Encoder, a decoder and corresponding methods for intra prediction

Patent metadata

Field	Value
Publication number	US-12149684-B2
Application number	US-202217856428-A
Country	US
Kind code	B2
Filing date	Jul 1, 2022
Priority date	Mar 23, 2019
Publication date	Nov 19, 2024
Grant date	Nov 19, 2024

Abstract

Devices and methods for Intra prediction are provided. The method includes: obtaining a value of an indication information of a current block. When the value of the indication information indicates the intra prediction mode of the current block is not comprised in the set of most probable modes, deriving the intra prediction mode IntraPredModeY of the current block by the following ordered steps: i. IntraPredModeY is set equal to intra_luma_mpm_remainder[xCb][yCb], ii. The value of IntraPredModeY is incremented by one. The method can improve the efficiency to determine the intra prediction mode of the current block.

First claim

The invention claimed is:

1. A device, comprising:
a receiver, configured to receive a bitstream; and
at least one storage medium configured to store the bitstream;
wherein the bitstream comprises:
indication information of a current block, a value of the indication information indicating whether an intra prediction mode of the current block is included in a set of most probable modes; and
a syntax element representing a remainder intra prediction mode when the value of the indication information indicates the intra prediction mode of the current block is not included in the set of most probable modes;
wherein the intra prediction mode of the current block is derived by:
setting the intra prediction mode equal to the syntax element, and incrementing a value of the intra prediction mode by one; and
for each candidate intra prediction mode candModeList[i] in an array of candidate intra prediction modes, when the intra prediction mode is greater than candModeList[i], incrementing a value of the intra prediction mode by one, wherein candModeList[i] represents a candidate intra prediction mode in the set of most probable modes, and wherein i ranges from N to M, inclusive, N and M are natural number, N>M.

2. The device of claim 1 , wherein
a candidate intra prediction mode candModeList[i] in the set of most probable modes is derived by sorting a plurality of candidate intra prediction modes,
for each candModeList[i], candModeList[i]<candModeList[i+1], wherein i ranges from 0 to 3.

3. The device of claim 2 , wherein the candidate intra prediction mode candModeList[i] is derived by:
when candModeList[i] is greater than candModeList[i+1], swapping values of candModeList[i] and candModeList[i+1].

4. The device of claim 1 , wherein the value of the indication information is indicated by a flag, and wherein when the value of the flag is not equal to 1, the intra prediction mode of the current block is not in the set of most probable modes.

5. The device of claim 1 , wherein the syntax element representing the remainder intra prediction mode is truncated binary coded.

6. The device of claim 1 , wherein the set of most probable modes comprises five candidate intra prediction modes and a planar mode.

7. The device of claim 6 , wherein the bitstream further comprises a planar flag indicating whether the intra prediction mode of the current block is the planar mode.

8. The device of claim 7 , wherein the planar flag is context adaptive binary arithmetic coding (CABAC) coded.

9. The device of claim 1 , wherein the intra prediction mode of the current block is further derived by:
for i equal to 0 to 4, inclusive, when the intra prediction mode is greater than or equal to a candidate intra prediction mode candModeList[i], incrementing the value of the intra prediction mode by one.

10. A device, comprising:
at least one storage medium configured to store a bitstream; and
a transmitter configured to transmit the bitstream;
wherein the bitstream comprises:
indication information of a current block, a value of the indication information indicating whether an intra prediction mode of the current block is included in a set of most probable modes; and
a syntax element representing a remainder intra prediction mode when the value of the indication information indicates the intra prediction mode of the current block is not included in the set of most probable modes,
wherein the intra prediction mode of the current block is derived by:
for each candidate intra prediction mode candModeList[i] in an array of candidate intra prediction modes, when the intra prediction mode is greater than candModeList[i], reducing a value of the intra prediction mode by one, wherein candModeList[i] represents a candidate intra prediction mode in the set of most probable modes, and wherein i ranges from N to M, inclusive, N and M are natural number, N>M; and
reducing the value of the intra prediction mode by one.

11. The device of claim 10 , wherein
candModeList[i] in the array of candidate intra prediction modes is derived by sorting the candidate intra prediction modes,
for each candModeList[i], candModeList[i]<candModeList[i+1], wherein i ranges from M to N−1.

12. The device of claim 11 , wherein the candidate intra prediction mode candModeList[i] is derived by:
when candModeList[i] is greater than candModeList[i+1], swapping values of candModeList[i] and candModeList[i+1].

13. The device of claim 10 , wherein the value of the indication information is indicated by a flag, and when a value of the flag is not equal to 1, the intra prediction mode of the current block is not in the set of most probable modes.

14. The device of claim 10 , wherein the syntax element is a truncated binary code of a mode that is not in the set of most probable modes.

15. The device of claim 10 , wherein the set of most probable modes comprises five candidate intra prediction modes and a planar mode.

16. The device of claim 15 , wherein the bitstream further comprises a planar flag indicating whether the intra prediction mode of the current block is the planar mode.

17. The device of claim 16 , wherein the planar flag is context adaptive binary arithmetic coding (CABAC) coded.

18. The device of claim 17 , wherein the CABAC indicates whether the current block is an intra block with intra sub-partition (ISP) coding mode enabled, or whether the current block is an intra block with multiple reference line (MRL) enabled.

19. The device of claim 10 , wherein N is 4, M is 0.

Assignees

• Huawei Tech Co Ltd

Inventors

• Wang Biao
• Esenlik Semih
• Kotra Anand Meher
• Gao Han
• Chen Jianle

Classifications

• H04N19/186

  the unit being a colour or a chrominance component · CPC title

• H04N19/159

  Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction · CPC title

• H04N19/13

  Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC] · CPC title

• H04N19/105

  Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction · CPC title

• H04N19/593

  involving spatial prediction techniques · CPC title