CN114303379A - Image decoding device, image decoding method, and program - Google Patents

Abstract

In the image decoding apparatus 200 of the present invention, the target blocks are merged, and when the merge list is constructed, even if the motion vector and reference image index corresponding to different merge indexes are the same, when the half-pixel index corresponding to the merge index is different At the same time, it is also registered in the merge list as a different merge index.

Description

Image decoding device, image decoding method, and program

[Technical field]

The present invention relates to an image decoding device, an image decoding method and a program.

[Background technique]

In Non-Patent Document 1, for motion compensated prediction (hereinafter referred to as MC prediction), there are merge coding (hereinafter referred to as merge) and adaptive vector coding (hereinafter referred to as AMVP) for deriving motion vectors ( The technique is hereinafter referred to as mv), and two kinds of interpolation filters for generating the MC predicted image signal using the derived mv are prepared.

The first type is the same interpolation filter as that of Non-Patent Document 2 (hereinafter referred to as HEVC filter), and the second type is the interpolation filter newly introduced in Non-Patent Document 1 (hereinafter referred to as smoothing filter).

Although both are applicable to the case where the reference target of mv is at the position of fractional pixel precision, the above-mentioned smoothing filter is limited to the case where the reference target of mv is at the position of 1/2 pixel precision, and is only applicable to display half-pixel index (hereinafter referred to as the If hpelIfIdx) is valid, the half-pixel index indicates whether the above-mentioned smoothing filter is valid. In other cases, apply the HEVC filter.

When the blocks to be encoded (hereinafter referred to as target blocks) are merged, the above-described hpelIfIdx is inherited from the adjacent blocks that have already been processed, and when the target block is AMVP, the value of hpelIfIdx is determined based on the derived mv.

[Prior Art Literature]

Non-patent literature

Non-Patent Document 1: Versatile Video Coding (Draft 6), JVET-N1001

Non-Patent Document 2: ITU-T H.265 High Efficiency Video Coding

[Content of the Invention]

The problem to be solved by the invention

However, in the above-mentioned prior art, when the object blocks are merged, a specific merge list construction method and a history merge table construction method are used to generate a merge list and a history merge table, and to derive a motion vector, but there are the following problems: In the pruning process in the construction of the merge list and the history merge table, the identity of the half-pixel indices is not confirmed.

Therefore, the present invention has been made in view of the above-mentioned problems, and its object is to provide an image decoding apparatus, an image decoding method, and a program that add a half-pixel index to the judgment condition of the pruning process when constructing a merge list or a history merge table. , to increase the selection opportunity of the smoothing filter, and the result can be expected to improve the coding performance.

means of solving problems

The gist of the first feature of the present invention resides in an image decoding apparatus including: a combining unit configured to decode a motion vector and a half-pixel index based on a combining index, the half-pixel index indicating whether the motion vector refers to 1/ 2-pixel precision position; a motion vector refinement unit configured to refine the motion vector through MMVD (Merge Motion Vector Difference) or DMVR (Decoder-side Motion Vector Refinement); a filter determination unit configured to The refined motion vector and the half-pixel index are used to determine whether to use an interpolation filter and an interpolation filter type; and a filter application unit is configured to use the interpolation filter to generate a motion-compensated prediction pixel signal; In addition, the merging unit is configured to generate a merging list by a specific merging list construction method, decode the motion vector and the half-pixel index based on the merging list and the merging index, and merge the target block , the merging unit is configured to, when constructing the merging list, even if the motion vector and reference image index corresponding to the different merging indices are the same, when the half-pixel indices corresponding to the merging indices are different, they are also regarded as different The merge index of is registered in the merge list.

The gist of the second feature of the present invention resides in an image decoding apparatus including: a combining unit configured to decode a motion vector and a half-pixel index based on a combining index, the half-pixel index indicating whether the motion vector refers to 1/ 2-pixel precision position; a motion vector refinement unit configured to refine the motion vector through MMVD (Merge Motion Vector Difference) or DMVR (Decoder-side Motion Vector Refinement); a filter determination unit configured to The refined motion vector and the half-pixel index are used to determine whether to use an interpolation filter and an interpolation filter type; and a filter application unit is configured to use the interpolation filter to generate a motion-compensated prediction pixel signal; In addition, the merging unit is configured to generate a merging list by a specific merging list construction method, decode the motion vector and the half-pixel index based on the merging list and the merging index, and merge the target block , the merging unit is configured to, when constructing the history merging table, even if the motion vector and reference image index corresponding to the different history merging candidates are the same, when the half-pixel indices corresponding to the history merging candidates are different, they are also regarded as different The history merge candidates are registered in the history merge table.

The gist of the third feature of the present invention resides in an image decoding apparatus including: a combining unit configured to decode a motion vector and a half-pixel index based on a combining index, the half-pixel index indicating whether the motion vector refers to 1/ 2-pixel precision position; a motion vector refinement unit configured to refine the motion vector through MMVD (Merge Motion Vector Difference) or DMVR (Decoder-side Motion Vector Refinement); a filter determination unit configured to The refined motion vector and the half-pixel index are used to determine whether to use an interpolation filter and an interpolation filter type; and a filter application unit is configured to use the interpolation filter to generate a motion-compensated prediction pixel signal; In addition, the merging unit is configured to generate a merging list by a specific merging list construction method, decode the motion vector and the half-pixel index based on the merging list and the merging index, and merge the target block , the merging unit is configured to use the half-pixel index of the reference block and register it in the merging list when registering the merging index of the temporal merging in the merging list.

The gist of the fourth feature of the present invention is an image decoding method, comprising: step A, decoding a motion vector and a half-pixel index according to a merge index, the half-pixel index indicating whether the motion vector refers to 1/2 pixel Precision position; Step B, through MMVD (Merge Motion Vector Difference) or DMVR (Decoder-side Motion Vector Refinement), refine the motion vector; Step C, based on the refined motion vector and the half pixel index, to determine whether to use an interpolation filter and the type of interpolation filter; and step D, to use the interpolation filter to generate a motion-compensated prediction pixel signal; and, in the step A, to pass a specific merge list The construction method is to generate a merge list, and decode the motion vector and the half-pixel index according to the merge list and the merge index, and the target blocks are merged. When constructing the merge list, the merging unit: Even if the motion vector and reference image index corresponding to the different merging indexes are the same, when the half-pixel indices corresponding to the merging indexes are different, they are registered in the merging list as different merging indexes.

The gist of a fifth feature of the present invention resides in a program for causing a computer to function as an image decoding apparatus including a combining unit configured to decode a motion vector and a half-pixel index based on a combining index, the The half-pixel index indicates whether the motion vector refers to a 1/2 pixel precision position; the motion vector refinement part is configured to refine the motion vector through MMVD (Merge Motion Vector Difference) or DMVR (Decoder-side Motion Vector Refinement). a filter determination unit configured to determine whether to use an interpolation filter and an interpolation filter type based on the refined motion vector and the half-pixel index; and a filter application unit configured to use the interpolation A filter is used to generate a motion-compensated predicted pixel signal; and the combining unit is configured to generate a combining list by using a specific combining list construction method, and to perform a combination of the motion vector and the all combining list based on the combining list and the combining index. The half-pixel index is decoded, and the target block is merged, and the merging unit is configured such that, when constructing the merge list, even if the motion vector and reference image index corresponding to the different merge index are the same, when the merge index is the same as the merge index When the corresponding half-pixel indices are different, they are also registered in the merging list as different merging indices.

effect of invention

According to the present invention, it is possible to provide an image decoding apparatus, an image decoding method, and a program, in which the determination of the half-pixel index is added to the determination condition of the pruning process when the merge list is constructed or the history merge table is added, thereby increasing the smoothing filter. Opportunities are chosen, and as a result an improvement in coding performance can be expected.

