US-12627828-B2 - Methods and apparatus of encoding/decoding video picture data

US12627828B2US 12627828 B2US12627828 B2US 12627828B2US-12627828-B2

Abstract

A method for encoding a video picture into a bitstream of encoded video picture data, includes: temporal predicting a video picture block by obtaining a temporal predicted block based on at least one reference block of at least one reference picture pointed to by at least one motion vector associated with the video picture block, wherein if the temporal prediction of the video picture block is based on a single reference block of a reference picture, the method further includes padding the reference block based on a motion vector derived from a nearest subblock of the current block inside the video picture.

Inventors

Fabrice LELÉANNEC
Pierre Andrivon

Assignees

BEIJING XIAOMI MOBILE SOFTWARE CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20230303
Priority Date: 20220407

Claims (14)

1 . A method for encoding a video picture into a bitstream of encoded video picture data, the method comprising: temporal predicting a video picture block by obtaining a temporal predicted block based on at least one reference block of at least one reference picture pointed to by at least one motion vector associated with the video picture block, wherein if the temporal prediction of the video picture block is based on a single reference block of a reference picture, the method further comprises padding the reference block based on a motion vector derived from a nearest subblock of the current block inside the video picture; wherein if the temporal prediction of the video picture block is based on a first reference block of a first reference picture and a second reference block of a second reference picture, the method further comprises obtaining a final motion-compensated prediction of the current video picture block by averaging a first prediction block (P L0 ) and a second prediction block (P L1 ) on a sample basis according to whether a sample ( P ( i , j ) L ⁢ 0 ) at a given position (i,j) of the first prediction block (P L0 ) is outside boundaries of a first reference picture or not, and according to whether a sample ( P ( i , j ) L ⁢ 1 ) at the same position (i,j) of the second prediction block (P L1 ) is outside boundaries of another reference picture or not; wherein the first and second prediction blocks are obtained by using a uni-directional motion-compensated prediction; wherein the reference block of the reference picture is padded based on a motion vector derived from a nearest subblock of the current block inside the video picture and/or the reference block of the other reference picture is padded based on a motion vector derived from a nearest subblock of the current block inside the video picture, and the uni-directional motion-compensated prediction is based on either reference blocks or padded reference blocks.
2 . The method of claim 1 , wherein if the temporal prediction of the video picture block is based on a single reference block of a reference picture and if the reference block is located at least partly outside boundaries of the reference picture, the method further comprises padding the reference block based on a motion vector derived from a nearest subblock of the current block inside the video picture.
3 . The method of claim 1 , wherein the first prediction block (P L0 ) or the second prediction block (P L1 ) is considered as being outside boundaries of the first or second reference picture only when its position in a reference picture is beyond a temporally predicted area extending the reference picture.
4 . The method of claim 1 , wherein the first prediction block (P L0 ) or the second prediction block (P L1 ) is considered as being outside boundaries of the first or second reference picture when it is derived from an inter-coded subblock and as being inside the boundaries of the first or second reference picture when it is derived from an intra-coded subblock.
5 . The method of claim 1 , wherein the nearest subblock is either intra- or inter-coded.
6 . The method of claim 1 , wherein a syntax element is signaled into the bitstream to indicate whether padding the reference blocks of a reference picture is based on a motion vector derived from nearest subblocks of the current blocks inside the video picture or on an intra-prediction-based padding method.
7 . A method for decoding a video picture from a bitstream of encoded video picture data, the method comprising: temporal predicting a video picture block by obtaining a temporal predicted block based on at least one reference block of at least one reference picture pointed to by at least one motion vector associated with the video picture block, wherein if the temporal prediction of the video picture block is based on a single reference block of a reference picture, the method further comprises padding the reference block based on a motion vector derived from a nearest subblock of the current block inside the video picture; wherein if the temporal prediction of the video picture block is based on a first reference block of a first reference picture and a second reference block of a second reference picture, the method further comprises obtaining a final motion-compensated prediction of the current video picture block by averaging a first prediction block (P L0 ) and a second prediction block (P L1 ) on a sample basis according to whether a sample ( P ( i , j ) L ⁢ 0 ) at a given position (i,j) of the first prediction block (P L0 ) is outside boundaries of a first reference picture or not, and according to whether a sample ( P ( i , j ) L ⁢ 1 ) at the same position (i,j) of the second prediction block (P L1 ) is outside boundaries of another reference picture or not; wherein the first and second prediction blocks are obtained by using a uni-directional motion-compensated prediction; wherein the reference block of the reference picture is padded based on a motion vector derived from a nearest subblock of the current block inside the video picture and/or the reference block of the other reference picture is padded based on a motion vector derived from a nearest subblock of the current block inside the video picture, and the uni-directional motion-compensated prediction is based on either reference blocks or padded reference blocks.
8 . The method of claim 7 , wherein if the temporal prediction of the video picture block is based on a single reference block of a reference picture and if the reference block is located at least partly outside boundaries of the reference picture, the method further comprises padding the reference block based on a motion vector derived from a nearest subblock of the current block inside the video picture.
9 . The method of claim 7 , wherein the first prediction block (P L0 ) or the second prediction block (P L1 ) is considered as being outside boundaries of the first or second reference picture only when its position in a reference picture is beyond a temporally predicted area extending the reference picture.
10 . The method of claim 7 , wherein the first prediction block (P L0 ) or the second prediction block (P L1 ) is considered as being outside boundaries of the first or second reference picture when it is derived from an inter-coded subblock and as being inside the boundaries of the first or second reference picture when it is derived from an intra-coded subblock.
11 . The method of claim 7 , wherein the nearest subblock is either intra- or inter-coded.
