JP2020096279A - Prediction image generation device, moving image decoding device, and moving image encoding device - Google Patents

Abstract

To provide a prediction image generation device, a moving image decoding device, and a moving image encoding device, in which encoding efficiency does not decrease in prediction to improve image quality using gradient images even if it is not a specific pixel bit length.SOLUTION: In the moving image decoding device, a BIO (Bi-directional optical flow) unit of an inter-prediction image generation unit has a prediction image generation unit for generating a prediction image from two interpolation images by using a bidirectional gradient change process according to a gradient change. The prediction image generation unit generates a prediction image by right-shifting values of an interpolation image and a gradient prediction image according to a pixel bit length to derive a modified value so that arithmetic accuracy of calculation of the correlation parameter for each processing unit is suppressed to less than a prescribed value.SELECTED DRAWING: Figure 12

Description

Embodiments of the present invention relate to a predictive image generation device, a moving image decoding device, and a moving image encoding device.

In order to efficiently transmit or record a moving image, a moving image encoding device that generates encoded data by encoding the moving image, and a moving image that generates a decoded image by decoding the encoded data An image decoding device is used.

Specific examples of the moving image coding method include H.264/AVC and HEVC (High-Efficiency Video Coding) method.

In such a moving image coding method, an image (picture) that constitutes a moving image is a slice obtained by dividing the image, and a coding tree unit (CTU: Coding Tree Unit) obtained by dividing the slice. ), a coding unit obtained by dividing the coding tree unit (sometimes called a coding unit (CU)), and a transform unit (TU: obtained by dividing the coding unit). CU is encoded/decoded for each CU.

In addition, in such a moving image coding method, a predicted image is usually generated based on a locally decoded image obtained by coding/decoding an input image, and the predicted image is generated from the input image (original image). The prediction error obtained by the subtraction (also referred to as “difference image” or “residual image”) is encoded. As a method of generating a predicted image, inter-screen prediction (inter prediction) and intra-screen prediction (intra prediction) can be mentioned.

Further, Non-Patent Document 1 can be cited as a technique of recent video encoding and decoding. Non-Patent Document 2 discloses a BIO technique that uses a gradient image to derive a high image quality when deriving a predicted image from motion compensation (interpolation image) of bi-prediction.

"Versatile Video Coding (Draft 3)", JVET-L1001, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11, 2018 "CE9-related: Complexity reduction and bit-width control for bi-directional optical flow (BIO)", JVET-L0256, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11, 2018

In the prediction (BIO prediction) using the BIO process for improving the image quality by using the gradient image when deriving the predicted image in Non-Patent Document 2, the coding efficiency decreases except for a specific pixel bit length. was there. Further, in the BIO process, since the units of the read blocks are duplicated, there is a problem that the padding process is required outside the coding unit.

The two interpolated images include a predictive image generation unit that uses a bidirectional gradient change process that generates a predicted image by a gradient change, and the bidirectional gradient change process uses two interpolated images to generate L0 for each coding unit. L0, L1 prediction generation unit that generates a prediction image and an L1 prediction image, a gradient image generation unit that generates four gradient images in the horizontal and vertical directions from the L0 prediction image and the L1 prediction image, and the L0 prediction From the sum of products of the image, the L1 predicted image, and the four gradient images, a correlation parameter calculation unit that calculates a correlation parameter for each processing unit, and motion compensation that derives a value that corrects the bidirectional predicted image from the correlation parameter A correction value derivation unit and a bidirectional prediction image generation unit that generates a prediction image from the motion compensation correction value are provided, and in the gradient image generation unit and the correlation parameter calculation unit, the calculation accuracy of the correlation parameter calculation is equal to or less than a certain value. In order to suppress, the values of the L0 prediction image, the L1 prediction image, and the gradient prediction image are right-shifted according to the pixel bit length.

In addition, a prediction image generation unit that uses bidirectional gradient change processing that generates a prediction image from two interpolated images by gradient change is provided, and the bidirectional gradient change processing is performed for each coding unit from the two interpolated images. L0 prediction image and L0 prediction generation unit for generating L1 prediction image, the L0 prediction image and the L1 prediction image, the horizontal direction, a gradient image generation unit for generating four vertical gradient images,
From the product sum operation of the L0 predicted image, the L1 predicted image, and the four gradient images, a correlation parameter calculation unit that calculates a correlation parameter for each processing unit, and from the correlation parameter, derive a value that modifies the bidirectional predicted image. A motion compensation correction value derivation unit and a bidirectional prediction image generation unit that generates a prediction image from the motion compensation correction value. In the correlation parameter calculation unit, the processing unit for calculating the correlation parameter is an encoding unit. It is characterized in that it is a block independently divided by.

According to the above configuration, it is possible to solve any of the above problems.

It is a schematic diagram showing the composition of the image transmission system concerning this embodiment. It is the figure which showed the structure of the transmission apparatus which mounts the moving image encoding apparatus which concerns on this embodiment, and the receiving apparatus which mounts the moving image decoding apparatus. (a) shows a transmitter equipped with a moving picture coding device, and (b) shows a receiver equipped with a moving picture decoding device. It is the figure which showed the structure of the recording device which mounts the moving image encoding apparatus which concerns on this embodiment, and the reproducing|regenerating apparatus which mounts a moving image decoding apparatus. (a) shows a recording device equipped with a moving image encoding device, and (b) shows a reproducing device equipped with a moving image decoding device. It is a figure which shows the hierarchical structure of the data of an encoding stream. It is a figure which shows the example of division of CTU. It is a conceptual diagram which shows an example of a reference picture and a reference picture list. It is a schematic diagram showing the composition of a moving picture decoding device. It is a schematic diagram showing the composition of the inter prediction parameter decoding part. It is a schematic diagram showing composition of a merge prediction parameter derivation part and an AMVP prediction parameter derivation part. It is a schematic diagram showing the composition of the inter prediction picture generation part. It is a figure showing an example of a flow chart explaining a flow of processing which a motion compensation part provided with a motion compensation function using BIO prediction concerning this embodiment derives a prediction picture. It is a schematic diagram showing the composition of the BIO section concerning this embodiment. It is a figure which shows an example of the area|region which a BIO part which concerns on this embodiment performs BIO padding. It is a figure showing an example of a unit of BIO processing of a BIO section and a reading field concerning this embodiment. It is a block diagram showing the composition of a moving picture coding device. It is a schematic diagram showing the composition of the inter prediction parameter coding part.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a configuration of an image transmission system 1 according to this embodiment.

The image transmission system 1 is a system that transmits an encoded stream obtained by encoding an image to be encoded, decodes the transmitted encoded stream, and displays an image. The image transmission system 1 is configured to include a moving image encoding device (image encoding device) 11, a network 21, a moving image decoding device (image decoding device) 31, and a moving image display device (image display device) 41. ..

The image T is input to the moving image encoding device 11.

The network 21 transmits the encoded stream Te generated by the moving image encoding device 11 to the moving image decoding device 31. The network 21 is the Internet, a wide area network (WAN: Wide Area Network), a small network (LAN: Local Area Network), or a combination thereof. The network 21 is not necessarily a bidirectional communication network, but may be a unidirectional communication network that transmits broadcast waves such as terrestrial digital broadcasting and satellite broadcasting. Further, the network 21 may be replaced with a storage medium such as a DVD (Digital Versatile Disc: registered trademark) or a BD (Blue-ray Disc: registered trademark) that records the encoded stream Te.

The moving image decoding device 31 decodes each of the encoded streams Te transmitted by the network 21 and generates one or a plurality of decoded images Td.

The moving image display device 41 displays all or part of one or a plurality of decoded images Td generated by the moving image decoding device 31. The moving image display device 41 includes a display device such as a liquid crystal display or an organic EL (Electro-luminescence) display. The form of the display includes stationary, mobile, HMD and the like. Further, when the video decoding device 31 has high processing capability, it displays an image with high image quality, and when it has only lower processing capability, it displays an image that does not require high processing capability or display capability. ..

<Operator>
The operators used in this specification are described below.

>> is right bit shift, << is left bit shift, & is bitwise AND, | is bitwise OR
, |= is an OR assignment operator, and || is a logical sum.

x?y:z is a ternary operator that takes y when x is true (other than 0) and z when x is false (0).

Clip3(a,b,c) is a function that clips c to a value greater than or equal to a and less than or equal to b. Returns a if c<a, returns b if c>b, and otherwise. Is a function that returns c (however, a<=b).

abs(a) is a function that returns the absolute value of a.

Int(a) is a function that returns the integer value of a.

floor(a) is a function that returns the largest integer less than or equal to a.

ceil(a) is a function that returns the smallest integer greater than or equal to a.

a/d represents division of a by d (rounding down after the decimal point).

a^b represents the b-th power of a.

sign(a) is a function that returns the sign of a. sign(a) = a>0? 1 :a==0? 0 :-1
log2(a) is a function that returns the logarithm with the base 2 of a.

Max(a, b) is a function that returns a when a>=b and b when a>b.

Min(a, b) is a function that returns a when a<=b and b when a>b.

Round(a) is a function that returns the rounded value of a. Round(a) = sign(a)*floor(abs(a)+0.5).

<Structure of encoded stream Te>
Prior to a detailed description of the moving image encoding device 11 and the moving image decoding device 31 according to the present embodiment, data of an encoded stream Te generated by the moving image encoding device 11 and decoded by the moving image decoding device 31. The structure will be described.

FIG. 4 is a diagram showing a hierarchical structure of data in the encoded stream Te. The coded stream Te illustratively includes a sequence and a plurality of pictures forming the sequence. 4A to 4F respectively show an encoded video sequence defining the sequence SEQ, an encoded picture defining the picture PICT, an encoding slice defining the slice S, and an encoding slice defining the slice data. It is a figure which shows the data, the coding tree unit contained in coding slice data, and the coding unit contained in a coding tree unit.

(Encoded video sequence)
In the encoded video sequence, a set of data referred to by the moving picture decoding apparatus 31 in order to decode the sequence SEQ to be processed is defined. As shown in FIG. 4(a), the sequence SEQ includes a video parameter set (Video Parameter Set), a sequence parameter set SPS (Sequence Parameter Set), a picture parameter set PPS (Picture Parameter Set), a picture PICT, and additional extension. Information SEI (Supplemental Enhancement Information) is included.

The video parameter set VPS is a set of coding parameters common to a plurality of moving pictures in a moving picture composed of a plurality of layers and a plurality of layers included in the moving picture and coding parameters related to individual layers. Sets are defined.

The sequence parameter set SPS defines a set of coding parameters that the moving image decoding apparatus 31 refers to in order to decode the target sequence. For example, the width and height of the picture are specified. There may be a plurality of SPSs. In that case, one of the plurality of SPSs is selected from the PPS.

The picture parameter set PPS defines a set of coding parameters that the moving picture decoding apparatus 31 refers to in order to decode each picture in the target sequence. For example, a quantization width reference value (pic_init_qp_minus26) used for decoding a picture and a flag (weighted_pred_flag) indicating application of weighted prediction are included. There may be a plurality of PPSs. In that case, one of the plurality of PPSs is selected from each picture in the target sequence.