[Simple Description of Drawings]

FIG. 1 is a diagram showing an example of the configuration of an image processing system 1 according to an embodiment.

FIG. 2 is a diagram showing an example of functional blocks of the image coding apparatus 100 according to the embodiment.

FIG. 3 is a diagram showing an example of functional blocks of the inter prediction unit 111 of the image coding apparatus 100 according to the embodiment.

FIG. 4 is a diagram showing an example of functional blocks of the image decoding apparatus 200 according to an embodiment.

FIG. 5 is a diagram showing an example of functional blocks of the inter prediction unit 241 of the image decoding apparatus 200 according to the embodiment.

FIG. 6 is a flowchart showing an example of a process of determining whether or not to apply an interpolation filter and a filter type in the filter determination unit 111D1/241C1 according to an embodiment.

FIG. 7 is a flowchart showing an example of a half pixel index (hpelIfIdx) determination process according to an embodiment.

FIG. 8 is a diagram for explaining the determination process of Non-Patent Document 1. FIG.

FIG. 9 is a diagram showing an example of functional blocks of the mv refinement unit 241B of the image decoding apparatus 200 according to the embodiment.

FIG. 10 is a flowchart showing an example of a merge list construction process according to an embodiment.

FIG. 11 is a diagram showing an example of a merged list generated by a merged list construction process according to an embodiment.

FIG. 12 is a diagram showing an example of space combining according to an embodiment.

FIG. 13 is a diagram showing an example of time integration according to an embodiment.

FIG. 14 is a diagram for explaining an example of scaling processing of motion vectors in temporal combining according to an embodiment.

FIG. 15 is a diagram showing an example of history merging in one embodiment.

FIG. 16 is a diagram showing an example of a combination of a new motion vector and half-pixel index calculated by pairwise average combining according to an embodiment.

FIG. 17 is a flowchart showing an example of a process of setting a new half-pixel index generated by pairwise average combining according to an embodiment.

FIG. 18 is a diagram showing an example of constructing a merged list according to an embodiment.

[Detailed ways]

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the components in the following embodiments can be appropriately replaced with existing components and the like, and various modifications including combinations with other existing components can be made. Therefore, the content of the invention described in the claims should not be limited by the description of the following embodiments.

<First Embodiment>

Next, the image processing system 10 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 28 . FIG. 1 is a diagram showing an image processing system 10 according to the present embodiment.

As shown in FIG. 1 , the image processing system 10 according to the present embodiment includes an image encoding device 100 and an image decoding device 200 .

The image encoding device 100 is configured to generate encoded data by encoding an input image signal. The image decoding device 200 is configured to generate an output image signal by decoding the encoded data.

The encoded data may be transmitted from the image encoding device 100 to the image decoding device 200 via the transmission path. The encoded data may be supplied from the image encoding device 100 to the image decoding device 200 after being stored in a storage medium.

(image encoding device 100 )

Next, the image coding apparatus 100 according to the present embodiment will be described with reference to FIG. 2 . FIG. 2 is a diagram showing an example of functional blocks of the image coding apparatus 100 according to the present embodiment.

As shown in FIG. 2 , the image coding apparatus 100 includes an inter prediction unit 111, an intra prediction unit 112, a subtractor 121, an adder 122, a transform and quantization unit 131, an inverse transform and inverse quantization unit 132, an encoding unit 140, a loop The channel filter processing unit 150 and the frame buffer 160 .

The inter-frame prediction unit 111 is configured to generate a prediction signal by inter-frame prediction.

Specifically, the inter prediction unit 111 is configured to designate a reference block included in the reference frame by comparing a frame to be encoded (hereinafter referred to as a target frame) with a reference frame stored in the frame buffer 160, and to determine The motion vector (mv) of the specified reference block.

In addition, the inter prediction unit 111 is configured to generate, for each target block, a prediction signal included in an encoding target block (hereinafter referred to as a target block) based on the reference block and the motion vector. The inter prediction unit 111 is configured to output the prediction signal to the subtractor 121 and the adder 122 . Here, the reference frame is a frame different from the object frame.

The intra-frame prediction unit 112 is configured to generate a prediction signal by intra-frame prediction.

Specifically, the intra prediction unit 112 is configured to designate a reference block included in the target frame, and to generate a prediction signal for each target block based on the designated reference block. In addition, the intra prediction unit 112 is configured to output the prediction signal to the subtractor 121 and the adder 122 .

Here, the reference block is the block to which the object block refers. For example, the reference block is a block adjacent to the object block.

The subtractor 121 is configured to subtract the prediction signal from the input image signal, and output the prediction residual signal to the transform and quantization unit 131 . Here, the subtractor 121 is configured to generate a prediction residual signal which is a difference between the prediction signal generated by intra prediction or inter prediction and the input image signal.

The adder 122 is configured to add the prediction signal and the prediction residual signal output from the inverse transform and inverse quantization unit 132 to generate a pre-filtering decoded signal, and output the pre-filtering decoded signal to the intra prediction unit 112 and the loop. The channel filter processing unit 150 .

Here, the decoded signal before the filtering process constitutes a reference block used in the intra prediction unit 112 .

The transform and quantization unit 131 is configured to perform transform processing of the prediction residual signal and obtain coefficient level values. Furthermore, the transform and quantization unit 131 may be configured to perform quantization of coefficient level values.

Here, the conversion process is a process of converting the prediction residual signal into a frequency component signal. In this transformation process, a base model (transformation matrix) corresponding to discrete cosine transform (DCT, Discrete Cosine Transform) may be used, or a base model (transformation matrix) corresponding to discrete sine transform (DST, Discrete Sine Transform) may be used. .

The inverse transform and inverse quantization unit 132 is configured to perform inverse transform processing of the coefficient level values output from the transform and quantization unit 131 . Here, the inverse transform and inverse quantization unit 132 may be configured to perform inverse quantization of the coefficient level values before the inverse transform process.

Here, inverse transform processing and inverse quantization are performed in the reverse order of the transform processing and quantization performed by the transform and quantization unit 131 .

The encoding unit 140 is configured to encode the coefficient level values output from the transform and quantization unit 131, and to output encoded data.

Here, for example, the encoding is entropy encoding in which codes of different lengths are allocated based on the generation probability of coefficient level values.

In addition, the encoding unit 140 is configured to encode not only the coefficient level values, but also control data used in the decoding process.

Here, the control data may include size data such as a coding block (CU, Coding Unit) size, a prediction block (PU, Prediction Unit) size, and a transform block (TU, Transform Unit) size.

In addition, as described below, the control data may also include header information such as a sequence parameter set (SPS, Sequence Parameter Set), a picture parameter set (PPS, Picture Parameter Set), and a slice header.