12 . The method of claim 7 , wherein a syntax element is signaled into the bitstream to indicate whether padding the reference blocks of a reference picture is based on a motion vector derived from nearest subblocks of the current blocks inside the video picture or on an intra-prediction-based padding method.
13 . An apparatus for decoding a video picture from a bitstream of encoded video picture data, comprising: a processor; and a memory storing instructions executable by the processor; wherein the processor is configured to perform the method of claim 7 .
14 . An apparatus for encoding a video picture into a bitstream of encoded video picture data, comprising: a processor; and a memory storing instructions executable by the processor; wherein the processor is configured to perform: temporal predicting a video picture block by obtaining a temporal predicted block based on at least one reference block of at least one reference picture pointed to by at least one motion vector associated with the video picture block, wherein if the temporal prediction of the video picture block is based on a single reference block of a reference picture, the processor is further configured to perform padding the reference block based on a motion vector derived from a nearest subblock of the current block inside the video picture; wherein if the temporal prediction of the video picture block is based on a first reference block of a first reference picture and a second reference block of a second reference picture, the method further comprises obtaining a final motion-compensated prediction of the current video picture block by averaging a first prediction block (P L0 ) and a second prediction block (P L1 ) on a sample basis according to whether a sample ( P ( i , j ) L ⁢ 0 ) at a given position (i,j) of the first prediction block (P L0 ) is outside boundaries of a first reference picture or not, and according to whether a sample ( P ( i , j ) L ⁢ 1 ) at the same position (i,j) of the second prediction block (P L1 ) is outside boundaries of another reference picture or not; wherein the first and second prediction blocks are obtained by using a uni-directional motion-compensated prediction; wherein the reference block of the reference picture is padded based on a motion vector derived from a nearest subblock of the current block inside the video picture and/or the reference block of the other reference picture is padded based on a motion vector derived from a nearest subblock of the current block inside the video picture, and the uni-directional motion-compensated prediction is based on either reference blocks or padded reference blocks.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a US national phase application of International Application No. PCT/CN2023/079676, filed on Mar. 3, 2023, which is based on and claims priority to European Patent Application No. 22305478.4, filed on Apr. 7, 2022, the entire content of both of which is incorporated herein by reference. FIELD The present disclosure generally relates to video picture encoding and decoding. Particularly, but not exclusively, the technical field of the present disclosure is related to motion-compensated temporal prediction with reference blocks overlapping the boundaries of a reference picture. BACKGROUND In the state-of-the-art video compression systems such as HEVC or VVC, low-level and high-level picture partitioning are provided to divide a video picture into picture areas so-called Coding-Tree Units (CTU) which size may be typically between 16×16 and 64×64 pixels for HEVC and 32×32, 64×64, or 128×128 pixels for VVC. SUMMARY According to a first aspect of the present disclosure, there is provided a method of encoding a video picture into a bitstream of encoded video picture data, the method comprising temporal predicting a video picture block by obtaining a temporal predicted block based on at least one reference block of at least one reference picture pointed to by at least one motion vector associated with the video picture block, wherein if the temporal prediction of the video picture block is based on a single reference block of a reference picture, then the method further comprises padding the reference block based on a motion vector derived from a nearest subblock of the current block inside the video picture. According to a second aspect of the present disclosure, there is provided a method for decoding a video picture from a bitstream of encoded video picture data, the method comprising temporal predicting a video picture block by obtaining a temporal predicted block based on at least one reference block of at least one reference picture pointed to by at least one motion vector associated with the video picture block, wherein if the temporal prediction of the video picture block is based on a single reference block of a reference picture, then the method further comprises padding the reference block based on a motion vector derived from a nearest subblock of the current block inside the video picture. According to a third aspect of the present disclosure, there is provided an apparatus comprising means for performing one of the method according to the first and/or second aspect of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Reference will now be made, by way of example, to the accompanying drawings which show exemplary embodiments of the present disclosure, and in which: FIG. 1 shows an example of coding-tree unit in accordance with HEVC; FIG. 2 shows an example of partitioning coding units into prediction units in accordance with HEVC; FIG. 3 shows an example of a CTU division in accordance with VVC; FIG. 4 shows examples of split modes supported in the multi-type tree partitioning in accordance with VVC; FIG. 5 shows a schematic block diagram of steps of a method 100 of encoding a video picture VP in accordance with prior art; FIG. 6 shows a schematic block diagram of steps of a method 200 of decoding a video picture VP in accordance with prior art; FIG. 7 shows an example of a bi-directional motion-compensated prediction in accordance with prior art; FIG. 8 shows a padding method in accordance with prior art; FIG. 9 shows an intra-prediction-based padding method in accordance with prior art; FIGS. 10 and 11 show an example of a first inter-prediction-based padding method in accordance with prior art; FIG. 12 shows an example of a second inter-prediction-based padding method in accordance with prior art; FIG. 13 shows schematically a block diagram of a method 300 of motion compensated prediction in accordance with at least one exemplary embodiment; FIG. 14 shows schematically a block diagram of a method 400 of padding reference blocks of a reference picture in accordance with one exemplary embodiment; and FIG. 15 illustrates a schematic block diagram of an example of a system in which various aspects and exemplary embodiments are implemented. Similar or same elements are referenced with the same reference numbers. DESCRIPTION OF EXEMPLARY EMBODIMENTS At least one of the exemplary embodiments is described more fully hereinafter with reference to the accompanying figures, in which examples of at least one of the exemplary embodiments are depicted. An exemplary embodiment may, however, be embodied in many alternate forms and should not be construed as limited to the examples set forth herein. Accordingly, it should be understood that there is no intent to limit exemplary embodiments to the particular forms disclosed. On the contrary, the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the