(Encoded picture)
The coded picture defines a set of data that the moving picture decoding apparatus 31 refers to in order to decode the picture PICT to be processed. Picture PICT is sliced as shown in Fig. 4(b).
Includes 0 to slice NS-1 (NS is the total number of slices included in picture PICT).

In addition, hereinafter, when it is not necessary to distinguish each of the slice 0 to the slice NS-1, the suffix of the code may be omitted. The same applies to other data that is included in the coded stream Te described below and that has a subscript.

(Encoding slice)
In the encoded slice, a set of data referred to by the video decoding device 31 in order to decode the slice S to be processed is defined. The slice contains a slice header and slice data, as shown in FIG. 4(c).

The slice header includes a coding parameter group referred to by the video decoding device 31 in order to determine the decoding method of the target slice. The slice type designation information (slice_type) that designates the slice type is an example of an encoding parameter included in the slice header.

The slice types that can be designated by the slice type designation information include (1) an I slice that uses only intra prediction during encoding, (2) a unidirectional prediction that uses encoding during prediction, or a P slice that uses intra prediction. (3) B slices using unidirectional prediction, bidirectional prediction, or intra prediction at the time of encoding are included. Note that inter prediction is not limited to uni-prediction and bi-prediction, and a larger number of reference pictures may be used to generate a prediction image. Below, P
, B slice, it means a slice including a block for which inter prediction can be used.

The slice header may include a reference (pic_parameter_set_id) to the picture parameter set PPS.

(Encoded slice data)
The encoded slice data defines a set of data that the moving image decoding apparatus 31 refers to in order to decode the slice data to be processed. The slice data includes a CTU as shown in FIG. 4(d). The CTU is a fixed-size (eg, 64x64) block that constitutes a slice, and is sometimes referred to as the maximum coding unit (LCU).

(Encoding tree unit)
In FIG. 4(e), a set of data referred to by the video decoding device 31 in order to decode the CTU to be processed is defined. CTU is a basic coding process by recursive quadtree partitioning (QT (Quad Tree) partitioning), binary tree partitioning (BT (Binary Tree) partitioning) or ternary tree partitioning (TT (Ternary Tree) partitioning) It is divided into coding units CU, which are the basic units. The BT partition and the TT partition are collectively called a multi-tree partition (MT (Multi Tree) partition). A tree-structured node obtained by recursive quadtree partitioning is called a coding node. Intermediate nodes of the quadtree, the binary tree, and the ternary tree are coding nodes, and the CTU itself is also defined as the uppermost coding node.

CT, as CT information, a QT split flag (qt_split_cu_flag) indicating whether to perform QT split, an MT split flag (mtt_split_cu_flag) indicating the presence or absence of MT split, an MT split direction (mtt_split_cu_vertical_flag) indicating the split direction of MT split, The MT split type (mtt_split_cu_binary_flag) indicating the split type of MT split is included. qt_split_cu_flag, mtt_split_cu_vertical_flag and mtt_split_cu_binary_flag are transmitted for each coding node.

FIG. 5 is a diagram showing an example of CTU division. When qt_split_cu_flag is 1, the coding node is divided into four coding nodes (FIG. 5(b)).

When qt_split_cu_flag is 0 and mtt_split_cu_flag is 0, the coding node is not split and has one CU as a node (FIG. 5(a)). The CU is the end node of the coding node and is not further divided. The CU is a basic unit of encoding processing.

When mtt_split_cu_flag is 1, the coding node is MT-split as follows. If mtt_split_cu_vertical_flag is 0 and mtt_split_cu_binary_flag is 1, the coding node is 2.
The coding node is horizontally divided into two coding nodes (FIG. 5(d)), and when mtt_split_cu_vertical_flag is 1 and mtt_split_cu_binary_flag is 1, the coding node is vertically divided into two coding nodes (FIG. 5(c)). In addition, when mtt_split_cu_vertical_flag is 0 and mtt_split_cu_binary_flag is 0, the coding node is horizontally divided into three coding nodes (Fig. 5(f)), and when mtt_split_cu_vertical_flag is 1 and mtt_split_cu_binary_flag is 0, the coding node is 3. It is vertically divided into two coding nodes (Fig. 5(e)). These are shown in FIG. 5(g).

When the CTU size is 64x64 pixels, the CU size is 64x64 pixels, 64x32 pixels, 32x64 pixels, 32x32 pixels, 64x16 pixels, 16x64 pixels, 32x16 pixels, 16x32 pixels, 16x16 pixels, 64x8.
Pixel, 8x64 pixel, 32x8 pixel, 8x32 pixel, 16x8 pixel, 8x16 pixel, 8x8 pixel, 64x4 pixel, 4x64
It can be any of pixels, 32x4 pixels, 4x32 pixels, 16x4 pixels, 4x16 pixels, 8x4 pixels, 4x8 pixels, and 4x4 pixels.

(Encoding unit)
As shown in FIG. 4(f), a set of data referred to by the video decoding device 31 for decoding the encoding unit to be processed is defined. Specifically, the CU includes a CU header CUH, a prediction parameter, a conversion parameter, a quantized conversion coefficient, and the like. The prediction mode etc. are specified in the CU header.

The prediction process may be performed in CU units or may be performed in sub CU units obtained by further dividing the CU. When the CU and the sub CU have the same size, there is one sub CU in the CU. If the CU is larger than the size of the sub CU, the CU is divided into sub CUs. For example, if the CU is 8x8 and the sub-CU is 4x4, the CU is divided into four sub-CUs, which are divided into two horizontally and vertically.

There are two types of prediction (prediction mode): intra prediction and inter prediction. Intra prediction refers to prediction within the same picture, and inter prediction refers to prediction processing performed between different pictures (for example, between display times).

The transform/quantization process is performed in CU units, but the quantized transform coefficients may be entropy coded in subblock units such as 4x4.

(Prediction parameter)
The predicted image is derived from the prediction parameters associated with the block. The prediction parameters include intra prediction and inter prediction parameters.

The prediction parameters of inter prediction will be described below. The inter prediction parameter is composed of prediction list use flags predFlagL0 and predFlagL1, reference picture indexes refIdxL0 and refIdxL1, and motion vectors mvL0 and mvL1. The prediction list use flags predFlagL0 and predFlagL1 are flags indicating whether or not reference picture lists called L0 list and L1 list are used, and the reference picture list corresponding to a value of 1 is used. In addition, in the present specification, when it is referred to as “a flag indicating whether it is XX”, a flag other than 0 (for example, 1) is XX, 0 is not XX, and logical negation, logical product, etc. Treat 1 as true and 0 as false (same below). However, in an actual device or method, other values can be used as the true value and the false value.

Syntax elements for deriving inter prediction parameters include, for example, affine flag affine_flag, merge flag merge_flag, merge index merge_idx, inter prediction identifier inter_pred_idc, reference picture index refIdxLX, prediction vector index mvp_LX_idx, difference vector mvdLX, motion vector accuracy. There is a mode amvr_mode.

(Reference picture list)
The reference picture list is a list of reference pictures stored in the reference picture memory 306. FIG. 6 is a conceptual diagram showing an example of a reference picture and a reference picture list. In FIG. 6(a), a rectangle is a picture, an arrow is a picture reference relationship, a horizontal axis is time, I, P, and B in the rectangle are intra pictures, uni-predictive pictures, bi-predictive pictures, and numbers in the rectangle are decoded. Show the order. As shown in the figure, the decoding order of pictures is I0, P1, B2, B3, B4, and the display order is I0, B3, B2, B4, P1. FIG. 6B shows an example of the reference picture list of the picture B3 (target picture). The reference picture list is a list showing candidates for reference pictures, and one picture (slice) may have one or more reference picture lists. In the illustrated example, the target picture B3 has two reference picture lists, an L0 list RefPicList0 and an L1 list RefPicList1. In each CU, the reference picture index refIdxLX specifies which picture in the reference picture list RefPicListX (X=0 or 1) is actually referred to. The figure shows an example of refIdxL0=2 and refIdxL1=0. It should be noted that LX is a description method used when the L0 prediction and the L1 prediction are not distinguished, and hereinafter, the parameters for the L0 list and the parameters for the L1 list are distinguished by replacing LX with L0 and L1.

(Merge prediction and AMVP prediction)
The prediction parameter decoding (encoding) methods include a merge prediction (merge) mode and an AMVP (Advanced Motion Vector Prediction) mode, and the merge flag merge_flag is a flag for identifying these. The merge prediction mode is a mode in which the prediction list use flag predFlagLX (or inter prediction identifier inter_pred_idc), the reference picture index refIdxLX, and the motion vector mvLX are not included in the encoded data but are derived from the prediction parameters of the already processed neighboring blocks. .. The AMVP mode is a mode in which the inter prediction identifier inter_pred_idc, the reference picture index refIdxLX, and the motion vector mvLX are included in the encoded data. The motion vector mvLX is encoded as a prediction vector index mvp_LX_idx for identifying the prediction vector mvpLX, a difference vector mvdLX, and a motion vector precision mode amvr_mode. In addition to the merge prediction mode, affine flag affine_flag
There may be an affine prediction mode identified by As one form of the merge prediction mode, there may be a skip mode identified by a skip flag skip_flag. The skip mode is a mode in which a prediction parameter is derived and used by the same method as the merge mode, and a prediction error (residual image) is not included in encoded data. In other words, when the skip flag skip_flag is 1, only the skip flag skip_flag and the syntax related to the merge mode such as the merge index merge_idx are included in the target CU, and the motion vector and the like are not included in the encoded data. Therefore, when the skip flag skip_flag indicates that the skip mode is applied to the target CU, decoding of prediction parameters other than the skip flag skip_flag is omitted.

(Motion vector)
The motion vector mvLX indicates the shift amount between blocks on two different pictures. The prediction vector and the difference vector regarding the motion vector mvLX are called the prediction vector mvpLX and the difference vector mvdLX, respectively.

(Inter prediction identifier inter_pred_idc and prediction list usage flag predFlagLX)
The inter-prediction identifier inter_pred_idc is a value indicating the type and number of reference pictures, and takes any value of PRED_L0, PRED_L1, and PRED_BI. PRED_L0 and PRED_L1 indicate uni-prediction using one reference picture managed in the L0 list and the L1 list, respectively. PRED_BI indicates bi-prediction BiPred using two reference pictures managed by the L0 list and the L1 list.

The merge index merge_idx is an index indicating which prediction parameter is used as the prediction parameter of the target block among the prediction parameter candidates (merge candidates) derived from the processed block.

The relationship between the inter prediction identifier inter_pred_idc and the prediction list use flags predFlagL0 and predFlagL1 is as follows, and they can be converted mutually.

inter_pred_idc = (predFlagL1<<1)+predFlagL0
predFlagL0 = inter_pred_idc & 1
predFlagL1 = inter_pred_idc >> 1
(Judgment of bi-predictive biPred)
The flag biPred indicating whether it is bi-prediction BiPred can be derived depending on whether the two prediction list use flags are both 1. For example, it can be derived by the following formula.

biPred = (predFlagL0==1 && predFlagL1==1)
Alternatively, the flag biPred can be derived depending on whether the inter prediction identifier is a value indicating that two prediction lists (reference pictures) are used. For example, it can be derived by the following formula.

biPred = (inter_pred_idc==PRED_BI) ?1: 0
(Structure of video decoding device)
The configuration of the moving picture decoding device 31 (FIG. 7) according to the present embodiment will be described.