The loop filter processing unit 150 is configured to perform filtering processing on the pre-filtered decoded signal output from the adder 122 and output the post-filtered decoded signal to the frame buffer 160 .

Here, for example, the filtering process is a deblocking filtering process that reduces distortion generated at boundary portions of blocks (encoding blocks, prediction blocks, or transform blocks).

The frame buffer 160 is configured to store reference frames used in the inter prediction unit 111 .

Here, the decoded signal after the filtering process constitutes a reference frame used in the inter prediction unit 111 .

As shown in FIG. 2 , the image coding apparatus 100 includes an inter prediction unit 111, an intra prediction unit 112, a subtractor 121, an adder 122, a transform and quantization unit 131, an inverse transform and inverse quantization unit 132, an encoding unit 140, a loop The channel filter processing unit 150 and the frame buffer 160 .

The inter-frame prediction unit 111 is configured to generate a prediction signal by inter-frame prediction.

Specifically, the inter prediction unit 111 is configured to designate a reference block included in the reference frame by comparing a frame to be encoded (hereinafter referred to as a target frame) with a reference frame stored in the frame buffer 160, and to determine The motion vector (mv) of the specified reference block.

In addition, the inter prediction unit 111 is configured to generate, for each target block, a prediction signal included in an encoding target block (hereinafter referred to as a target block) based on the reference block and the motion vector. The inter prediction unit 111 is configured to output the prediction signal to the subtractor 121 and the adder 122 . Here, the reference frame is a frame different from the object frame.

The intra-frame prediction unit 112 is configured to generate a prediction signal by intra-frame prediction.

Specifically, the intra prediction unit 112 is configured to designate a reference block included in the target frame, and to generate a prediction signal for each target block based on the designated reference block. In addition, the intra prediction unit 112 is configured to output the prediction signal to the subtractor 121 and the adder 122 .

Here, the reference block is the block to which the object block refers. For example, the reference block is a block adjacent to the object block.

The subtractor 121 is configured to subtract the prediction signal from the input image signal, and output the prediction residual signal to the transform and quantization unit 131 . Here, the subtractor 121 is configured to generate a prediction residual signal which is a difference between the prediction signal generated by intra prediction or inter prediction and the input image signal.

The adder 122 is configured to add the prediction signal and the prediction residual signal output from the inverse transform and inverse quantization unit 132 to generate a pre-filtering decoded signal, and output the pre-filtering decoded signal to the intra prediction unit 112 and the loop. The channel filter processing unit 150 .

Here, the decoded signal before the filtering process constitutes a reference block used in the intra prediction unit 112 .

The transform and quantization unit 131 is configured to perform transform processing of the prediction residual signal and obtain coefficient level values. Furthermore, the transform and quantization unit 131 may be configured to perform quantization of coefficient level values.

Here, the conversion process is a process of converting the prediction residual signal into a frequency component signal. In this transformation process, a base model (transformation matrix) corresponding to discrete cosine transform (DCT, Discrete Cosine Transform) may be used, or a base model (transformation matrix) corresponding to discrete sine transform (DST, Discrete Sine Transform) may be used. .

The inverse transform and inverse quantization unit 132 is configured to perform inverse transform processing of the coefficient level values output from the transform and quantization unit 131 . Here, the inverse transform and inverse quantization unit 132 may be configured to perform inverse quantization of the coefficient level values before the inverse transform process.

Here, inverse transform processing and inverse quantization are performed in the reverse order of the transform processing and quantization performed by the transform and quantization unit 131 .

The encoding unit 140 is configured to encode the coefficient level values output from the transform and quantization unit 131, and to output encoded data.

Here, for example, the encoding is entropy encoding in which codes of different lengths are allocated based on the generation probability of coefficient level values.

In addition, the encoding unit 140 is configured to encode not only the coefficient level values, but also control data used in the decoding process.

Here, the control data may include size data such as a coding block (CU, Coding Unit) size, a prediction block (PU, Prediction Unit) size, and a transform block (TU, Transform Unit) size.

In addition, as described below, the control data may also include header information such as a sequence parameter set (SPS, Sequence Parameter Set), a picture parameter set (PPS, Picture Parameter Set), and a slice header.

The loop filter processing unit 150 is configured to perform filtering processing on the pre-filtered decoded signal output from the adder 122 and output the post-filtered decoded signal to the frame buffer 160 .

Here, for example, the filtering process is a deblocking filtering process that reduces distortion generated at boundary portions of blocks (encoding blocks, prediction blocks, or transform blocks).

The frame buffer 160 is configured to store reference frames used in the inter prediction unit 111 .

Here, the decoded signal after the filtering process constitutes a reference frame used in the inter prediction unit 111 .

(Inter prediction unit 111 )

Next, the inter prediction unit 111 of the image coding apparatus 100 according to the present embodiment will be described with reference to FIG. 3 . FIG. 3 is a diagram showing an example of functional blocks of the inter prediction unit 111 of the image coding apparatus 100 according to the present embodiment.

As shown in FIG. 3 , the inter prediction unit 111 includes an mv derivation unit 111A, an AMVR (Adaptive Motion Vector Resolution) unit 111B, an mv refinement unit 111B, and a prediction signal generation unit 111D.

The inter prediction unit 111 is an example of a prediction unit configured to generate a prediction signal included in a target block based on a motion vector.

As shown in FIG. 3 , the mv derivation unit 111A includes an AMVP (Adaptive Motion Vector Prediction) unit 111A1 and a combining unit 111A2 , and acquires a motion vector using the target frame and reference frame from the frame buffer 160 as inputs.

The AMVP unit 111A1 is configured to designate a reference block included in the reference frame by comparing the target frame with the reference frame, and to search for the motion vector of the designated reference block.

Then, the above-described search process is performed on a plurality of candidate reference frames to identify reference frames and motion vectors for prediction in the target block, and output them to the prediction signal generation unit 111D in the subsequent stage.

Up to two reference frames and motion vectors can each be used for a block. The case of using only one set of reference frames and motion vectors for one block is called "unidirectional prediction", and the case of using two sets of reference frames and motion vectors is called "bidirectional prediction". Hereinafter, the first group will be referred to as "L0", and the second group will be referred to as "L1".

In addition, in order to reduce the amount of coding when the motion vector identified above is finally transmitted to the decoding device, the AMVP unit 111A selects motion vector predictor (mvp, motion vector predictor) candidates from motion vector predictor (mvp, motion vector predictor) candidates derived from adjacent coded motion vectors , and select the mvp with the smaller motion vector difference (mvd, motion vector difference), which is the difference with the motion vector of the target block.

An index indicating the mvp and mvd selected in this way and an index indicating a reference frame (hereinafter referred to as Refidx) are encoded by the encoding unit 140 and transmitted to the image decoding device 200 . This process is generally referred to as Adaptive Motion Vector Prediction Coding (AMVP, Adaptive Motion Vector Prediction).

The above-mentioned search method for motion vector, method for determining reference frame and motion vector, method for selecting mvp, and method for calculating mvd may be known methods, and therefore detailed descriptions thereof will be omitted.

