Encoder, a decoder and corresponding methods for intra prediction
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.
1. An encoding device, comprising:
one or more processors; and
a non-transitory computer-readable storage medium coupled to the one or more processors and storing programming for execution by the one or more processors, wherein the programming, when executed by the one or more processors, configures the encoding device to:
when an intra prediction mode IntraPredModeY of a current block is not included in a set of most probable modes, derive the intra prediction mode IntraPredModeY of the current block by:
for each candidate intra prediction mode candModeList[i] in an array of candidate intra prediction modes, when the intra prediction mode IntraPredModeY is greater than candModeList[i], reduce a value of the intra prediction mode IntraPredModeY 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 numbers, N>M; and
reduce the value of the intra prediction mode IntraPredModeY by one;
wherein the intra prediction mode IntraPredModeY specifies a luma intra prediction mode at a luma location that a top-left sample of the current block relative to a top-left luma sample of a current picture.
2. The encoding device of claim 1 , wherein candModeList[i] in the array 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.
3. The encoding device of claim 2 , wherein the programming, when executed by the one or more processors, further configures the encoding device to:
derive the candidate intra prediction mode candModeList[i] by: when candModeList[i] is greater than candModeList[i+1], swapping values of candModeList[i] and candModeList[i+1], wherein i ranges from M to N−1.
4. The encoding device of claim 1 , wherein the programming, when executed by the one or more processors, further configures the encoding device to:
send a bitstream to a decoder, wherein the bitstream comprises a value of an indication information of the current block, the value of the indication information indicating whether the intra prediction mode of the current block is in the set of most probable modes.
5. The encoding device of claim 4 , wherein the value of the indication information is indicated by a flag intra_luma_mpm_flag, and when a value of the flag intra_luma_mpm_flag is not equal to 1, the intra prediction mode of the current block is not in the set of most probable modes.
6. The encoding device of claim 5 , wherein a syntax element intra_luma_mpm_remainder represents truncated binary code of a mode that is not in the set of most probable modes.
7. The encoding device of claim 1 , wherein the set of most probable modes comprises five candidate intra prediction modes and a planar mode.
8. The encoding device of claim 7 , wherein a planar flag indicates whether the intra prediction mode IntraPredModeY of the current block is the planar mode or not.
9. The encoding device of claim 8 , wherein the planar flag is context adaptive binary arithmetic coding (CABAC) coded.
10. The encoding device of claim 9 , wherein the context 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.
11. The encoding device of claim 1 , wherein N is 4, M is 0.
12. A non-transitory computer-readable medium storing a bitstream that is generated by a video encoding method performed by a video encoding apparatus, the bitstream comprises:
an indication information of a current block, a value of the indication information indicating whether an intra prediction mode IntraPredModeY of the current block is included in a set of most probable modes; and
a syntax element intra_luma_mpm_remainder 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 IntraPredModeY 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 IntraPredModeY is greater than candModeList[i], reducing a value of the intra prediction mode IntraPredModeY 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 a value of the intra prediction mode IntraPredModeY by one;
wherein the intra prediction mode IntraPredModeY specifies a luma intra prediction mode at a luma location that a top-left sample of the current block relative to a top-left luma sample of a current picture.
13. The non-transitory computer-readable medium of claim 12 , wherein candModeList[i] in the array 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.
14. The non-transitory computer-readable medium of claim 13 , 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], wherein i ranges from M to N−1.
15. The non-transitory computer-readable medium of claim 12 , wherein the value of the indication information is indicated by a flag intra_luma_mpm_flag, and wherein when a value of the flag intra_luma_mpm_flag is not equal to 1, the intra prediction mode of the current block is not in the set of most probable modes.
16. The non-transitory computer-readable medium of claim 12 , wherein the set of most probable modes comprises five candidate intra prediction modes and a planar mode.
17. The non-transitory computer-readable medium of claim 16 , wherein the bitstream further comprises a planar flag indicating whether the intra prediction mode IntraPredModeY of the current block is the planar mode or not.
18. The non-transitory computer-readable medium of claim 17 , wherein the planar flag is context adaptive binary arithmetic coding (CABAC) coded.
19. The non-transitory computer-readable medium of claim 18 , wherein the context 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.
20. The non-transitory computer-readable medium of claim 12 , wherein N is 4, M is 0.