The moving image decoding device 31 includes an entropy decoding unit 301, a parameter decoding unit (prediction image decoding device) 302, a loop filter 305, a reference picture memory 306, a prediction parameter memory 307, a prediction image generation unit (prediction image generation device) 308, and an inverse. The quantization/inverse conversion unit 311 and the addition unit 312 are included. It should be noted that there is a configuration in which the moving image decoding device 31 does not include the loop filter 305 in accordance with the moving image encoding device 11 described later.

The parameter decoding unit 302 further includes a header decoding unit 3020 and a CT information decoding unit 3021 (not shown).
, And a CU decoding unit 3022 (prediction mode decoding unit), and the CU decoding unit 3022 further includes a TU decoding unit 3024. These may be collectively referred to as a decoding module. The header decoding unit 3020 decodes the parameter set information such as VPS, SPS, PPS and the slice header (slice information) from the encoded data. The CT information decoding unit 3021 decodes the CT from the encoded data. The CU decoding unit 3022 decodes the CU from the encoded data. The TU decoding unit 3024 decodes the QP update information (quantization correction value) and the quantized prediction error (residual_coding) from the encoded data when the TU includes a prediction error.

Further, the parameter decoding unit 302 is configured to include an inter prediction parameter decoding unit (prediction image generation device) 303 and an intra prediction parameter decoding unit 304 (not shown). The predicted image generation unit 308 includes an inter predicted image generation unit (predicted image generation device) 309 and an intra predicted image generation unit 310.

Further, although an example in which CTU and CU are used as a processing unit is described below, the processing is not limited to this example, and processing may be performed in sub CU units. Alternatively, the CTU and CU may be read as a block and the sub CU may be read as a sub block, and processing may be performed in block or sub block units.

The entropy decoding unit 301 performs entropy decoding on the coded stream Te input from the outside to decode individual codes (syntax elements).

The entropy decoding unit 301 outputs the decoded code to the parameter decoding unit 302. With the decoded code, for example, prediction mode predMode, merge flag merge_flag, merge index merge_idx, inter prediction identifier inter_pred_idc, reference picture index refIdxLX,
The prediction vector index mvp_LX_idx, the difference vector mvdLX, the motion vector accuracy mode amvr_mode, and the like. Control of which code is decoded is performed based on an instruction from the parameter decoding unit 302.

(Configuration of inter prediction parameter decoding unit)
The inter prediction parameter decoding unit 303 decodes the inter prediction parameter based on the code input from the entropy decoding unit 301 with reference to the prediction parameter stored in the prediction parameter memory 307. Further, the inter prediction parameter decoding unit 303 outputs the decoded inter prediction parameter to the prediction image generation unit 308 and stores it in the prediction parameter memory 307.

FIG. 8 is a schematic diagram showing the configuration of the inter prediction parameter decoding unit 303 according to the present embodiment. The inter prediction parameter decoding unit 303 includes a merge prediction unit 30374, a DMVR unit 30375, a sub-block prediction unit (affine prediction unit) 30372, an MMVD prediction unit (motion vector derivation unit) 30376, a Triangle prediction unit 30377, and an AMVP prediction parameter derivation unit 3032. , And an adding unit 3038. The merge prediction unit 30374 includes a merge prediction parameter derivation unit 3036. Since the AMVP prediction parameter derivation unit 3032, the merge prediction parameter derivation unit 3036, and the affine prediction unit 30372 are means common to the moving image coding device and the moving image decoding device, they are collectively referred to as the motion vector derivation unit (motion vector May be referred to as a derivation device).

The inter prediction parameter decoding unit 303 instructs the entropy decoding unit 301 to decode syntax elements related to inter prediction, and syntax elements included in the encoded data, for example, affine flag affine_flag, merge flag merge_flag, merge index merge_idx. , Inter prediction identifier inter_pred_idc, reference picture index refIdxLX, prediction vector index mvp_LX_idx, difference vector mvdLX, motion vector precision mode amvr_mode.

When the affine flag affine_flag is 1, that is, the affine prediction mode is indicated, the affine prediction unit 30372 derives the inter prediction parameter of the sub block.

When the merge flag merge_flag is 1, that is, indicates the merge prediction mode, the merge index merge_idx is decoded and output to the merge prediction parameter derivation unit 3036.

When the merge flag merge_flag is 0, that is, when it indicates the AMVP prediction mode, for example, the inter prediction identifier inter_pred_idc, the reference picture index refIdxLX, the prediction vector index mvp_LX_idx, and the difference vector mvdLX are decoded as AMVP prediction parameters. The AMVP prediction parameter derivation unit 3032 calculates the prediction vector mvpLX from the prediction vector index mvp_LX_idx.
Derive. The addition unit 3038 adds the derived prediction vector mvpLX and the difference vector mvdLX to derive a motion vector mvLX.

(Affine prediction unit)
The affine prediction unit 30372 derives the affine prediction parameter of the target block. In this embodiment, the motion vectors (mv0_x, mv0_y) (mv1_x, mv1_y) of the two control points (V0, V1) of the target block are derived as affine prediction parameters. Specifically, the motion vector of each control point may be derived by predicting from the motion vector of the block adjacent to the target block, or derived from the prediction vector derived as the motion vector of the control point and the encoded data. The motion vector of each control point may be derived from the sum of the difference vectors.

Note that the affine prediction unit 30372 may appropriately derive a parameter used for 4-parameter MVD affine prediction or a parameter used for 6-parameter MVD affine prediction.

(Merge prediction)
FIG. 9A is a schematic diagram showing the configuration of the merge prediction parameter derivation unit 3036 included in the merge prediction unit 30374. The merge prediction parameter derivation unit 3036 includes a merge candidate derivation unit 30361 and a merge candidate selection unit 30362. The merge candidate is the prediction list use flag predFlagLX,
The motion vector mvLX and the reference picture index refIdxLX are included and stored in the merge candidate list. An index is assigned to the merge candidates stored in the merge candidate list according to a predetermined rule.

The merge candidate derivation unit 30361 derives the merge candidate by using the motion vector of the decoded adjacent block and the reference picture index refIdxLX as they are. Other than that, the merge candidate derivation unit 30361 may apply a spatial merge candidate derivation process, a temporal merge candidate derivation process, a pairwise merge candidate derivation process, and a zero merge candidate derivation process described later.

As the spatial merge candidate derivation process, the merge candidate derivation unit 30361 reads the prediction parameter stored in the prediction parameter memory 307 according to a predetermined rule and sets it as a merge candidate. The reference picture can be specified by, for example, adjacent blocks within a predetermined range from the target block (for example, all or some of the blocks that respectively contact the target block left A1, right B1, upper right B0, lower left A0, and upper left B2). ) Is a prediction parameter related to each. Each merge candidate is called A1, B1, B0, A0, B2.

Here, A1, B1, B0, A0 and B2 are motion information derived from blocks including the following coordinates.

A1: (xCb-1, yCb + cbHeight-1)
B1: (xCb + cbWidth-1, yCb-1)
B0: (xCb + cbWidth, yCb-1)
A0: (xCb-1, yCb + cbHeight)
B2: (xCb-1, yCb-1)
As a temporal merge derivation process, the merge candidate derivation unit 30361, the lower right CBR of the target block, or, the prediction parameter of the block C in the reference image including the center coordinates, read from the prediction parameter memory 307 as a merge candidate Col, Store in merge candidate list mergeCandList[].

The pairwise deriving unit derives the pairwise candidate avgK and stores it in the merge candidate list mergeCandList[].

The merge candidate derivation unit 30361 derives zero merge candidates Z0,..., ZM in which the reference picture index refIdxLX is 0... M, and the X component and Y component of the motion vector mvLX are both 0, and stores them in the merge candidate list.

The order in which the merge candidate derivation unit 30361 or the pairwise derivation unit stores each merge candidate in the merge candidate list mergeCandList[] is, for example, spatial merge candidate (A1,B1,B0,A0,B2), temporal merge candidate Col, pairwise candidate. AvgK and ZeroCandK candidate ZeroCandK. Reference blocks that are not available (blocks are intra-predicted, etc.) are not stored in the merge candidate list.
i = 0
if( availableFlagA1)
mergeCandList[ i++ ]= A1
if( availableFlagB1)
mergeCandList[ i++ ]= B1
if( availableFlagB0)
mergeCandList[ i++ ]= B0
if( availableFlagA0)
mergeCandList[ i++ ]= A0
if( availableFlagB2)
mergeCandList[ i++ ]= B2
if( availableFlagCol)
mergeCandList[ i++ ]= Col
if( availableFlagAvgK ).
mergeCandList[ i++ ]= avgK
if( i <MaxNumMergeCand)
mergeCandList[ i++ ]= ZK
The upper left coordinates of the target block is (xCb, yCb), the width of the target block is cbWidth,
Let cbHeight be the height of the target block.

The merge candidate selecting unit 30362 selects the merge candidate N indicated by the merge index merge_idx from the merge candidates included in the merge candidate list by the following formula.

N = mergeCandList[merge_idx]
Here, N is a label indicating a merge candidate, and takes A1, B1, B0, A0, B2, Col, AvgK, ZeroCandK and the like. The motion information of the merge candidate indicated by the label N (mvLXN[0], mvLXN[1]) is indicated by predFlagLXN, refIdxLXN.

The merge candidate selection unit 30362 detects motion information of the selected merge candidate (mvLXN[0], mvLXN[1]).
, PredFlagLXN, refIdxLXN are selected as inter prediction parameters of the target block. The merge candidate selection unit 30362 stores the selected inter prediction parameter in the prediction parameter memory 307 and outputs it to the predicted image generation unit 308.

(MMVD prediction unit 30373)
The MMVD prediction unit 30373 adds the difference vector mvdLX to the center vector mvdLX (merge candidate motion vector) derived by the merge candidate derivation unit 30361 to derive a motion vector.

The MMVD prediction unit 30376 uses the merge candidate mergeCandList[] and the syntax base_candidate_idx, direction_idx, distance_idx that decodes or encodes encoded data into encoded data.
The motion vector mvLX[] is derived using. Furthermore, the syntax distance_list_idx for selecting the distance table may be encoded or decoded.

The MMVD prediction unit 30376 selects the center vector mvLN[] with base_candidate_idx.