The AMVR unit 111B has a function of AMVR (Adaptive Motion Vector Resolution) for changing the transmission accuracy of the mvd calculated by the AMVP unit 111A.

Since mvd is derived from the sum of the motion vector of the target block and mvp as described above, changing the transmission accuracy of mvd means changing the accuracy of the motion vector itself of the target block.

In Non-Patent Document 1, there are three variations in the transmission accuracy of the AMVR-based mvd. Usually the transmission precision of mvd is 1/16 pixel precision. At this time, the motion vector will eventually refer to the position of 1/16 pixel precision, but when AMVR is valid, the transmission precision of mvd is selected from 1/4 pixel precision, 1/2 pixel precision Pixel precision, 1 pixel precision (ie integer pixel precision).

However, when the object block is affine, the transmission precision of mvd is selected from 1/4 pixel precision, 1/16 pixel precision, 1 pixel precision. Here, affine refers to Affine of Non-Patent Document 1.

In addition, in Non-Patent Document 1, only when 1/2 pixel accuracy is selected as the transmission accuracy of the mvd, the prediction signal generation unit 111D in the latter stage selects and selects other than the 1/2 pixel accuracy. The pixel precision when applying the interpolation filter differs from the interpolation filter. Details will be described below.

Then, when the AMVR unit 111B determines that the AMVR process is valid, a flag indicating that the AMVR is valid and an index indicating the precision to which the mvd is corrected by the AMVR are transmitted to the image decoding device 200 .

The merging unit 111A2 does not search and derive motion information of the target block like the AMVP unit 111A1 does, and does not transmit the difference mvd with the adjacent block, but takes the target frame and the reference frame as input, and the target block is in the same frame as the target block. The adjacent block in the frame or the block at the same position in the frame different from the target frame is used as the reference block, and the motion information of the reference block is directly used. This process is generally referred to as merge encoding (hereinafter referred to as merge).

When the object block is merged, a merge list for the object block is first created. The merge list is a list listing the combinations of multiple reference frames and motion vectors. An index (hereinafter referred to as a merge index) is assigned to each combination, and only the above-mentioned merge index is encoded and transmitted to the image decoding apparatus 200 instead of separately encoding the Refidx and motion vector information.

Here, by sharing the merge list creation method on the image coding apparatus 100 side and the image decoding apparatus 200 side in advance, the image decoding apparatus 200 side can decode Refidx and motion vector information only from the merge index information. Details of the method of creating the merged list will be described later.

The mv thinning unit 111C is configured to perform thinning processing of correcting the motion vector output from the combining unit 111A2. Details will be described below.

The predicted signal generation unit 111D is configured to take a motion vector as an input and output an MC predicted image signal, and includes a filter determination unit 111D1 and a filter application unit 111D2.

The filter determination unit 111D1 determines whether to apply an interpolation filter and a filter type based on the motion vector. Details will be described below.

The filter application unit 111D2 is configured to generate a prediction signal based on the selected interpolation filter, motion vector, and reference frame when the filter determination unit 111D1 determines that the interpolation filter is valid.

When the filter determination unit 111D1 determines that the interpolation filter is invalid, the interpolation filter is not used, and a prediction signal is generated based on the motion vector and the reference frame.

(image decoding device 200 )

Next, the image decoding apparatus 200 according to the present embodiment will be described with reference to FIG. 4 . FIG. 4 is a diagram showing an example of functional blocks of the image decoding apparatus 200 according to the present embodiment.

As shown in FIG. 4 , the image decoding apparatus 200 includes a decoding unit 210 , an inverse transform and inverse quantization unit 220 , an adder 230 , an inter prediction unit 241 , an intra prediction unit 242 , a loop filter processing unit 250 , and a frame buffer 260 .

The decoding unit 210 is configured to decode the encoded data generated by the image encoding device 100 and to decode the coefficient level value.

Here, for example, the decoding is entropy decoding in the reverse order of the entropy encoding performed by the encoding unit 140 .

Furthermore, the decoding unit 210 may be configured to acquire the control data by decoding the encoded data.

In addition, as described above, the control data may include size data such as encoding block size, prediction block size, transform block size, and the like.

The inverse transform and inverse quantization unit 220 is configured to perform inverse transform processing of the coefficient level value output from the decoding unit 210 . Here, the inverse transform and inverse quantization unit 220 may be configured to perform inverse quantization of the coefficient level values before the inverse transform process.

Here, inverse transform processing and inverse quantization are performed in the reverse order of the transform processing and quantization performed by the transform and quantization unit 131 .

The adder 230 is configured to add the prediction signal and the prediction residual signal output from the inverse transform and inverse quantization unit 220 to generate a pre-filtering decoded signal, and output the pre-filtering decoded signal to the intra prediction unit 242 and the loop Filter processing unit 250 .

Here, the decoded signal before the filtering process constitutes a reference block used in the intra prediction unit 242 .

Like the inter-frame prediction unit 111 , the inter-frame prediction unit 241 is configured to generate a prediction signal by inter-frame prediction (interframe prediction).

Specifically, the inter prediction unit 241 is configured to generate a prediction signal for each prediction block based on the motion vector decoded from the encoded data and the reference signal included in the reference frame. The inter prediction unit 241 is configured to output the prediction signal to the adder 230 .

Like the intra-frame prediction unit 112, the intra-frame prediction unit 242 is configured to generate a prediction signal by intra-frame prediction (intraframe prediction).

Specifically, the intra prediction unit 242 is configured to designate a reference block included in the target frame, and to generate a prediction signal for each prediction block based on the designated reference block. The intra prediction unit 242 is configured to output the prediction signal to the adder 230 .

Like the loop filter processing unit 150 , the loop filter processing unit 250 is configured to perform filtering processing on the pre-filtered decoded signal output from the adder 230 and output the post-filtered decoded signal to the frame buffer 260 .

Here, the filtering process is, for example, a deblocking filtering process that reduces distortion generated at boundary portions of blocks (encoding blocks, prediction blocks, transform blocks, or sub-blocks obtained by dividing them).

Like the frame buffer 160 , the frame buffer 260 is configured to store reference frames used by the inter prediction unit 241 .

Here, the decoded signal after the filtering process constitutes a reference frame used in the inter prediction unit 241 .

(Inter prediction unit 241)

Next, the inter prediction unit 241 of the present embodiment will be described with reference to FIG. 5 . FIG. 5 is a diagram showing an example of functional blocks of the inter prediction unit 241 according to the present embodiment.

As shown in FIG. 5 , the inter prediction unit 241 includes an mv decoding unit 241A, an mv refinement unit 241B, and a prediction signal generation unit 111C.

The inter prediction unit 241 is an example of a prediction unit configured to generate a prediction signal included in a prediction block based on a motion vector.

The mv decoding unit 241A includes an AMVP unit 241A1 and a combining unit 241A2, and obtains a motion vector by decoding the target frame and reference frame input from the frame buffer 260 and control data received from the image coding device 100 .

The AMVP unit 241A1 is configured to receive the target frame and the reference frame, the indices representing mvp and mvd, Refidx from the image coding apparatus 100 , and the index representing the transmission accuracy of mvd from the AMVR unit 111B to decode the motion vector. As for the decoding method of the motion vector, a known method can be adopted, and therefore, a detailed description thereof is omitted.

