value determination unit 113 updates M to a value equal to or less than fNumSwitch.

  In other cases, when fNumSwitch is 0, the M value determination unit sets M to 1 so that CVS is terminated in a previously encoded frame. That is, the video encoding device compresses the current frame as an IDR picture. Furthermore, the entropy encoder 107 sets the switched SDR or HDR information in the transfer_characteristics syntax of the VPS of the SPS of the IDR picture in order to transmit the switching information between SDR and HDR to the video decoding device side. For example, when switching to HLG HDR, set transfer_characteristics syntax to 18; when switching to PQ HDR, set transfer_characteristics syntax to 16; and when switching to Rec.ITU-R BT.2020 SDR, set transfer_characteristics syntax to 14. Is set, and when switching to SDR of IEC 61966-2-4, set transfer_characteristics syntax to 11, and when switching to SDR of Rec. ITU-R BT.709, set 1 to transfer_characteristics syntax. At this time, the entropy encoder 107 may output the EOS bit stream before the IDR picture bit stream.

  In other cases, the M value determination unit 113 outputs M as it is.

  The relationship between the value of the transfer_characteristics syntax corresponding to the above-mentioned SDR and HDR and the characteristics is as shown in the following table.

  The video decoding device illustrated in FIG. 2 converts a bit stream encoded using an M value set within a range that satisfies a motion vector restriction as illustrated in the first to third embodiments. Decrypt.

  Further, the video decoding device shown in FIG. 2 can also receive the switching information between SDR and HDR transmitted from the video encoding device side by decoding the bit stream.

  Specifically, the entropy decoder 202 of the video decoding device can receive the switching information between SDR and HDR by decoding the value of the transfer_characteristics syntax of the VPS of the SPS. For example, if the transfer_characteristics syntax is 18, a switch to HLG HDR is received, if the transfer_characteristics syntax is 16, a switch to PDR HDR is received, and if the transfer_characteristics syntax is 14, Rec.ITU-R BT.2020 SDR. When the transfer_characteristics syntax is 11, a switch to IEC 61966-2-4 SDR is received, and when the transfer_characteristics syntax is 1, a switch to Rec. ITU-R BT.709 can be received. Here, it goes without saying that switching between SDR and HDR is received (detected) only by decoding the SPS of the IDR picture coded with M = 1. It goes without saying that the EOS bit stream may be received (detected) before the IDR bit stream.

  A receiving terminal using the above-described video decoding device can know switching information between SDR and HDR, and can adjust video display according to characteristics of a video signal. In other words, it is possible to display an image in which image quality deterioration is suppressed while supporting switching display between SDR and HDR.

  FIG. 6 is a block diagram illustrating an example of a video system. The video system shown in FIG. 6 is a system in which the video encoding device 100 of each of the above embodiments and the video decoding device 200 shown in FIG. 2 are connected by a wireless transmission line or a wired transmission line 300. The video encoding device 100 is the video encoding device 100 according to any one of the first to third embodiments. However, in the video encoding device 100, any one of the first to third embodiments is used. The analysis unit 111, the determination unit 112, and the M-value determination unit 113 may be configured to execute two or all processes.

  In the above example, the transmission means for transmitting the switching information between SDR and HDR to the video decoding side is realized by the entropy encoder 107. Decoding means for decoding the coded video and the switching information between SDR and HDR transmitted from the video coding side is realized by the entropy decoder 202. However, the entropy encoder that performs entropy encoding is configured separately from the multiplexer that multiplexes the data encoded by the entropy encoder and the switching information between SDR and HDR, and entropy decoding that performs entropy decoding The video system is composed of parts that do not include the multiplexer, if the demultiplexer is configured separately from the demultiplexer that separates SDR and HDR switching information and video from the multiplexed bit stream. The system may be configured by a video encoding device to be implemented and a video decoding device configured by a portion not including the demultiplexer.

  FIG. 7 is a block diagram showing another example of the video system. The video system shown in FIG. 7 includes an audio encoding unit 401, a video encoding unit 402, and a multiplexing unit 403.