N = mergeCandList[base_candidate_idx]
The MMVD prediction unit 30376 derives the base distance (mvdUnit[0], mvdUnit[1]) and the distance DistFromBaseMV.

dir_table_x[] = {8, -8, 0, 0, 6, -6, -6, 6}
dir_table_y[] = {0, 0, 8, -8, 6, -6, 6, -6}
mvdUnit[0] = dir_table_x[direction_idx]
mvdUnit[1] = dir_table_y[direction_idx]
DistFromBaseMV = DistanceTable[distance_idx]
The MMVD prediction unit 30376 derives the difference vector refineMv[].

firstMv[0] = (DistFromBaseMV<<shiftMMVD) * mvdUnit[0]
firstMv[1] = (DistFromBaseMV<<shiftMMVD) * mvdUnit[1]
Here, shiftMMVD is a value for adjusting the size of the difference vector so as to match the motion vector accuracy MVPREC in the motion compensation unit 3091 (interpolation unit).

refineMvL0[0] = firstMv[0]
refineMvL0[1] = firstMv[1]
refineMvL1[0] = -firstMv[0]
refineMvL1[1] = -firstMv[1]
Finally, the MMVD prediction unit 30376 derives the motion vector of the MMVD merge candidate from the difference vector refineMvLX and the center vector mvLXN as follows.
mvL0[ 0 ]= mvL0N[ 0 ]+ refineMvL0[0]
mvL0[ 1 ]= mvL0N[ 1 ]+ refineMvL0[1]
mvL1[ 0 ]= mvL1N[ 0 ]+ refineMvL1[0]
mvL1[ 1 ]= mvL1N[ 1 ]+ refineMvL1[1]
(AMVP prediction)
FIG. 9(b) is a schematic diagram showing the configuration of the AMVP prediction parameter derivation unit 3032 according to this embodiment. The AMVP prediction parameter derivation unit 3032 includes a vector candidate derivation unit 3033 and a vector candidate selection unit 3034. The vector candidate derivation unit 3033 derives a prediction vector candidate from the motion vector mvLX of the decoded adjacent block stored in the prediction parameter memory 307 based on the reference picture index refIdxLX, and stores it in the prediction vector candidate list mvpListLX[].

The vector candidate selecting unit 3034 selects the motion vector mvpListLX[mvp_LX_idx] indicated by the prediction vector index mvp_LX_idx from the prediction vector candidates in the prediction vector candidate list mvpListLX[] as the prediction vector mvpLX. The vector candidate selection unit 3034 outputs the selected prediction vector mvpLX to the addition unit 3038.

The addition unit 3038 adds the prediction vector mvpLX input from the AMVP prediction parameter derivation unit 3032 and the decoded difference vector mvdLX to calculate the motion vector mvLX. The addition unit 3038 outputs the calculated motion vector mvLX to the prediction image generation unit 308 and the prediction parameter memory 307.

mvLX[0] = mvpLX[0]+mvdLX[0]
mvLX[1] = mvpLX[1]+mvdLX[1]
The motion vector accuracy mode amvr_mode is a syntax for switching the accuracy of the motion vector derived in the AMVP mode. For example, in amvr_mode=0, 1, 2, 1/4 pixel, 1 pixel, or 4 pixel accuracy is switched.

When the motion vector precision is 1/16 precision, it is derived from amvr_mode as follows to change the motion vector difference of 1/4, 1, 4 pixel precision to the motion vector difference of 1/16 pixel precision. Dequantization may be performed using MvShift (=1<<amvr_mode).

mvdLX[0] = mvdLX[0] << (MvShift + 2)
mvdLX[1] = mvdLX[1] << (MvShift + 2)
The parameter decoding unit 302 may further derive mvdLX[] by decoding the following syntax.
・Abs_mvd_greater0_flag
・Abs_mvd_minus2
・Mvd_sign_flag
Decrypt. Then, the parameter decoding unit 302 decodes the difference vector 1Mvd[] from the syntax by using the following formula.

lMvd[ compIdx ]= abs_mvd_greater0_flag[ compIdx ]* (abs_mvd_minus2[ compIdx
] + 2) * (1 ?2 * mvd_sign_flag[ compIdx ])
Further, the decoded difference vector lMvd[] is the case of translation MVD (MotionModelIdc[ x ][ y ]==
0) is set to mvdLX, and in the case of control point MVD (MotionModelIdc[ x ][ y ]!=0), it is set to mvdCpLX.

if (MotionModelIdc[ x ][ y ]== 0)
mvdLX[ x0 ][ y0 ][ compIdx ]= lMvd[ compIdx]
else
mvdCpLX[ x0 ][ y0 ][ compIdx ]= lMvd[ compIdx ]<<2
(DMVR)
Next, the DMVR (Decoder side Motion Vector Refinement) processing performed by the DMVR unit 30375 will be described. The DMVR unit 30375, for the target CU, if the merge flag merge_flag indicates that the merge prediction mode is applied, or if the skip flag skip_flag indicates that the skip mode is applied, the merge prediction unit 30374. The motion vector mvLX of the target CU derived by is corrected using the reference image.

Specifically, when the prediction parameter derived by the merge prediction unit 30374 is bi-prediction, the motion vector is corrected using the prediction image derived from the motion vector corresponding to the two reference pictures. The corrected motion vector mvLX is supplied to the inter prediction image generation unit 309.

(Triangle prediction)
Next, the Triangle prediction will be described. In Triangle prediction, the target CU is divided into two triangular prediction units with a diagonal line or an opposite diagonal line as a boundary. The prediction image in each triangle prediction unit is derived by performing weighting mask processing on each pixel of the prediction image of the target CU (rectangular block including the triangle prediction unit) according to the pixel position. For example, a triangular image can be derived from a rectangular image by multiplying by a mask in which the pixels in the triangular area in the rectangular area are 1 and the areas other than the triangle are 0. In addition, after the inter prediction image is generated, the adaptive weighting process is applied to both regions sandwiching the diagonal line, and the adaptive weighting process using the two prediction images is performed to set 1 of the target CU (rectangular block). One predicted image is derived. This processing is called Triangle composition processing. Then, the transformation (inverse transformation) and the quantization (inverse quantization) processing are applied to the entire target CU. The Triangle prediction is applied only in the merge prediction mode or the skip mode.

The Triangle prediction unit 30377 derives prediction parameters corresponding to the two triangular regions used for Triangle prediction, and supplies the prediction parameters to the inter prediction image generation unit 309. The Triangle prediction may be configured without bi-prediction for simplification of processing. In this case, inter prediction parameters for unidirectional prediction are derived in one triangular area. Note that the derivation of the two predicted images and the synthesis using the predicted images are performed by the motion compensation unit 3091 and the Triangle synthesis unit 30952.

The loop filter 305 is a filter provided in the coding loop and removes block distortion and ringing distortion and improves image quality. The loop filter 305 applies filters such as a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the CU decoded image generated by the addition unit 312.

The reference picture memory 306 stores the decoded image of the CU generated by the addition unit 312 at a predetermined position for each target picture and target CU.

The prediction parameter memory 307 stores the prediction parameter in a predetermined position for each CTU or CU to be decoded. Specifically, the prediction parameter memory 307 stores the parameters decoded by the parameter decoding unit 302, the prediction mode predMode decoded by the entropy decoding unit 301, and the like.

A prediction mode predMode, a prediction parameter, and the like are input to the prediction image generation unit 308. Further, the predicted image generation unit 308 reads the reference picture from the reference picture memory 306. The predicted image generation unit 308 generates a predicted image of a block or sub-block using the prediction parameter and the read reference picture (reference picture block) in the prediction mode indicated by the prediction mode predMode. Here, the reference picture block is a set of pixels on the reference picture (usually called a block because it is a rectangle), and is an area referred to for generating a predicted image.

(Inter prediction image generation unit 309)
When the prediction mode predMode indicates the inter prediction mode, the inter prediction image generation unit 309 uses the inter prediction parameter input from the inter prediction parameter decoding unit 303 and the read reference picture to perform a prediction image of a block or sub-block by inter prediction. To generate.

FIG. 10 is a schematic diagram showing the configuration of the inter-prediction image generation unit 309 included in the prediction image generation unit 308 according to this embodiment. The inter prediction image generation unit 309 includes a motion compensation unit (prediction image generation device) 3091 and a synthesis unit 3095.

(Motion compensation)
The motion compensation unit 3091 (interpolation image generation unit 3091) uses the reference picture memory based on the inter prediction parameters (prediction list use flag predFlagLX, reference picture index refIdxLX, motion vector mvLX) input from the inter prediction parameter decoding unit 303. From 306, an interpolation image (motion compensation image) is generated by reading a block at a position shifted by the motion vector mvLX from the position of the target block in the reference picture RefPicLX specified by the reference picture index refIdxLX. Here, when the precision of the motion vector mvLX is not an integer precision, a filter called a motion compensation filter for generating pixels at decimal positions is applied to generate a motion compensated image.

The motion compensation unit 3091 first derives the integer position (xInt, yInt) and the phase (xFrac, yFrac) corresponding to the coordinate (x, y) in the prediction block by the following formula.

xInt = xPb+(mvLX[0]>>(log2(MVPREC)))+x
xFrac = mvLX[0]&(MVPREC -1)
yInt = yPb+(mvLX[1]>>(log2(MVPREC)))+y
yFrac = mvLX[1]&(MVPREC -1)
Here, (xPb,yPb) is the upper left coordinates of the block of bW*bH size, x=0...bW-1, y=0...bH-1, and MVPREC is the accuracy of motion vector mvLX (1/MVPREC Pixel accuracy). For example MVPREC=16.

The motion compensation unit 3091 derives a temporary image temp[][] by performing horizontal interpolation processing on the reference picture refImg using an interpolation filter. Σ below is the sum of k=0..N for k in NTAP-1, shift1 is a normalization parameter for adjusting the range of values, offset1=1<<(shift1-1).

temp[x][y] = (ΣmcFilter[xFrac][k]*refImg[xInt+k-NTAP/2+1][yInt]+offset1)>>shift1
Subsequently, the motion compensation unit 3091 derives an interpolated image Pred[][] by performing vertical interpolation processing on the temporary image temp[][]. Σ below is the sum of k=0..N for k in NTAP-1, shift2 is a normalization parameter for adjusting the range of values, and offset2=1<<(shift2-1).

Pred[x][y] = (ΣmcFilter[yFrac][k]*temp[x][y+k-NTAP/2+1]+offset2)>>shift2
The above interpolation image generation processing may be represented by Interpolation (refImg, xPb, yPb, bW, bH, mvLX).

(Synthesis section)
The combining unit 3095 refers to the interpolated image supplied from the motion compensation unit 3091, the inter prediction parameter supplied from the inter prediction parameter decoding unit 303, and the intra image supplied from the intra prediction image generation unit 310 to perform prediction. An image is generated, and the generated predicted image is supplied to the addition unit 312.

The combining unit 3095 includes a combined intra/inter combining unit 30951, a Triangle combining unit 30952, an OBMC unit 30953, and a BIO unit 30954.

(Combined intra/inter synthesis processing)
The Combined intra/inter combining unit 30951 generates a prediction image by using a unidirectional prediction image in AMVP, a prediction image in the skip mode or the merge prediction mode, and an intra prediction image in combination.

(Triangle composition processing)
The Triangle synthesis unit 30952 generates a prediction image using the above-mentioned Triangle prediction.