The merging unit 241A2 is configured to receive the merging index from the image encoding device 100 to decode the motion vector.

Specifically, the merging unit 241A2 is configured to construct a merging list by the same method as that of the image coding apparatus 100, and acquire a motion vector corresponding to the received merging index from the constructed merging list. Details of the method of constructing the merged list will be described later.

Like the thinning unit 111C, the mv thinning unit 241B is configured to execute a thinning process for correcting a motion vector.

The predicted signal generation unit 241C is configured to include a filter determination unit 241C1 and a filter application unit 241C2, and similarly to the predicted signal generation unit 111C, generates a predicted signal based on a motion vector.

In addition, the filter determination unit 241C1 of the image decoding device 200 has exactly the same configuration as the filter determination unit 111D1 of the image encoding device 100. Therefore, in the present embodiment, the operation of the filter determination unit 111D1 is hereinafter performed as a representative. illustrate.

(judgment processing of interpolation filter)

Next, referring to FIG. 6 , the process of determining whether to apply an interpolation filter and a filter type in the filter determination unit 111D1/241C1 of the present embodiment will be described.

FIG. 6 is a flowchart showing an example of a processing procedure for determining whether to apply an interpolation filter and a filter type in the filter determining unit 111D1 of the present embodiment.

As shown in FIG. 6, in step S6-1, the filter determination part 111D1 determines whether the reference position of mv is a decimal pixel position. When the reference position of mv is a decimal pixel position, the process proceeds to step S6-2, and when the reference position of mv is not a decimal pixel position, that is, when the reference position of mv is an integer pixel value position, the process proceeds to step S6- 3.

In step S6-2, the filter determination unit 111D1 determines that the interpolation filter is applied, and the process proceeds to step S6-4.

In step S6-3, the filter determination unit 111D1 determines that the interpolation filter is not to be applied, and ends this process.

In step S6-4, the filter determination unit 111D1 determines whether the following half pixel index (hpelIfIdx) is invalid, that is, whether it is "0". When hpelIfIdx is "0", the process proceeds to step S6-5, and when hpelIfIdx is valid, that is, not "0", the process proceeds to step S6-6.

In step S6-5, the filter determination unit 111D1 determines that the HEVC filter is to be used as the interpolation filter, and ends this process.

Here, the HEVC filter refers to the same 8-tap linear interpolation filter as in Non-Patent Document 2.

In step S6-6, the filter determination unit 111D1 determines to use a smoothing filter as an interpolation filter.

Here, for example, the 6-tap Gaussian filter employed in Non-Patent Document 1 can be used as the smoothing filter. Furthermore, it is also possible to set a plurality of filters to be used as interpolation filters according to the value indicated by hpelIfIdx.

In this way, when the reference position of mv is a fractional pixel position, it is possible to adaptively switch between two or more interpolation filters based on hpelIfIdx. Therefore, the interpolation filter to be used can be selected according to the image characteristics, As a result, the effect of improving the encoding performance can be expected.

(Setting process of half pixel index (hpelIfIdx))

Next, the determination process of the half pixel index (hpelIfIdx) according to the present embodiment will be described with reference to FIG. 7 .

FIG. 7 is a flowchart showing an example of the procedure of determination processing of hpelIfIdx in the filter determination unit 111D1 of the present embodiment.

As described above, hpelIfIdx is related to the determination of the interpolation filter type, and when hpelIfIdx is "0", that is, invalid, the same interpolation filter as in Non-Patent Document 2 is used. On the other hand, when hpelIfIdx is not "0", that is, when it is valid, the smoothing filter is used.

When the object block is merged, hpelIfIdx simultaneously obtains the motion vector and RefIdx from the reference block, and corresponds to the merge index.

On the other hand, when the target block is not in merge mode and the motion vector is decoded by AMVP, the value of hpelIfIdx is determined based on whether or not AMVR is applied and the specific conditions described above.

As shown in FIG. 7, in step S7-1, the filter determination part 111D1 determines whether AMVR is valid. At the time of determination, for example, similarly to Non-Patent Document 1, it may be determined by decoding a flag (amvr_flag) indicating whether or not AMVR is applied.

When it is determined in step S7-1 that the AMVR is valid, the process proceeds to step S7-2, and when it is determined that the AMVR is invalid, the process proceeds to step S7-3.

In step S7 - 2 , the filter determination unit 111D1 determines whether or not the value of hpelIfIdx is “0” based on the specific condition 1 .

When it is determined in step S7-2 that the specific condition 1 is satisfied, the process proceeds to step S7-4, and when it is determined that the specific condition 1 is not satisfied, the process proceeds to step S7-5.

Here, in the specific condition 1 of step S7-2, it can be determined by decoding the index (amvr_precision_idx) indicating the transmission precision of the AMVR, and when the transmission precision of the AMVR is 1/2 pixel precision, it is determined that the specific condition 1 is satisfied , otherwise, it is judged that the specific condition 1 is not met.

In addition, in the specific condition 1 of step S7-2, it can also be judged by whether the target block is affine, when the target block is affine, it is judged that the specific condition 1 is not satisfied, and when the target block is not affine, And when amvr_precision_idx indicates that the transmission precision of mvd is 1/2 pixel precision, it is determined that the specific condition 1 is satisfied.

Here, affine refers to Affine used in Non-Patent Document 1, and since a known method can be used in the present invention, the description thereof is omitted.

In addition, in the specific condition 1 of step S7-2, it can also be judged by whether the target block is an IBC, when the target block is an IBC, it is judged that the specific condition 1 is not satisfied, when the target block is not an IBC, and when amvr_precision_idx indicates When the transmission accuracy of mvd is 1/2 pixel accuracy, it is determined that the specific condition 1 is satisfied.

Here, the IBC refers to the IBC (Intra_Block_Copy) used in Non-Patent Document 1, and a known method can be used in the present invention, so the description thereof is omitted.

In step S7-3, the filter determination unit 111D1 determines that hpelIfIdx is "0", and ends this process.

In step S7-4, the filter determination unit 111D1 determines that hpelIfIdx is "1", and ends this process.

In step S7-5, the filter determination unit 111D1 determines that hpelIfIdx is "0", and ends the present process.

In addition, the determination process of hpelIfIdx has been described with the flowchart so far, but the filter determination unit 111D1 may be based on the decoding results of amvr_flag, amvr_precision_idx, inter_Affine_flag, and Whether the object block is an IBC, the Avmrshift value is determined, and the value of hpelIfIdx is determined according to the AMVR_shift value.

(mv refinement section)

Next, the mv refinement unit 241B of the present embodiment will be described with reference to FIG. 9 . In addition, since the mv refinement unit 111C of the encoding apparatus has exactly the same configuration as the mv refinement unit 241B of the decoding apparatus, in this embodiment, the mv refinement unit 241B will be described as a representative.

FIG. 9 is a diagram showing an example of functional blocks of the mv refinement unit 241B according to the present embodiment.

As shown in FIG. 9 , the mv refinement unit 241B includes an MMVD unit 241B1 and a DMVR unit 241B2.

