Extensions of intra coding modes in video coding

1. A method for video processing, comprising:

generating, for a conversion between a current video block of a video and a bitstream of the video, a set of extended intra prediction modes (IPMs) associated with the current video block by revising a set of existing IPMs to include at least one new coding method, wherein the new coding method is different from coding methods in the existing IPMs and is to be treated as IPM; and

performing the conversion based on the set of extended IPMs;

wherein the at least one new coding method includes at least one of: a palette mode, an intra block copy (IBC) mode, and a quantized residual block differential pulse-code modulation mode (QR-BDPCM).

2. The method of claim 1 , wherein the set of extended IPMs is signaled with same flag.

3. The method of claim 1 , wherein an index range of the set of existing IPMs is [0, M−1], and an index range of the set of extended IPMs is revised to be [0, M−1+K], wherein K is a number of the at least one new coding method to be included in the set of extended IPMs, wherein M and K are integers.

4. The method of claim 3 , wherein the at least one new coding method is marked as Idx New -th IPM, wherein an IPM index for at least one new coding method Idx New is within the range of [0, M−1+K].

5. The method of claim 4 , wherein the at least one new coding method is included in the set of extended IPMs after all existing IPMs.

6. The method of claim 5 , wherein the IPM index is set by one of the following:

the IPM index for the palette mode is set to M; the IPM index for the IBC mode is set to M or M+1; and the IPM index for the QR-BDPCM mode is set to M, M+1 or M+2.

7. The method of claim 4 , wherein the at least one new coding method is included in the set of extended IPMs before one of existing IPMs.

8. The method of claim 7 , wherein the at least one new coding method is included in the set of extended IPMs before all existing IPMs.

9. The method of claim 8 , wherein an IPM index for one of the at least one new coding method is set to 0.

10. The method of claim 7 , wherein indices of remaining IPMs with original index no smaller than Idx New are revised by being increased by 1.

11. The method of claim 7 , wherein Idx New is pre-defined, or signaled or dependent on at least one of the following:

1) a block dimension of the current video block,

2) a current quantization parameter of the current video block,

3) Indication of a color format including 4:2:0, 4:4:4,

4) Separate/dual coding tree structure,

5) Slice/tile group type and/or picture type,

6) indications signaled in at least one of Sequence Parameter Set (SPS), Picture Parameter Set (PPS), picture header, slice header, tile header.

12. The method of claim 1 , wherein whether and/or how to include a new coding method to the set of existing IPMs depends on block dimension and/or decoded information of the current video block.

13. The method of claim 12 , wherein for M×N blocks, either IBC mode or palette mode is disallowed to be included in the set of extended IPMs, wherein M×N blocks include at least one of 128×128, 128×64 and 64×128 block.

14. The method of claim 12 , wherein for blocks with width larger than K or height larger than L, BDPCM mode is disallowed to be included to the set of extended IPMs, wherein K=32, L=32.

15. The method of claim 1 , wherein whether and/or how to apply the generating or the performing the conversion is based on at least one of the following:

a. video contents including screen contents or natural contents;

b. a message signaled in at least one of DPS, SPS, VPS, PPS, APS, picture header, slice header, tile group header, Largest coding unit (LCU), Coding unit (CU), LCU row, group of LCUs, TU, PU block and Video coding unit;

c. position of at least one of CU, PU, TU, block, Video coding unit;

d. block dimension of the current video block and/or its neighboring blocks;

e. block shape of the current video block and/or its neighboring blocks

f. indication of a color format including 4:2:0, 4:4:4, RGB or YUV;

g. coding tree structure including dual tree or single tree;

h. slice, tile group type and/or picture type;

i. color component including luma component and/or chroma component;

j. temporal layer ID;

k. profiles, levels, tiers of a standard.

16. The method of claim 1 , wherein the conversion includes encoding the current video block into the bitstream.

17. The method of claim 1 , wherein the conversion includes decoding the current video block from the bitstream.

18. An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:

generate, for a conversion between a current video block of a video and a bitstream of the video, a set of extended intra prediction modes (IPMs) associated with the current video block by revising a set of existing IPMs to include at least one new coding method, wherein the new coding method is different from coding methods in the existing IPMs and is to be treated as IPM; and

perform the conversion based on the set of extended IPMs;

wherein the at least one new coding method includes at least one of: a palette mode, an intra block copy (IBC) mode, and a quantized residual block differential pulse-code modulation mode (QR-BDPCM).

19. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:

generating, for a current video block of the video, a set of extended intra prediction modes (IPMs) associated with the current video block by revising a set of existing IPMs to include at least one new coding method, wherein the new coding method is different from coding methods in the existing IPMs and is to be treated as IPM, and

generating the bitstream based on the set of extended IPMs;

wherein the at least one new coding method includes at least one of: a palette mode, an intra block copy (IBC) mode, and a quantized residual block differential pulse-code modulation mode (QR-BDPCM).