(OBMC processing)
The OBMC unit 30953 generates a predicted image using OBMC (Overlapped block motion compensation) processing. The OBMC processing includes the following processing.
Interpolation image (PU interpolation image) generated by using the inter prediction parameter added to the target subblock, and interpolation image (OBMC interpolation image) generated by using the motion parameter of the adjacent subblock of the target subblock Is used to generate an interpolation image (motion compensation image) of the target sub-block.
A predicted image is generated by weighted averaging the OBMC interpolation image and the PU interpolation image.

(BIO processing)
The BIO unit 30954 generates a predicted image by performing BIO (Bi-directional optical flow; bi-prediction gradient change) processing. Details of the BIO unit 30954 will be described later.

(Weight prediction)
In the weight prediction, the motion compensation image PredLX is multiplied by a weight coefficient to generate a prediction image of a block. When one of the prediction list use flags (predFlagL0 or predFlagL1) is 1 (single prediction) and weight prediction is not used, the motion compensation image PredLX (LX is L0 or L1) is adjusted to the pixel bit number bitDepth. I do.

Pred[x][y] = Clip3(0,(1<<bitDepth)-1,(PredLX[x][y]+offset1)>>shift1)
Here, shift1=14-bitDepth and offset1=1<<(shift1-1).
Further, when both of the reference list use flags (predFlagL0 and predFlagL1) are 1 (bi-prediction BiPred) and weight prediction is not used, the motion compensation images PredL0 and PredL1 are averaged and the processing of the following formula is performed to match the pixel bit number. To do.

Pred[x][y] = Clip3(0,(1<<bitDepth)-1,(PredL0[x][y]+PredL1[x][y]+offset2)>>shift2)
Here, shift2=15-bitDepth and offset2=1<<(shift2-1).

Further, when performing uni-prediction and weight prediction, the combining unit 3095 derives the weight prediction coefficient w0 and the offset o0 from the encoded data, and performs the processing of the following formula.

Pred[x][y] = Clip3(0,(1<<bitDepth)-1,((PredLX[x][y]*w0+2^(log2WD-1))>>log2WD)+o0)
Here, log2WD is a variable indicating a predetermined shift amount.

Furthermore, when performing bi-prediction BiPred and weight prediction, the synthesis unit 3095 derives the weight prediction coefficients w0, w1, o0, and o1 from the encoded data, and performs the processing of the following formula.

Pred[x][y] = Clip3(0,(1<<bitDepth)-1,(PredL0[x][y]*w0+PredL1[x][y]*w1+((o0+o1+1)<<log2WD))>>(log2WD+1))
Then, the predicted image of the generated block is output to the addition unit 312.

The inverse quantization/inverse transform unit 311 dequantizes the quantized transform coefficient input from the entropy decoding unit 301 to obtain a transform coefficient. This quantized transform coefficient is obtained by performing frequency transform such as DCT (Discrete Cosine Transform, Discrete Cosine Transform), DST (Discrete Sine Transform, Discrete Sine Transform) on the prediction error and quantized in the coding process. It is a coefficient. The inverse quantization/inverse transform unit 311 performs inverse frequency transform such as inverse DCT and inverse DST on the obtained transform coefficient,
Calculate the prediction error. The inverse quantization/inverse transformation unit 311 outputs the prediction error to the addition unit 312.

The addition unit 312 adds the prediction image of the block input from the prediction image generation unit 308 and the prediction error input from the dequantization/inverse conversion unit 311 for each pixel to generate a decoded image of the block.
The addition unit 312 stores the decoded image of the block in the reference picture memory 306, and also outputs it to the loop filter 305.

(BIO forecast)
Next, details of the prediction (BIO prediction) using the BIO process performed by the BIO unit 30954 will be described. In the bi-prediction mode, the BIO unit 30954 generates a predicted image with reference to the two predicted images (first predicted image and second predicted image) and the gradient correction term.

FIG. 11 is a flowchart illustrating the flow of processing for deriving a predicted image.

The inter prediction parameter decoding unit 303 determines that L0 is unidirectional prediction (in S101, inter_pred_idc
Is 0), the motion compensation unit 3091 generates the L0 predicted image PredL0[x][y] (S102). When the inter prediction parameter decoding unit 303 determines that the prediction is L1 unidirectional prediction (in S101, inter_pred_idc is 1), the motion compensation unit 3091 generates the L1 prediction image PredL1[x][y] (S103). On the other hand, when the inter prediction parameter decoding unit 303 determines that the mode is the bi-prediction mode (in step S101, inter_pred_idc is 2), the process of step S104 below is continued. In S104, the composition unit 3095 determines whether or not BIO processing is necessary by referring to bioAvailableFlag that indicates whether or not to perform BIO processing. When bioAvailableFlag indicates TRUE, the BIO unit 30954 executes BIO processing to generate a bidirectional predicted image (S106). bioAvailableFlag is F
If ALSE is indicated, the combining unit 3095 generates a predicted image by normal bidirectional predicted image generation (S105).

The inter prediction parameter decoding unit 303 may derive TRUE for bioAvailableFlag when the L0 reference image refImgL0 and the L1 reference image refImgL1 are different reference images and the two pictures are in opposite directions with respect to the target picture. .. Specifically, if the target image is currPic, bioAvailableFlag indicates TRUE when the condition of DiffPicOrderCnt(currPic,refImgL0)*DiffPicOrderCnt(currPic,refImgL1)<0 is satisfied.
Here, DiffPicOrderCnt() is the POC (Picture Order Count:
This is a function for deriving the difference in the display order of pictures.

DiffPicOrderCnt(picA,picB) = PicOrderCnt(picA)-PicOrderCnt(picB)
A condition that the motion vector of the target block is not a sub-block unit motion vector may be added as a condition that bioAvailableFlag indicates TRUE.

In addition, as a condition that bioAvailableFlag indicates TRUE, a condition that the motion vector of the current picture is not a motion vector in sub-block units may be added.

Further, as a condition that bioAvailableFlag indicates TRUE, a condition that the sum of absolute differences between the L0 prediction image and the L1 prediction image of two prediction blocks is equal to or more than a predetermined value may be added.

Further, as the condition that bioAvailableFlag indicates TRUE, a condition that the prediction image creation mode is the prediction image creation mode in block units may be added.

The specific contents of the processing performed by the BIO unit 30954 will be described with reference to FIG. The BIO processing unit 30954 includes an L0,L1 predicted image generation unit 309541, a gradient image generation unit 309542, a correlation parameter calculation unit 309543, a motion compensation correction value derivation unit 309544, and a bidirectional predicted image generation unit 309545. There is. The BIO unit 30954 generates a predicted image from the interpolated image received from the motion compensation unit 3091 and the inter prediction parameter received from the inter prediction parameter decoding unit 303, and outputs the generated predicted image to the addition unit 312. From the gradient image, the motion compensation correction value modBIO (motion compensation correction image)
Is derived, and the process of correcting and deriving the predicted images of PredL0 and PredL1 is called bidirectional gradient change processing.

First, the L0,L1 predicted image generation unit 309541 generates L0,L1 predicted images used for BIO processing. The BIO unit 30954 performs BIO processing based on the L0, L1 prediction image for each CU unit or sub CU unit shown in FIG. 13, but in order to obtain the gradient, the target CU or sub CU
The extra interpolation image information for two pixels around is required. The interpolated image information of this portion is generated by using an image with a short tap length such as a Bilinear filter instead of an ordinary interpolation filter for generating a gradient image described later. In other cases, this portion is used as a padding area by copying the surrounding pixels as in the outside of the picture. Also, the unit of BIO processing is NxN pixels of CU unit or less than sub CU unit, and the processing itself is performed using (N+2)x(N+2) pixels with one surrounding pixel added. I do.

The gradient image generation unit 309542 generates a gradient image. In the gradient change (Optical Flow), it is assumed that the pixel value at each point does not change and only the position changes. This is because the change in horizontal pixel value I (horizontal gradient value lx) and its position change Vx, and the change in vertical pixel value I (vertical gradient value ly) and its position change Vy, pixel value I It can be expressed as follows using the time change lt.

lx * Vx + ly * Vy + lt = 0
Hereinafter, the position change (Vx, Vy) will be referred to as the correction weight vector (u, v).

Specifically, the gradient image generation unit 309542 derives the gradient images lx0, ly0, lx1, and ly1 from the following formula. lx0 and lx1 indicate the gradient along the horizontal direction, and ly0 and ly1 indicate the gradient along the vertical direction.

lx0[x][y] = (PredL0[x+1][y]-PredL0[x-1][y])>>4
ly0[x][y] = (PredL0[x][y+1]-PredL0[x][y-1])>>4
lx1[x][y] = (PredL1[x+1][y]-PredL1[x-1][y])>>4
ly1[x][y] = (PredL1[x][y+1]-PredL1[x][y-1])>>4
Then, the correlation parameter calculation unit 309543, using the surrounding 1 pixel for each block of NxN pixels in each CU (N+2) x (N+2) pixel gradient product sum s1, s2, s3, s5, Derive s6.

s1 = sum(phiX[x][y]* phiX[x][y])
s2 = sum(phiX[x][y]* phiY[x][y])
s3 = sum(-theta[x][y]* phiX[x][y])
s5 = sum(phiY[x][y]* phiY[x][y])
s6 = sum(-theta[x][y]* phiY[x][y])
Here, sum(a) represents the sum of a with respect to the coordinates (x, y) in the block of (N+2)x(N+2) pixels. Also,
phiX[x][y] = (lx1[x][y] + lx0[x][y])>>3
phiY[x][y] = (ly1[x][y] + ly0[x][y])>>3
theta[x][y]=(PredL1[x][y]>>6)+(PredL0[x][y]>>6)
Next, the motion compensation correction value derivation unit 30954 derives a correction weight vector (u, v) in NxN pixel units using the derived gradient product sums s1, s2, s3, s5, s6.

u = (s3<<3)>>log2(s1)
v = ((s6<<3)-((((u*s2m)<<12)+u*s2s)>>1))>>log2(s5)
Here, s2m=s2>>12 and s2s=s2&((1<<12)-1).

Note that the range of u and v may be further limited by using clips as described below.

u = s1>0?Clip3(-th,th,-(s3<<3)>>floor(log2(s1))):0
v = s5>0?Clip3(-th,th,((s6<<3)-((((u*s2m)<<12)+u*s2s)>>1))>>floor(log2(s5 ))):0 where th = 1<<(13-bit Depth).

The motion compensation correction value derivation unit 309544 uses the correction weight vector (u, v) in NxN pixel units and the gradient images lx0, ly0, lx1, and ly1 to obtain the motion compensation correction value modBIO[x][y] of NxN pixels. Derive.

modBIO[x][y] = ((lx1[x][y]-lx0[x][y])*u+(ly1[x][y]-ly0[x][y])*v+1) >>1 (Equation A3) or a round function may be used to derive modBIO as follows.

modBIO[x][y] = Round(((lx1[x][y]-lx0[x][y])*u)>>1)+Round(((ly1[x][y]-ly0[ x][y])*v)>>1)
The bidirectional predicted image generation unit 309545 derives the pixel value Pred of the predicted image of NxN pixels using the above parameters and the following formula.

At this time, the bidirectional predicted image generation unit 309545 derives the pixel value Pred of the predicted image of NxN pixels using the above parameters by the following formula.