Specifically, the MMVD unit 241B1 and the DMVR unit 241B2 refine the motion vector using MMVD (Merge mode with MVD) and DMVR (Decoder side Motion Vector Refinement) adopted in Non-Patent Document 1.

Specifically, the MMVD unit 241B1 is configured to set the correction range of the reference position by the distance and direction (vertical and horizontal) as shown in FIG. 9 based on the reference position of the motion vector output from the combining unit 111A2.

The MMVD unit 241B1 is configured to perform a refinement process by specifying a correction position with the smallest specific cost from the correction range as a correction distance, and correcting the motion vector based on the correction reference position.

Then, the DMVR unit 241B2 is configured to perform refinement processing by setting a search range with reference to the reference position specified by the motion vector output from the combining unit 111A2, specifying a correction reference position with the smallest specific cost from the search range, and based on Correct the reference position and correct the motion vector.

Here, the mv refinement unit 241B also determines whether or not to apply MMVD to the target block and whether to apply DMVR. In the present invention, the known method described in Non-Patent Document 1 can be used for this determination process, so the description thereof is omitted. .

In addition, when both MMVD and DMVR are invalid, the motion vector output from the combining unit 111A2 is directly output to the prediction signal generating unit 241C in the subsequent stage without correction.

(merge list construction method)

Next, the merge list construction process of the present embodiment will be described with reference to FIG. 10 . FIG. 10 is a flowchart showing an example of the merge list construction process of the present embodiment.

As shown in FIG. 10 , as in Non-Patent Document 1, the merged list construction process of the present invention is composed of five merged list construction processes in total.

Specifically, there are five types of spatial merging in step S10-1, temporal merging in step S10-2, historical merging in step S10-3, pairwise average merging in step S10-4, and zero merging in step S10-5. Merge list construction processing composition. The respective merged list construction processes will be described later.

FIG. 11 is a diagram showing an example of a merged list generated by the merged list construction process according to the present embodiment.

As described above, the merge list refers to a list in which the motion vector, Refidx, and hepelIfIdx corresponding to the merge index are registered.

Here, the maximum number of merge indexes is set to "5" in Non-Patent Document 1, but can be freely set according to the intention of the designer.

In addition, mvL0, mvL1, RefIdxL0, and RefIdxL1 in FIG. 11 represent motion vectors and reference image indices of the reference image lists L0 and L1, respectively.

Here, the reference picture lists L0 and L1 represent lists in which reference frames are registered, and the reference frames are specified based on RefIdx.

In addition, the merge list shown in FIG. 11 shows motion vectors and reference image indices of both L0 and L1, but may be unidirectional prediction depending on the reference block. In this case, the unidirectional motion vector and reference image index are registered in the merge list. Also, when the motion vector does not originally exist in the reference block, the merge list construction process for the reference block is skipped.

(space merge)

FIG. 12 is a diagram illustrating spatial merging. Spatial merging is a technique of inheriting mv, RefIdx, and hpelIfIdx from adjacent blocks existing in the same frame as the target block.

Specifically, the above-mentioned mv, Refidx, and hpelfIdx are used from the adjacent blocks in the positional relationship as shown in FIG. 12 , and the processing order may be as shown in FIG. 12 , as in Non-Patent Document 1. order.

In addition, in the merge list processing, parameters are registered in the merge list in the above-described processing order, but there is a checking mechanism such that the same motion vector and reference image index are not registered in the merge list. This is called pruning (cropping) processing.

The reason for the existence of the pruning process is to increase the changes of the motion vectors registered in the merge list and the reference image index. From the perspective of the image encoding apparatus 100, the motion vector with the smallest specific cost can be selected according to the image characteristics. In the image decoding apparatus 200 , a prediction signal with high prediction accuracy can be generated based on the selected motion vector and the reference image index, and as a result, the effect of improving the encoding performance can be expected.

In the spatial merging, for example, when the adjacent block A ₁ is registered, the adjacent block B ₁ in the next processing order is confirmed to be the same as the motion vector and the reference image index registered for the adjacent block A ₁ . If the identity is confirmed, the motion vector and reference image index _of the adjacent block B1 will not be registered in the merge list.

In addition, in Non-Patent Document 1, for the adjacent block B ₀ , the adjacent block A ₀ , and the adjacent block B ₂ , in addition to checking the identity with the motion vector and the reference image index registered in the merge list, the Check whether the object block is a triangle merge.

In the present embodiment, the determination of the triangle merge may be added to the pruning process, and a known method can be adopted as the triangle merge, so the description thereof will be omitted.

In addition, in Non-Patent Document 1, the maximum number of merging indexes that can be registered for spatial merging is set to "4", and the adjacent block B ₂ has four merging indexes registered by the spatial merging processing so far. , _skip the processing of B2.

In the present embodiment, similarly to Non-Patent Document 1, it is possible to determine the processing of the adjacent block B2 based _on the number of existing merge index registrations.

(time merge)

FIG. 13 is a diagram showing time merging. Temporal merging is a technique of specifying as a reference a lower left adjacent block (C ₁ in FIG. 13 ) or a co-located block (C ₀ in FIG. 13 ) that exists in a different frame from the target block but is co-located block, and inherits the motion vector and reference picture index.

In Non-Patent Document 1, the maximum registrable number of the merging indexes of the time merging list in the merging list is "1", and in the present embodiment, the maximum registrable number may be similarly set.

Also, the motion vector used for temporal integration has the feature of being scaled, and FIG. 14 is a diagram showing the scaling process.

Specifically, as shown in FIG. 14 , based on the distance tb between the reference frame of the target block and the frame where the target frame is located, and the distance td between the reference frame of the reference block and the reference frame of the reference block, the mv of the reference block is scaled as follows .

mv'=(td/tb)×mv

In temporal merging, the scaled mv' is registered in the merging index as a motion vector corresponding to the merging index.

(Historical merge)

FIG. 15 is a diagram showing history merging. History merging is a technique in which the motion vector, reference image index, and half-pixel index of the inter-frame prediction block that has been coded before the target block are separately stored in a storage area called the history merging table. If the space merging process and the time merging process in the previous stage are not full, the merge index registered in the history merge table is registered in the merge list.

FIG. 15 is a diagram showing an example of a history merge table construction process, which is a configuration in which a motion vector corresponding to a previously coded block, a reference picture index, and a half-pixel index are registered in the history merge table based on the history merge index. .

In Non-Patent Document 1, the maximum number of registrations of the history merge index in the history merge table is set to "6" at the maximum, and can be freely set according to the intention of the designer.

In addition, the registration process of the history merge index in the history merge table is a FIFO process, and is configured as follows: every time the history merge table is filled and a new history merge table is added, the last registered history merge index is deleted.

Furthermore, as in Non-Patent Document 1, when the target block spans a Coding Tree Block (CTU, Coding TreeBlock), the history merge index registered in the history merge table may be initialized.

(Pairwise Average Merged)

FIG. 16 is a diagram showing a combination of a new motion vector and half-pixel index calculated by pairwise average merging.

Pairwise average merging is a technique of generating a new motion vector, reference image index, half-pixel index using motion vectors, reference image indices, half-pixel indices corresponding to the two sets of merge indices already registered in the merge list.