  The audio encoding unit 401 converts an audio signal of data (content) including video and audio into, for example, the MPEG-4 AAC (Advanced Audio Coding) standard or the MPEG-4 ALS standard defined by the ARIB STD-B32 standard. (Audio Lossless Coding) to create and output an audio bit stream by encoding.

  The video encoding unit 402 is configured as shown in FIG. 1, for example, and creates and outputs a video bit stream.

  The multiplexing unit 403 creates and outputs an audio bit stream by multiplexing an audio bit stream, a video bit stream, and other information based on, for example, the ARIB STD-B32 standard.

  Further, each of the above embodiments can be configured by hardware, but can also be realized by a computer program.

  The information processing system shown in FIG. 8 includes a processor 1001, a program memory 1002, a storage medium 1003 for storing video data, and a storage medium 1004 for storing a bit stream. The storage medium 1003 and the storage medium 1004 may be separate storage media, or may be storage areas composed of the same storage medium. As the storage medium, a magnetic storage medium such as a hard disk can be used.

  In the information processing system shown in FIG. 8, a program (a video encoding program) for realizing the function of each block (excluding the buffer block) shown in each of FIGS. Or a video decoding program). Then, the processor 1001 performs the processing according to the program stored in the program memory 1002, thereby realizing the functions of the video encoding device or the video decoding device shown in each of FIGS.

  FIG. 9 is a block diagram illustrating a main part of the video encoding device. As illustrated in FIG. 9, the video encoding device 10 analyzes the encoding statistical information and analyzes the encoded statistical information (equivalent to the analyzing unit 111 in the embodiment). An estimating unit 12 for estimating whether or not an optimal motion vector can be selected (in the embodiment, realized by the determining unit 112), and a code based on the estimation result of the estimating unit 12 and the switching information between SDR and HDR An SOP structure composed of only pictures with a Temporal ID of 0, an SOP structure composed of a picture with a Temporal ID of 0 and a picture of 1, a picture with a Temporal ID of 0, a picture of 1 and a picture of 2 The coding structure determination unit 13 (actually determines an SOP structure composed of a picture having a Temporal ID of 0, an SOP structure composed of one picture, one picture, two pictures, and three pictures. In the embodiment, this is realized by the M value determination unit 113.) and the transmission unit 14 (in the embodiment, realized by the entropy encoder 107) for transmitting switching information between SDR and HDR to the video decoding side. Prepare.

  FIG. 10 is a block diagram showing a main part of the video decoding device. As illustrated in FIG. 10, the video decoding device 20 includes an SOP structure including only a picture with a Temporal ID of 0, an SOP structure including a picture with a Temporal ID of 0 and a picture with a 1 and a picture with a Temporal ID of 0. Video encoded with one of the following: an SOP structure consisting of one picture, one picture and two pictures, and an SOP structure consisting of a picture with a Temporal ID of 0, one picture, two pictures, and three pictures. And a decoding unit 21 (in the embodiment, realized by the entropy decoder 202) for decoding switching information between SDR and HDR transmitted from the video encoding side.

  Note that the decoding unit 21 has an SOP structure composed of only a picture with a Temporal ID of 0, an SOP structure composed of a picture with a Temporal ID of 0, and a picture with a Temporal ID of 0, and a Temporal ID of SOP structure consisting of 0 pictures, 1 picture, and 2 pictures, and SOP structure consisting of pictures with Temporal ID of 0, 1 picture, 2 pictures, and 3 pictures A bitstream encoded based on the structure can be decoded.

  Further, when the decoding unit 21 is divided into four slices as shown in FIG. 11 and the PU of one slice refers to another slice for motion compensation (MC) as shown in FIG. The MC reference of the same PU across the slice boundary is limited to refer to only pixels within 128 lines from the slice boundary, and the encoded bit stream can be decoded.

  In the embodiment, when handling a 120P moving image, the following SOP structure as shown in FIG. 13 can be used on the video encoding and decoding side.