Pred[x][y] = Clip3(0, (1<<bitDepth)-1,( PredL0[x][y]+PredL1[x][y]+modBIO[x][y]+offset2)>> shift2)
Here, shift2=Max(3,15-bitDepth) and offset2=1<<(shift2-1).

Next, another embodiment of prediction (BIO prediction) using the BIO process performed by the BIO unit 30954 will be described. In the above embodiment, when the pixel bit length and bitDepth are 10 bits, the operation is correct, but in other cases, the calculation accuracy of the gradient image with respect to the encoded pixel bit length is not sufficient, and the encoding efficiency is high. There is a problem that Therefore, by performing the following, when the pixel bit length and the bitDepth are 8 bits or more, the pixel bit length operates in conjunction with the pixel bit length and is within the range of the 32-bit operation.

Specifically, the gradient image generation unit 309542 derives the gradient images lx0, ly0, lx1, and ly1 as follows.

lx0[x][y] = (PredL0[x+1][y]-PredL0[x-1][y])>>shift1
ly0[x][y] = (PredL0[x][y+1]-PredL0[x][y-1])>>shift1
lx1[x][y] = (PredL1[x+1][y]-PredL1[x-1][y])>>shift1
ly1[x][y] = (PredL1[x][y+1]-PredL1[x][y-1])>>shift1
Here, shift1=Max(2,14-bit Depth).

When using the same interpolation filter as HEVC, the values of PredL0 and PredL1 are 8 to 12 for bitDepth.
If it is in the range of bits, the operation precision is 14 bits, and if bitDepth is larger than 12, it becomes (bitDepth+2) bits. In the present embodiment, shift1 that is a value corresponding to bitDepth is shifted to the right to set the calculation accuracy of the gradient images lx0, ly0, lx1, and ly1 to (bitDepth+1) bits.

Next, the correlation parameter calculation unit 309543 derives the gradient product sums s1, s2, s3, s5, s6 for each block of NxN pixels in the CU. Here, s1, s2, s3, s5, s6 are calculated from the sum of the pixels of the block of (N+2)*(N+2) pixels by further using one pixel around the block.

s1 = sum(phiX[x][y]* phiX[x][y])
s2 = sum(phiX[x][y]* phiY[x][y])
s3 = sum(-theta[x][y]* phiX[x][y])
s5 = sum(phiY[x][y]* phiY[x][y])
s6 = sum(-theta[x][y]* phiY[x][y])
Here, sum(a) represents the sum of a with respect to the coordinates (x, y) in the block of (N+2)x(N+2) pixels. Also,
theta[x][y]= -(PredL1[x][y]>>shift4)+(PredL0[x][y]>>shift4)
phiX[x][y] = (lx1[x][y] + lx0[x][y])>>shift5
phiY[x][y] = (ly1[x][y] + ly0[x][y])>>shift5
here,
shift4=Min(8,bitDepth-4)
shift5=Min(5,bitDepth-7)
And

At this time, if the bitDepth of the image is in the range of 8 to 12 bits, the calculation accuracy of the theta value is (19-bitDepth) bits. If the bitDepth of the image is in the range of 8 to 12 bits, the calculation accuracy of phiX and phiY will be 9 bits. Therefore, when N=4, the calculation accuracy of s1, s2, s5, which is the total of the blocks of 6x6 pixels, is about 24 bits if bitDepth is in the range of 8 to 12 bits, and PredL0 and PredL1 Even if the minimum and maximum values are in the 16-bit range, they are within the 32-bit operation range. Similarly, when N=4, the calculation accuracy of s3, s6, which is the total of blocks of 6x6 pixels, is about (34-bit Depth) bits if bitDepth is in the range of 8 to 12 bits. If the minimum and maximum values of PredL0 and PredL1 are in the 16-bit range, it can be realized by 32-bit integer arithmetic.

Supplementally, if bitDepth is in the range of 8 to 12 bits, the accuracy of images PredL0 and PredL1 is 14
Since bits are shift1 = 14-bitDepth, the calculation accuracy of gradient images lx0, ly0, lx1, and ly1 will be bitDepth + 1 from 15 bits of difference between Pred0 and Pred1-(14-bitDepth). bitDepth is 8
, The sum of images with bitDepth + 1 precision lx1[x][y] + lx0[x][y] is bitDepth + 2, and if shift5 = bitDepth-7, then phiX[ The precision of x][y] is 9 bits. The product of phiX[x][y] is 18 bits, and the total of 6x6 blocks (=36, 6 bits) is 24 bits or less. Similarly for theta, the accuracy of PredL1[x][y]>>shift4 is 18-bit Depth and the difference is 19-bit Depth. The product of 19-bit Depth precision theta and 9-bit precision phiX[x][y] is 28-bit Depth. The total of the 6x6 blocks (=36, 6 bits) is 34-bit Depth bits or less.

As another configuration of the correlation parameter calculation unit 309543, the gradient product sum s1, s2, s3, s5, s6 is obtained by a block of NxN pixels instead of a block of (N+2)x(N+2) pixels. Good. In this case, when N=4, the block is 4x4=16 pixels, so the operation bits required to calculate sum are (Ceil(log2(36))-Ceil(log2 (16)) = 2 bits less, so
shift4=Min(7,bitDepth-5)
shift5=Min(4,bitDepth-8)
Even if a value smaller by 1 bit is used for each, it can be realized by a 32-bit integer operation. Also, the amount of calculation of the gradient product sum can be reduced. As shown in FIG. 14, since the unit of BIO processing and the read area match, unlike the case of FIG. 13, a padding area for one pixel around the target CU or sub CU is unnecessary.

Next, the motion compensation correction value derivation unit 309544 derives a correction weight vector (u, v) in NxN pixel units using the derived gradient product sums s1, s2, s3, s5, s6.

u = (s3<<3)>>log2(s1)
v = ((s6<<3)-((((u*s2m)<<12)+u*s2s)>>1))>>log2(s5)
Here, s2m=s2>>12 and s2s=s2&((1<<12)-1).

Note that the range of u and v may be further limited by using clips as described below.

u = s1>0?Clip3(-th,th,-(s3<<3)>>floor(log2(s1))):0
v = s5>0?Clip3(-th,th,((s6<<3)-((((u*s2m)<<12)+u*s2s)>>1))>>floor(log2(s5 ))): 0 here
th = Max(2, 1<<(13-bitDepth))
Is. Since the value of th needs to be calculated in conjunction with shift1, it is necessary to consider the case where the pixel bit length bitDepth is larger than 12 bits.

The motion compensation correction value derivation unit 309544 derives modBIO of the NxN image motion compensation correction value using the correction weight vector (u, v) in NxN pixel units and the gradient images lx0, ly0, lx1, and ly1.

modBIO[x][y] = ((lx1[x][y]-lx0[x][y])*u+(ly1[x][y]-ly0[x][y])*v)>> 1
The bidirectional predicted image generation unit 309545 derives the pixel value Pred of the predicted image in NxN pixel units using the above parameters by the following formula.

Pred[x][y] = Clip3(0, (1<<bitDepth)-1,(PredL0[x][y]+PredL1[x][y]+modBIO[x][y]+offset2)>> shift2)
Here, shift2=Max(3,15-bitDepth) and offset2=1<<(shift2-1).

(Structure of video encoding device)
Next, the configuration of the moving picture coding device 11 according to the present embodiment will be described. FIG. 15 is a block diagram showing the configuration of the moving picture coding device 11 according to the present embodiment. The moving image coding device 11 includes a predicted image generation unit 101, a subtraction unit 102, a conversion/quantization unit 103, an inverse quantization/inverse conversion unit 105, an addition unit 106, a loop filter 107, a prediction parameter memory (prediction parameter storage unit). , A frame memory) 108, a reference picture memory (reference image storage unit, frame memory) 109, a coding parameter determination unit 110, a parameter coding unit 111, and an entropy coding unit 104.

The predicted image generation unit 101 generates a predicted image for each CU that is an area obtained by dividing each picture of the image T. The predicted image generation unit 101 has the same operation as the predicted image generation unit 308 described above, and thus the description thereof will be omitted.

The subtraction unit 102 subtracts the pixel value of the predicted image of the block input from the predicted image generation unit 101 from the pixel value of the image T to generate a prediction error. The subtraction unit 102 outputs the prediction error to the conversion/quantization unit 103.

The transform/quantization unit 103 calculates a transform coefficient by frequency transform for the prediction error input from the subtraction unit 102, and derives a quantized transform coefficient by quantization. The conversion/quantization unit 103
The quantized transform coefficient is output to the entropy coding unit 104 and the inverse quantization/inverse transform unit 105.

The inverse quantization/inverse transform unit 105 is the inverse quantization/inverse transform unit 311 (FIG. 7) in the video decoding device 31.
The description is omitted here. The calculated prediction error is output to the addition unit 106.

The entropy coding unit 104 receives the quantized transform coefficient from the transform/quantization unit 103 and the coding parameter from the parameter coding unit 111. The encoding parameters include, for example, reference picture index refIdxLX, prediction vector index mvp_LX_idx, difference vector mvdLX, motion vector accuracy mode amvr_mode, prediction mode predMode, and merge index merge_idx.

The entropy coding unit 104 entropy-codes the division information, the prediction parameter, the quantized transform coefficient, and the like to generate and output a coded stream Te.

The parameter coding unit 111 includes a header coding unit 1110, a CT information coding unit 1111, and a CU (not shown).
An encoding unit 1112 (prediction mode encoding unit), an inter prediction parameter encoding unit 112, and an intra prediction parameter encoding unit 113 are provided. The CU coding unit 1112 further includes a TU coding unit 1114.

The schematic operation of each module will be described below. The parameter coding unit 111 performs coding processing of parameters such as header information, division information, prediction information, and quantized transform coefficients.

The CT information encoding unit 1111 encodes QT, MT (BT, TT) division information and the like from the encoded data.

The CU encoding unit 1112 encodes CU information, prediction information, TU division flag split_transform_flag, CU residual flags cbf_cb, cbf_cr, cbf_luma, and the like.

The TU encoding unit 1114 encodes the QP update information (quantization correction value) and the quantization prediction error (residual_coding) when the TU includes a prediction error.

The CT information encoding unit 1111 and the CU encoding unit 1112 use inter prediction parameters (prediction mode predMode, merge flag merge_flag, merge index merge_idx, inter prediction identifier inter).
_pred_idc, reference picture index refIdxLX, prediction vector index mvp_LX_idx
, Difference vector mvdLX), intra prediction parameters, quantized transform coefficients, and other syntax elements are supplied to the entropy coding unit 104.

(Structure of inter prediction parameter coding unit)
The parameter coding unit 112 derives an inter prediction parameter based on the prediction parameter input from the coding parameter determination unit 110. The parameter encoding unit 112 includes the same configuration as the configuration in which the inter prediction parameter decoding unit 303 derives the inter prediction parameter.