Regarding the two sets of merge indexes used for pairwise average merge, as in Non-Patent Document 1, the 0th and 1st merge indexes registered in the merge list may be used fixedly, or they may be freely used according to the intention of the designer. Set as a combination of the other two groups.

As shown in FIG. 16 , the method for generating a new motion vector in pairwise average merging is to generate an average value of motion vectors corresponding to two sets of merge indices in the merge list.

Specifically, for example, when there are two motion vectors corresponding to the two sets of merge indices (ie, bidirectional prediction), according to the motion vectors mvL0P ₀ /mvL1P ₀ and mvL0P ₁ /mvL1P ₁ in the L0 and L1 directions, The pairwise average combined motion vectors mvL0Avg and mvL1Avg are independently calculated as follows.

mvL0Avg=(mvL0P ₀ +mvL0P ₁ )/2

mvL1Avg=(mvL1P ₀ +mvL1P ₁ )/2

Here, when one of mvL0P ₀ /mvL1P ₀ or mvL0P ₁ /mvL1P ₁ does not exist, the above calculation is performed excluding the motion vector that does not exist.

At this time, in Non-Patent Document 1, it is stipulated that the reference picture indexes RefIdxL0P ₀ and RefIdxL1P ₀ associated with the merge index P ₀ are always used as the reference picture indexes associated with the pairwise average merge index.

Also, as shown in FIGS. 17( a ) and 17 ( b ), the new half-pixel index hpelIfIdxAvg generated by the pairwise average merging is based on the two sets of half-pixel indices corresponding to the two sets of merge indices registered in the merge list. hpelIfIdxP ₀ and hpelIfIdxP ₁ are set.

Specifically, in step S17-1, it is determined whether hpelIfIdxP ₀ and hpelIfIdxP ₁ are the same. When they are the same, the process proceeds to step S17-2, and when they are not the same, the process proceeds to step S17-3.

In step S17-2, hpelIfIdxAvg is set to hpelIfIdxP ₀ .

In step S17-3, hpelIfIdxAvg is set to "0" which is invalid.

Here, when the possible values of hpelIfIdxP ₀ and hpelIfIdxP ₁ are "0" or "1", the processing of step S17-1 and step S17-3 shown in Fig. 17(a) may be replaced with Fig. 17(b) ) of steps S17-4 to S17-6.

(Import of half-pixel index in temporal binning)

Next, the introduction of the half-pixel index in the temporal binning of the present embodiment will be described with reference to FIG. 18 . FIG. 18 is a diagram showing an example of constructing a merge list according to the present embodiment.

In Non-Patent Document 1, when a merging index for temporal merging is registered in the merging list, the half-pixel index corresponding to the merging index is always set to "0". Therefore, for temporal combining, in Non-Patent Document 1, the smoothing filter is not used, but the HEVC filter is always used when the motion vector refers to a fractional pixel precision position.

Therefore, in this embodiment, the half-pixel index of the temporal integration is not always set to "0", but the half-pixel index of the reference block is directly used and registered in the integration list.

Thus, a smoothing filter can also be used for temporal combining. This means that the selection opportunity of the smoothing filter increases for the entire merge list, and therefore, by adaptively switching the filter according to the image characteristics, the prediction accuracy can be improved, and the encoding performance can be improved.

(Introduction of judgment by half-pixel index to the pruning process when building the merged list)

Hereinafter, the introduction of the judgment using the half-pixel index into the pruning process when constructing the merge list according to the present embodiment will be described.

Non-Patent Document 1 describes a checking mechanism called pruning processing, in which merge indexes having the same motion vector and reference image index are not registered in the merge list when the merge list is constructed.

Specifically, this pruning process works when a new merge index is added to the merge list, and the motion vector and reference index associated with the merge index to be newly added and the motion vector associated with the registered merge index are used. When the index is the same as the reference index, the merge index is not added to the merge list.

This is to intentionally increase the change of the motion vector registered in the merge list. From the image coding apparatus 100 side, the increase in the change of the optional motion vector means that the prediction accuracy of the motion vector for suppressing the coding cost is higher. Choice opportunities increase.

Furthermore, from the side of the image decoding device 200 , an MC predicted image can be generated based on a motion vector with high prediction accuracy selected by the image encoding device 100 , and as a result, the effect of improving the encoding performance can be expected.

However, in Non-Patent Document 1, the half-pixel index is not used in the judgment of the pruning process, and the merge index that has the same motion vector and reference image index as the existing merge index but has a different half-pixel index is not used. Registered in the consolidated list.

Therefore, in the present embodiment, the determination of the half-pixel index is added to the pruning process in the merge list construction.

Accordingly, even when the existing merge index has the same motion vector and reference image index as the conventional method, a merge index having a different half-pixel index is registered in the merge list.

This implies that the selection opportunity of the smoothing filter increases for the merge list, and from the perspective of the image encoding apparatus 100, it means that an interpolation filter with a lower encoding cost can be adaptively selected according to the image characteristics.

In addition, from the image decoding device 200 side, the MC predicted image can be generated using the interpolation filter selected by the image encoding device 100 with a low encoding cost, and as a result, the effect of improving the encoding performance can be expected.

[Example of change: Extension of pruning processing]

In the above example, the judgment of adding a half-pixel index is shown in the pruning process, but in Non-Patent Document 1, the pruning process is performed only when a merging list is constructed using spatial merging and historical merging.

In addition, for the above-mentioned five candidates (processing order: A1, B1, B0, A0, B2), when the triangular merge is invalid, only B0 and B1, A0 and A1, B2 and A1 and B1 are performed in the spatial merge. Compare.

Therefore, in spatial merging of B0, A0, B2, temporal merging, and pairwise average merging, there is a possibility that the motion vector, reference image index, and half-pixel index may overlap with the merging candidates of the previous stage that are not compared.

Therefore, in the method of constructing a merge candidate and a merge list that does not use the pruning process of Non-Patent Document 1, if the pruning process is extended and the judgment of the half-pixel index is added, it is possible to avoid the use of the same motion vector and reference image index. Since merging candidates and half-pixel indices are added to the merging list, an improvement in prediction accuracy can be expected, and an effect of further improving coding performance can be expected.

(Introduction of judgment by half-pixel index to the pruning process when constructing the history merge table)

Hereinafter, the introduction of the judgment by the half-pixel index into the pruning process when constructing the history merge table according to the present embodiment will be described.

In Non-Patent Document 1, there is a checking mechanism called pruning processing, and when the history merging table is constructed, the history merging candidates having the same motion vector and reference picture index are not registered in the history merging table.

Specifically, this pruning process is used when a new history merging candidate is added to the history merging table, and the motion vector and reference index associated with the history merging candidate to be newly added are related to the registered history merging candidate. If the associated motion vector and reference index are the same, the history merge candidate is not added to the history merge table.

This is to intentionally increase the change of the motion vector registered in the historical merge table, and from the side of the image coding apparatus 100, the increase of the change of the optional motion vector means that the motion vector with higher prediction accuracy for suppressing the coding cost increased choice.

Furthermore, from the side of the image decoding device 200 , an MC predicted image can be generated based on a motion vector with high prediction accuracy selected by the image encoding device 100 , and as a result, the effect of improving the encoding performance can be expected.