Structure of L = 0: SOP structure composed of only pictures with Temporal ID of 0 (that is, the number of pictures included in the SOP is one. It can be said that L indicating the maximum Temporal ID is 0). )
L = 1 structure: SOP structure composed of a picture with a Temporal ID of 0 and a picture with a 1 (or M) (that is, the number of pictures included in the SOP is two. L indicating the maximum Temporal ID) Is 1 (or M).)
L = 2 structure: SOP structure composed of a picture with a Temporal ID of 0, 1 picture, and 2 (or M) pictures (that is, the number of pictures included in the SOP is three). It can be said that L indicating the maximum Temporal ID is 2 (or M).)
L = 3 structure: SOP structure composed of a picture with a Temporal ID of 0, 1 picture, 2 pictures, and 3 (or M) pictures (that is, the number of pictures included in the SOP is four) It can be said that L indicating the maximum Temporal ID is 3 (or M).)
L = 4 structure: SOP structure composed of a picture with a Temporal ID of 0, 1 picture, 2 pictures, 3 pictures, and 4 (or M) pictures (that is, pictures included in the SOP) Is 4. The L indicating the maximum Temporal ID can be said to be 4 (or M).)

REFERENCE SIGNS LIST 10 video encoding device 11 analyzing unit 12 estimating unit 13 encoding structure determining unit 14 transmission unit 20 video decoding device 21 decoding unit 100 video encoding device 101 encoding unit 102 screen divider 103 frequency transform / quantizer 104 inverse quantum Encoding / Inverse Frequency Transformer 105 Buffer 106 Predictor 107 Entropy Encoder 111 Analysis Unit 112 Judgment Unit 113 M-Value Determination Unit 200 Video Decoding Device 202 Entropy Decoder 203 Dequantization / Inverse Frequency Transformer 204 Predictor 205 Buffer 401 Audio encoding unit 402 Video encoding unit 403 Multiplexing unit 1001 Processor 1002 Program memory 1003, 10004 Storage medium

Claims (4)

A video encoding method for generating a bit stream using a plurality of SOP structures using information of a video signal regarding a dynamic range,
In the time direction, when the video signal to be encoded switches from SDR (Standard Dynamic Range) to HDR (High Dynamic Range), or switches from HDR to SDR, the video related to the dynamic range for switching the dynamic range In order to enable transmission of signal information, the SOP structure of the first SOP after switching is set to an SOP structure composed of only pictures with a Temporal ID of 0,
The information of the video signal relating to the dynamic range, when switching from the SDR to the HDR, or, when from the HDR switched to the SDR, video coding and setting the transfer characteristics The in said bit stream Method. A video encoding device that generates a bit stream using a plurality of SOP structures using information of a video signal regarding a dynamic range,
In the time direction, when the video signal to be encoded switches from SDR (Standard Dynamic Range) to HDR (High Dynamic Range), or switches from HDR to SDR, the video related to the dynamic range for switching the dynamic range In order to enable transmission of signal information, encoding structure control means for setting the SOP structure of the first SOP after switching to an SOP structure composed of only a picture with a Temporal ID of 0 is provided.
The coding structure control means, the information of the video signal relating to the dynamic range, when from the SDR switched to the HDR, or, when from the HDR switched to the SDR, sets the transfer characteristics The in said bit stream A video encoding device characterized by the above-mentioned. Using information of the video signal regarding the dynamic range, a computer in a video encoding device that generates a bit stream using a plurality of SOP structures,
In the time direction, when the video signal to be encoded switches from SDR (Standard Dynamic Range) to HDR (High Dynamic Range), or switches from HDR to SDR, the video related to the dynamic range for switching the dynamic range In order to enable transmission of signal information, a process is performed to set the SOP structure of the first SOP after switching to an SOP structure composed of only pictures with a Temporal ID of 0,
Wherein the information of the video signal relating to the dynamic range, when from the SDR switched to the HDR, or, when from the HDR switched to the SDR, video encoding program for setting the transfer characteristics The in the bit stream. A video encoding device according to claim 2,
An audio encoding unit that encodes an audio signal;
A video system, comprising: a multiplexing unit that multiplexes and outputs a bit stream from the video coding device and a bit stream from the audio coding unit.

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