The configuration of the prediction parameter coding unit 112 will be described. As shown in FIG. 16, the parameter coding control unit 1121, the merge prediction unit 30374, the sub-block prediction unit (affine prediction unit) 30372, the DMVR unit 30375, the MMVD prediction unit 30376, the Triangle prediction unit 30377, the AMVP prediction parameter derivation unit 3032,
The subtraction unit 1123 is included. The merge prediction unit 30374 includes a merge prediction parameter derivation unit 3036. The parameter coding control unit 1121 includes a merge index derivation unit 11211 and a vector candidate index derivation unit 11212. Also, in the parameter coding control unit 1121, the merge index derivation unit 11211 derives merge_idx, affine_flag, base_candidate_idx, distance_idx, direction_idx, etc., and the vector candidate index derivation unit 11212 derives mvpLX, etc. The merge prediction parameter derivation unit 3036, AMVP prediction parameter derivation unit 3032, affine prediction unit 30372, MMVD prediction unit 30376, and Triangle prediction unit 30377 may be collectively referred to as a motion vector derivation unit (motion vector derivation device). The parameter coding unit 112 outputs the motion vector (mvLX, subMvLX), the reference picture index refIdxLX, the inter prediction identifier inter_pred_idc, or information indicating these to the prediction image generation unit 101. In addition, the parameter encoding unit 112, merge_flag, skip_flag, merge_idx, inter_pred_idc, refIdxLX, mvp_lX_idx, mvdLX.
, Amvr_mode, and affine_flag are output to the entropy coding unit 104.

The merge index derivation unit 11211 derives the merge index merge_idx and outputs it to the merge prediction parameter derivation unit 3036 (merge prediction unit). The vector candidate index derivation unit 11212 derives the prediction vector index mvp_lX_idx.

The merge prediction parameter derivation unit 3036 derives an inter prediction parameter based on the merge index merge_idx.

The AMVP prediction parameter derivation unit 3032 derives the prediction vector mvpLX based on the motion vector mvLX. The AMVP prediction parameter derivation unit 3032 outputs the prediction vector mvpLX to the subtraction unit 1123.
The reference picture index refIdxLX and the prediction vector index mvp_lX_idx are output to the entropy coding unit 104.

The affine prediction unit 30372 derives an inter prediction parameter (affine prediction parameter) of the sub block.

The subtraction unit 1123 subtracts the prediction vector mvpLX output from the AMVP prediction parameter derivation unit 3032 from the motion vector mvLX input from the coding parameter determination unit 110 to generate a difference vector mvdLX. The difference vector mvdLX is output to the entropy coding unit 104.

The addition unit 106 adds the pixel value of the prediction image of the block input from the prediction image generation unit 101 and the prediction error input from the inverse quantization/inverse conversion unit 105 for each pixel to generate a decoded image. The addition unit 106 stores the generated decoded image in the reference picture memory 109.

The loop filter 107 applies a deblocking filter to the decoded image generated by the adding unit 106,
Apply SAO and ALF. Note that the loop filter 107 does not necessarily have to include the above three types of filters, and may have a configuration of only a deblocking filter, for example.

The prediction parameter memory 108 stores the prediction parameter generated by the coding parameter determination unit 110 in a predetermined position for each target picture and CU.

The reference picture memory 109 stores the decoded image generated by the loop filter 107 at a predetermined position for each target picture and CU.

The coding parameter determination unit 110 selects one set from among a plurality of sets of coding parameters. The coding parameter is the above-mentioned QT, BT or TT partition information, a prediction parameter, or a parameter to be coded generated in association with these. The predicted image generation unit 101 generates a predicted image using these coding parameters.

The coding parameter determination unit 110 calculates the RD cost value indicating the size of the information amount and the coding error for each of the plurality of sets. The coding parameter determination unit 110 selects a set of coding parameters that minimizes the calculated cost value. As a result, the entropy coding unit 104 outputs the selected set of coding parameters as the coded stream Te. The coding parameter determination unit 110 stores the determined coding parameter in the prediction parameter memory 108.

Note that the moving picture coding device 11 and part of the moving picture decoding device 31 in the above-described embodiment, for example, the entropy decoding unit 301, the parameter decoding unit 302, the loop filter 305, the predicted image generation unit 308, the inverse quantization/inverse. Transforming unit 311, adding unit 312, prediction image generating unit 101, subtracting unit 102, transforming/quantizing unit 103, entropy coding unit 104, dequantizing/inverse transforming unit 105, loop filter 107, coding parameter determining unit 110. The parameter encoding unit 111 may be realized by a computer. In that case, the program for realizing the control function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read by a computer system and executed. The “computer system” referred to here is a computer system built in either the moving image encoding device 11 or the moving image decoding device 31, and includes an OS and hardware such as peripheral devices. Further, the “computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in a computer system. Further, "computer-readable recording medium" means a program that dynamically holds a program for a short time, such as a communication line when transmitting the program through a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory that holds a program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or a client, may be included. Further, the program may be for realizing a part of the above-described functions, and may be a program for realizing the above-mentioned functions in combination with a program already recorded in the computer system.

Further, some or all of the moving picture coding device 11 and the moving picture decoding device 31 in the above-described embodiments may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the moving image encoding device 11 and the moving image decoding device 31 may be individually implemented as a processor, or a part or all of the functional blocks may be integrated and implemented as a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when a technique for forming an integrated circuit that replaces LSI appears with the progress of semiconductor technology, an integrated circuit according to the technique may be used.

Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like without departing from the gist of the present invention. It is possible to

[Application example]
The moving image encoding device 11 and the moving image decoding device 31 described above can be used by being mounted in various devices that perform transmission, reception, recording, and reproduction of moving images. The moving image may be a natural moving image captured by a camera or the like, or an artificial moving image (including CG and GUI) generated by a computer or the like.

First, it will be described with reference to FIG. 2 that the moving image encoding device 11 and the moving image decoding device 31 described above can be used for transmitting and receiving a moving image.

FIG. 2(a) is a block diagram showing the configuration of the transmission device PROD_A equipped with the moving image encoding device 11. As shown in the figure, the transmission device PROD_A is a coding unit PROD_A1 that obtains encoded data by encoding a moving image, and a modulated signal by modulating a carrier wave with the encoded data obtained by the encoding unit PROD_A1. It includes a modulator PROD_A2 for obtaining and a transmitter PROD_A3 for transmitting the modulated signal obtained by the modulator PROD_A2. The moving picture coding device 11 described above is used as this coding unit PROD_A1.

The transmission device PROD_A, as a source of the moving image input to the encoding unit PROD_A1, a camera PROD_A4 that captures the moving image, a recording medium PROD_A5 that records the moving image, an input terminal PROD_A6 for inputting the moving image from the outside, and An image processing unit A7 for generating or processing an image may be further provided. In the drawing, the configuration in which all of these are included in the transmission device PROD_A is illustrated, but some of them may be omitted.

The recording medium PROD_A5 may be a non-encoded moving image recorded, or a moving image encoded by a recording encoding method different from the transmission encoding method may be recorded. It may be one. In the latter case, a decoding unit (decoded between the recording medium PROD_A5 and the encoding unit PROD_A1 for decoding the encoded data read from the recording medium PROD_A5 in accordance with the encoding scheme for recording (
(Not shown) may be interposed.

FIG. 2B is a block diagram showing the configuration of the receiving device PROD_B equipped with the moving image decoding device 31. As shown in the figure, the receiving device PROD_B is a receiving unit PROD_B1 that receives a modulated signal, a demodulating unit PROD_B2 that obtains encoded data by demodulating the modulated signal that the receiving unit PROD_B1 received, and a demodulating unit PROD_B2 And a decoding unit PROD_B3 that obtains a moving image by decoding encoded data. The moving picture decoding device 31 described above is used as this decoding unit PROD_B3.

The receiving device PROD_B has a display PROD_B4 for displaying a moving image, a recording medium PROD_B5 for recording the moving image, and an output terminal for outputting the moving image to the outside as a supply destination of the moving image output by the decoding unit PROD_B3. PROD_B6 may be further provided. In the drawing, the configuration in which the receiving device PROD_B is provided with all of them is illustrated, but a part thereof may be omitted.

The recording medium PROD_B5 may be one for recording a non-encoded moving image, or may be one encoded by a recording encoding method different from the transmission encoding method. May be. In the latter case, an encoding unit (not shown) that encodes the moving image acquired from the decoding unit PROD_B3 according to the recording encoding method may be interposed between the decoding unit PROD_B3 and the recording medium PROD_B5.

The transmission medium that transmits the modulated signal may be wireless or wired.
Further, the transmission mode of transmitting the modulated signal may be broadcast (here, it means a transmission mode in which the transmission destination is not specified in advance) or communication (transmission in which the transmission destination is specified in advance here). Embodiment). That is, the transmission of the modulated signal may be realized by any of wireless broadcasting, wired broadcasting, wireless communication, and wired communication.

For example, a terrestrial digital broadcasting broadcasting station (broadcasting equipment or the like)/receiving station (television receiver or the like) is an example of a transmitting device PROD_A/receiving device PROD_B that transmits and receives modulated signals by wireless broadcasting. Also, a broadcasting station (broadcasting equipment, etc.)/receiving station (television receiver, etc.) of cable television broadcasting is an example of a transmitting device PROD_A/receiving device PROD_B that transmits and receives modulated signals by wired broadcasting.

In addition, a server (workstation, etc.)/client (TV receiver, personal computer, smartphone, etc.) for VOD (Video On Demand) services and video sharing services using the Internet is a transmission device that transmits and receives modulated signals by communication. This is an example of PROD_A/reception device PROD_B (generally, either wireless or wired is used as a transmission medium in LAN, and wired is used as a transmission medium in WAN). Here, the personal computer includes a desktop PC, a laptop PC, and a tablet PC. The smartphone also includes a multifunctional mobile phone terminal.

The client of the moving image sharing service has a function of decoding the encoded data downloaded from the server and displaying it on the display, as well as a function of encoding the moving image captured by the camera and uploading it to the server. That is, the client of the video sharing service functions as both the transmission device PROD_A and the reception device PROD_B.

Next, it will be described with reference to FIG. 3 that the moving image encoding device 11 and the moving image decoding device 31 described above can be used for recording and reproducing a moving image.

FIG. 3(a) is a block diagram showing a configuration of a recording device PROD_C equipped with the above-described moving image encoding device 11. As shown in the figure, the recording device PROD_C includes a coding unit PROD_C1 that obtains coded data by coding a moving image, and a writing unit PROD_C2 that writes the coded data obtained by the coding unit PROD_C1 to a recording medium PROD_M. And are equipped with. The moving picture coding device 11 described above is used as the coding unit PROD_C1.

The recording medium PROD_M may be (1) a type such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) built in the recording device PROD_C, or (2) SD memory. It may be of a type that is connected to the recording device PROD_C, such as a card or a USB (Universal Serial Bus) flash memory, or (3) DVD (Digital Versatile Disc: registered trademark) or BD (Blu-ray). For example, a disc (registered trademark) or the like may be loaded in a drive device (not shown) incorporated in the recording device PROD_C.