However, in Non-Patent Document 1, the half-pixel index is not used in the judgment of the pruning process, and the historical merging candidate has the same motion vector and reference image index as the existing historical merging candidate, but has a different half-pixel index. Not registered in the historical consolidation table.

Therefore, in the present embodiment, the determination of the half-pixel index is added to the pruning process in the construction of the historical merge table.

As a result, compared with the conventional method, even when the existing historical merging candidates have the same motion vector and reference image index, the historical merging candidates with different half-pixel indices are registered in the merging list. .

This implies that the selection opportunity of the smoothing filter is increased for the history merge table, and from the perspective of the image encoding apparatus 100, it means that an interpolation filter with a lower encoding cost can be adaptively selected according to the image characteristics.

In addition, from the image decoding device 200 side, the MC predicted image can be generated using an interpolation filter with a lower encoding cost selected by the image encoding device 100, and as a result, the effect of improving the encoding performance can be expected.

According to the present invention, by adding the judgment of the half-pixel index to the judgment condition of the pruning process when constructing the merge list or the history merge table, the selection opportunity of the smoothing filter is increased, and as a result, the improvement of the coding performance can be expected.

The image encoding device 100 and the image decoding device 200 described above can also be realized by a program for causing a computer to execute each function (each step).

In addition, in each of the above-described embodiments, the present invention has been described as an example in which the present invention is applied to the image encoding device 100 and the image decoding device 200, but the present invention is not limited to this, and the present invention can also be applied to devices having the image encoding device 100 and the image decoding device 200 as an example. An image encoding system and an image decoding system of each function of the decoding device 200 .

[Symbol Description]

10: image processing system; 100: image coding device; 111, 241: inter prediction unit; 111A: mv derivation unit; 111A1, 241A1: AMVP unit; 111A2, 241A2: combining unit; 111B: AMVR unit; mv refinement unit; 111D, 241C: prediction signal generation unit; 111D1, 241C1: filter determination unit; 111D2, 241C2: filter application unit; 112, 242: intra prediction unit; 121: subtractor; 122, 230: adder; 131: transform and quantization unit; 132, 220: inverse transform and inverse quantization unit; 140: coding unit; 150, 250: loop filter processing unit; 160, 260: frame buffer; 200: image decoding device; 210: decoding unit; 241A: mv decoding unit; 241B1: MMVD unit; 241B2: DMVR unit.

Claims (5)

1. An image decoding apparatus, comprising:

a merging unit configured to decode a motion vector and a half-pixel index indicating whether or not the motion vector refers to an 1/2-pixel-precision position, based on a merge index;

a Motion Vector Refinement unit configured to refine the Motion Vector by mmvd (large Motion Vector difference) or DMVR (Decoder-side Motion Vector reference);

a filter determination unit configured to determine whether to use an interpolation filter and an interpolation filter type based on the refined motion vector and the half-pixel index; and

a filter application unit configured to generate a motion-compensated prediction pixel signal using the interpolation filter; and the number of the first and second electrodes,

the merging unit is configured to generate a merge list by a specific merge list construction method, decode the motion vector and the half-pixel index based on the merge list and the merge index,

the object blocks are merged together and,

the merging unit is configured to register the motion vector and the reference picture index corresponding to the different merge indices in the merge list as different merge indices when the half-pixel indices corresponding to the merge indices are different even if the motion vector and the reference picture index corresponding to the different merge indices are the same when the merge list is constructed.

2. An image decoding apparatus, comprising:

a merging unit configured to decode a motion vector and a half-pixel index indicating whether or not the motion vector refers to an 1/2-pixel-precision position, based on a merge index;

a Motion Vector Refinement unit configured to refine the Motion Vector by mmvd (large Motion Vector difference) or DMVR (Decoder-side Motion Vector reference);

a filter determination unit configured to determine whether to use an interpolation filter and an interpolation filter type based on the refined motion vector and the half-pixel index; and

a filter application unit configured to generate a motion-compensated prediction pixel signal using the interpolation filter; and the number of the first and second electrodes,

the merging unit is configured to generate a merge list by a specific merge list construction method, decode the motion vector and the half-pixel index based on the merge list and the merge index,

the object blocks are merged together and,

the merging unit is configured to register a different history merge candidate in the history merge table when a half-pixel index corresponding to the history merge candidate is different even if a motion vector and a reference image index corresponding to the different history merge candidate are the same when the history merge table is constructed.

3. An image decoding apparatus, comprising:

a merging unit configured to decode a motion vector and a half-pixel index indicating whether or not the motion vector refers to an 1/2-pixel-precision position, based on a merge index;

a Motion Vector Refinement unit configured to refine the Motion Vector by mmvd (large Motion Vector difference) or DMVR (Decoder-side Motion Vector reference);

a filter determination unit configured to determine whether to use an interpolation filter and an interpolation filter type based on the refined motion vector and the half-pixel index; and

a filter application unit configured to generate a motion-compensated prediction pixel signal using the interpolation filter; and the number of the first and second electrodes,

the merging unit is configured to generate a merge list by a specific merge list construction method, decode the motion vector and the half-pixel index based on the merge list and the merge index,

the object blocks are merged together and,

the merging unit is configured to continue using the half-pixel index of the reference block and register the half-pixel index in the merge list when registering a temporally merged merge index in the merge list.

4. An image decoding method, comprising: step A, decoding a motion vector and a half-pixel index according to a merged index, wherein the half-pixel index represents whether the motion vector refers to 1/2 pixel precision positions;

b, thinning the Motion Vector through MMVD (Large Motion Vector difference) or DMVR (Decoder-side Motion Vector reference);

step C, based on the refined motion vector and the half-pixel index, judging whether to use an interpolation filter and an interpolation filter type; and

a step D of generating a motion-compensated prediction pixel signal using the interpolation filter; and the number of the first and second electrodes,

in the step a, a merge list is generated by a specific merge list construction method, and the motion vector and the half-pel index are decoded according to the merge list and the merge index,

the object blocks are merged together and,

the merging unit is configured to, when the half-pixel index corresponding to the merge index is different from the reference image index, register the motion vector and the reference image index as a different merge index in the merge list, even if the motion vector and the reference image index corresponding to the different merge index are the same.

5. A program for causing a computer to function as an image decoding device,

the image decoding apparatus includes:

a merging unit configured to decode a motion vector and a half-pixel index indicating whether or not the motion vector refers to an 1/2-pixel-precision position, based on a merge index;

a Motion Vector Refinement unit configured to refine the Motion Vector by mmvd (large Motion Vector difference) or DMVR (Decoder-side Motion Vector reference);

a filter determination unit configured to determine whether to use an interpolation filter and an interpolation filter type based on the refined motion vector and the half-pixel index; and

a filter application unit configured to generate a motion-compensated prediction pixel signal using the interpolation filter; and the number of the first and second electrodes,

the merging unit is configured to generate a merge list by a specific merge list construction method, decode the motion vector and the half-pixel index based on the merge list and the merge index,

the object blocks are merged together and,

the merging unit is configured to register the motion vector and the reference picture index corresponding to the different merge indices in the merge list as different merge indices when the half-pixel indices corresponding to the merge indices are different even if the motion vector and the reference picture index corresponding to the different merge indices are the same when the merge list is constructed.

Images