Further, the recording device PROD_C has a camera PROD_C3 for capturing a moving image, an input terminal PROD_C4 for inputting the moving image from the outside, and a receiving unit for receiving the moving image as a supply source of the moving image input to the encoding unit PROD_C1. The unit PROD_C5 and the image processing unit PROD_C6 for generating or processing an image may be further provided. In the drawing, the configuration in which the recording device PROD_C is provided with all of them is illustrated, but a part thereof may be omitted.

The receiving unit PROD_C5 may be one that receives an unencoded moving image, or receives encoded data that has been encoded by a transmission encoding method different from the recording encoding method. It may be one that does. In the latter case, a transmission decoding unit (not shown) that decodes the encoded data encoded by the transmission encoding method may be interposed between the reception unit PROD_C5 and the encoding unit PROD_C1.

Examples of such a recording device PROD_C include a DVD recorder, a BD recorder, an HDD (Hard Disk Drive) recorder, and the like (in this case, the input terminal PROD_C4 or the receiving unit PROD_C5 is the main supply source of the moving image). .. In addition, a camcorder (in this case, the camera PROD_C3 is the main source of moving images), a personal computer (in this case, the receiving unit PROD_C5 or the image processing unit C6 is the main source of moving images), a smartphone (this If the camera PROD_C3
(Or the receiving unit PROD_C5 becomes the main source of moving images), etc.
Is an example.

FIG. 3B is a block showing the configuration of the playback device PROD_D equipped with the moving image decoding device 31 described above. As shown in the figure, the reproducing apparatus PROD_D includes a reading unit PROD_D1 that reads the encoded data written in the recording medium PROD_M, and a decoding unit PROD_D2 that obtains a moving image by decoding the encoded data read by the reading unit PROD_D1. , Are provided. The moving picture decoding device 31 described above is used as this decoding unit PROD_D2.

The recording medium PROD_M may be (1) of a type built into the playback device PROD_D, such as a HDD or SSD, or (2) such as an SD memory card or a USB flash memory. It may be of a type that is connected to the playback device PROD_D, or (3) loaded into a drive device (not shown) built in the playback device PROD_D, such as a DVD or BD. Good.

Also, the playback device PROD_D is a display PROD_D3 that displays a moving image, an output terminal PROD_D4 for outputting the moving image to the outside as a supply destination of the moving image output by the decoding unit PROD_D2, and a transmitting unit that transmits the moving image. PROD_D5 may be further provided. In the drawing, a configuration in which the playback device PROD_D is provided with all of them is illustrated, but a part thereof may be omitted.

The transmission unit PROD_D5 may be one that transmits an unencoded moving image, or transmits encoded data that has been encoded by a transmission encoding method different from the recording encoding method. It may be one that does. In the latter case, an encoding unit (not shown) that encodes a moving image with an encoding method for transmission may be interposed between the decoding unit PROD_D2 and the transmission unit PROD_D5.

Examples of such a playback device PROD_D include a DVD player, a BD player, an HDD player, etc. (in this case, the output terminal PROD_D4 to which a television receiver or the like is connected is a main supply destination of the moving image). .. Also, a television receiver (in this case, the display PROD_D3 is the main supply destination of the moving image), digital signage (also called an electronic signboard or electronic bulletin board, etc.), the display PROD_D3 or the transmission unit PROD_D5 is the main supply of the moving image. Desktop PC (in this case, the output terminal PROD_D4 or transmitter PROD_D5 is the main destination of the moving image), laptop or tablet PC (in this case, the display PROD_D3 or transmitter PROD_D5 is a moving image) An example of such a playback device PROD_D is also a smartphone (in which case, the display PROD_D3 or the transmission unit PROD_D5 is the main destination of a moving image), and the like.

(Hardware realization and software realization)
Further, each block of the moving picture decoding device 31 and the moving picture coding device 11 described above may be realized by hardware by a logic circuit formed on an integrated circuit (IC chip), or by a CPU.
It may be realized by software using (Central Processing Unit).

In the latter case, each of the above-mentioned devices has a CPU that executes the instructions of a program that realizes each function, a ROM (Read Only Memory) that stores the above-mentioned program, and a RAM (Random
Access memory), a storage device (recording medium) such as a memory for storing the program and various data. The object of the embodiment of the present invention is to record the program code (execution format program, intermediate code program, source program) of the control program of each device, which is software for realizing the above-described functions, in a computer-readable manner. This can also be achieved by supplying a medium to each of the above devices and causing the computer (or CPU or MPU) to read and execute the program code recorded in the recording medium.

Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks/hard disks, and CD-ROMs (Compact Disc Read-Only Memory)/MO disks (Magneto-Optical discs). )/MD (Mini Disc)/DVD (Digital Versatile Disc: registered trademark)/CD-R (CD Recordable)/Blu-ray
Discs: Discs including optical discs such as registered trademarks, IC cards (including memory cards)
/ Cards such as optical cards, mask ROM/EPROM (Erasable Programmable Read-Only Memory)/EEPROM (Electrically Erasable and Programmable Read-Only Memory: registered trademark)
/Semiconductor memories such as flash ROM, logic circuits such as PLD (Programmable logic device) and FPGA (Field Programmable Gate Array) can be used.

Further, each of the above devices may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited as long as it can transmit the program code. For example, Internet, intranet, extranet, LAN (Local Area Network), ISDN (Integrated Services Digital Network), VAN (Value-Added Network), CATV (Community Antenna television/Cable Television) communication network, virtual private network (Virtual Private Network) Network), telephone network, mobile communication network, satellite communication network, etc. can be used. Further, the transmission medium constituting this communication network may be any medium capable of transmitting the program code, and is not limited to a specific configuration or type. For example, even if wired such as IEEE (Institute of Electrical and Electronic Engineers) 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared rays such as IrDA (Infrared Data Association) and remote control , BlueTooth (registered trademark), IEEE802.11 wireless, HDR (High Data Rate), NFC (Near Field Communication), DLNA (Digital Living Network Alliance: registered trademark), mobile phone network, satellite line, terrestrial digital broadcasting network, etc. It is also available wirelessly. The embodiment of the present invention can also be realized in the form of a computer data signal embedded in a carrier wave, in which the program code is embodied by electronic transmission.

The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

The embodiments of the present invention are preferably applied to a moving image decoding device that decodes encoded data in which image data is encoded, and a moving image encoding device that generates encoded data in which image data is encoded. be able to. Further, it can be suitably applied to the data structure of encoded data generated by the moving image encoding device and referred to by the moving image decoding device.

31 Image decoding device
301 Entropy decoding unit
302 Parameter decoding unit
3020 header decoder
303 Inter prediction parameter decoding unit
304 Intra prediction parameter decoding unit
308 Predicted image generator
309 Inter prediction image generator
310 Intra prediction image generator
311 Inverse quantization/inverse transform unit
312 Adder
11 Image coding device
101 Prediction image generator
102 Subtractor
103 Transform/Quantization unit
104 Entropy encoder
105 Inverse quantization/inverse transform section
107 loop filter
110 Coding parameter determination unit
111 Parameter coding unit
112 Inter prediction parameter coding unit
113 Intra prediction parameter coding unit
1110 Header coding unit
1111 CT information coding unit
1112 CU encoder (prediction mode encoder)
1114 TU encoder
30954 BIO department
309541 L0, L1 prediction image generator
309542 Gradient image generator
309543 Correlation parameter calculator
309544 Motion compensation correction value derivation unit
309545 Bidirectional prediction image generator

Claims (4)

From two interpolated images, having a prediction image generation unit using bidirectional gradient change processing to generate a prediction image by gradient change,
The bidirectional gradient change process is
From the two interpolated images, L0, L1 prediction generation unit for generating L0 prediction image and L1 prediction image for each coding unit,
From the L0 prediction image and the L1 prediction image, the horizontal direction, a gradient image generation unit that generates four gradient images in the vertical direction,
From the product sum operation of the L0 predicted image and L1 predicted image and the four gradient images, a correlation parameter calculation unit that calculates the correlation parameter for each processing unit,
From the correlation parameter, a motion compensation correction value derivation unit that derives a value that corrects the bidirectional prediction image,
A bidirectional predicted image generation unit that generates a predicted image from the motion compensation correction value,
In the gradient image generator and the correlation parameter calculator,
In order to keep the calculation accuracy of the correlation parameter calculation below a certain level,
A moving image decoding device characterized by right-shifting values of an L0 prediction image, an L1 prediction image, and a gradient prediction image according to a pixel bit length. From two interpolated images, having a prediction image generation unit using bidirectional gradient change processing to generate a prediction image by gradient change,
The bidirectional gradient change process is
From the two interpolated images, L0, L1 prediction generation unit for generating L0 prediction image and L1 prediction image for each coding unit,
From the L0 prediction image and the L1 prediction image, the horizontal direction, a gradient image generation unit that generates four gradient images in the vertical direction,
From the product sum operation of the L0 predicted image and L1 predicted image and the four gradient images, a correlation parameter calculation unit that calculates the correlation parameter for each processing unit,
From the correlation parameter, a motion compensation correction value derivation unit that derives a value that corrects the bidirectional prediction image,
A bidirectional predicted image generation unit that generates a predicted image from the motion compensation correction value,
In the correlation parameter calculation unit,
A moving image decoding apparatus, wherein a processing unit for calculating a correlation parameter is a block that is independently divided in a coding unit. From two interpolated images, having a prediction image generation unit using bidirectional gradient change processing to generate a prediction image by gradient change,
The bidirectional gradient change process is
From the two interpolated images, L0, L1 prediction generation unit for generating L0 prediction image and L1 prediction image for each coding unit,
From the L0 prediction image and the L1 prediction image, the horizontal direction, a gradient image generation unit that generates four gradient images in the vertical direction,
From the product sum operation of the L0 predicted image and L1 predicted image and the four gradient images, a correlation parameter calculation unit that calculates the correlation parameter for each processing unit,
From the correlation parameter, a motion compensation correction value derivation unit that derives a value that corrects the bidirectional prediction image,
A bidirectional predicted image generation unit that generates a predicted image from the motion compensation correction value,
In the gradient image generator and the correlation parameter calculator,
In order to keep the calculation accuracy of the correlation parameter calculation below a certain level,
A moving image coding apparatus characterized by right-shifting the values of an L0 prediction image, an L1 prediction image, and a gradient prediction image according to a pixel bit length. From two interpolated images, having a prediction image generation unit using bidirectional gradient change processing to generate a prediction image by gradient change,
The bidirectional gradient change process is
From the two interpolated images, L0, L1 prediction generation unit for generating L0 prediction image and L1 prediction image for each coding unit,
From the L0 prediction image and the L1 prediction image, the horizontal direction, a gradient image generation unit that generates four gradient images in the vertical direction,
From the product sum operation of the L0 predicted image and L1 predicted image and the four gradient images, a correlation parameter calculation unit that calculates the correlation parameter for each processing unit,
From the correlation parameter, a motion compensation correction value derivation unit that derives a value that corrects the bidirectional prediction image,
A bidirectional predicted image generation unit that generates a predicted image from the motion compensation correction value,
In the correlation parameter calculation unit,
A moving picture coding apparatus, wherein a processing unit for calculating a correlation parameter is a block which is independently divided in a coding unit.

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