US-12621442-B2 - Most probable mode list generation with template-based intra mode derivation and decoder-side intra mode derivation

Abstract

Systems, methods, and instrumentalities are disclosed for most probable mode (MPM) list generation with template-based intra mode derivation (TIMD). An example method involves determining an intra coding mode derivation process is enabled for a first coding block; based on the intra coding mode derivation process being enabled for the first coding block, generating a first MPM list for the first coding block based on a first MPM list generation process; decoding the first coding block based on the first MPM list; determining that the intra coding mode derivation process is disabled for a second coding block; based on the intra coding mode derivation process being disabled for the second coding block, generating a second MPM list for the second coding block based on a second MPM list generation process, different from the first MPM list generation process; and decoding the second coding block based on the second MPM list.

Inventors

• Karam NASER
• Thierry Dumas
• Ya Chen
• Franck Galpin

Assignees

• INTERDIGITAL CE PATENT HOLDINGS, SAS

Dates

Publication Date

20260505

Application Date

20221212

Priority Date

20211221

Claims (20)

1. 1 . A video decoding device comprising: a processor configured to: determine that a template-based intra coding mode derivation process is enabled for a coding block; based on the template-based intra coding mode derivation process being enabled for the coding block, generate a most probable mode (MPM) list for the coding block based on a MPM list generation process, wherein decoder-side intra mode derivation (DIMD) is bypassed in the MPM list generation process; and decode the coding block based on the MPM list.
2. 2 . The video decoding device of claim 1 , wherein the processor being configured to generate the MPM list for the coding block based on the MPM list generation process comprises the processor being configured to: derive a plurality of candidate intra prediction modes, wherein deriving candidate modes via DIMD is bypassed; and add the plurality of candidate intra prediction modes to the MPM list.
3. 3 . The video decoding device of claim 1 , wherein the coding block is a first coding block, the MPM list generation process is a first MPM list generation process, the MPM list is a first MPM list, and the processor is further configured to: determine that the template-based intra coding mode derivation process is disabled for a second coding block; based on the template-based intra coding mode derivation process being disabled for the second coding block, generate a second MPM list for the second coding block based on a second MPM list generation process, wherein DIMD is performed in the second MPM list generation process different from the first MPM list generation process; and decode the second coding block based on the second MPM list.
4. 4 . The video decoding device of claim 3 , wherein the processor being configured to generate the second MPM list for the second coding block based on the second MPM list generation process comprises the processor being configured to: derive a plurality of candidate intra prediction modes based on intra prediction modes associated with neighboring blocks of the second coding block; derive a DIMD candidate for the second coding block based on a histogram of gradients associated with reconstructed pixels neighboring the second coding block; and add the plurality of candidate intra prediction modes and the DIMD candidate to the second MPM list for the second coding block.
5. 5 . The video decoding device of claim 3 , wherein the processor is further configured to: derive a plurality of candidate intra prediction modes for the second coding block based on a histogram of gradients associated with reconstructed pixels neighboring the second coding block, wherein the processor being configured to generate the second MPM list for the second coding block is further based on the derived plurality of candidate intra prediction modes.
6. 6 . The video decoding device of claim 1 , wherein the processor being configured to generate the MPM list for the coding block based on the MPM list generation process comprises the processor being configured to: test a plurality of candidate intra prediction modes on reconstructed pixels neighboring the coding block; select a candidate intra prediction mode from the plurality of candidate intra prediction modes based on the testing; and add the selected candidate intra prediction mode to the MPM list.
7. 7 . The video decoding device of claim 6 , wherein the processor is further configured to: determine whether to add the selected candidate intra prediction mode of the plurality of candidate intra prediction modes to the MPM list by comparing the selected candidate intra prediction mode to prediction modes on the MPM list, wherein on a condition that the selected candidate intra prediction mode is the same as a prediction mode on the MPM list, the processor is configured to refrain from adding the selected candidate intra prediction mode to the MPM list.
8. 8 . The video decoding device of claim 1 , wherein the processor being configured to generate the MPM list for the coding block based on the MPM list generation process comprises the processor being configured to: test a plurality of candidate intra prediction modes on reconstructed pixels neighboring the coding block; select a candidate intra prediction mode from the plurality of candidate intra prediction modes based on the testing; add the selected candidate intra prediction mode to the MPM list; derive a DIMD candidate for the coding block based on a histogram of gradients associated with reconstructed pixels neighboring the coding block; and add the DIMD candidate to the MPM list for the coding block.
9. 9 . The video decoding device of claim 1 , wherein the processor being configured to decode the coding block is further based on the template-based intra coding mode derivation process, the processor is further configured to perform the template-based intra coding mode derivation process, and the processor being configured to perform the template-based intra coding mode derivation process comprises the processor being configured to: test a plurality of candidate intra prediction modes in the MPM list on reconstructed pixels neighboring the coding block; and select a candidate intra prediction mode from the plurality of candidate intra prediction modes based on the testing.
10. 10 . The video decoding device of claim 1 , wherein the processor being configured to generate the MPM list for the coding block further comprises the processor being configured to: derive a plurality of candidate intra prediction modes; and add a derived candidate intra prediction mode of the plurality of candidate intra prediction modes to a primary MPM list of the MPM list; or add the derived candidate intra prediction mode of the plurality of candidate intra prediction modes to a secondary MPM list of the MPM list.
11. 11 . A method for video decoding, the method comprising: determining that a template-based intra coding mode derivation process is enabled for a coding block; based on the template-based intra coding mode derivation process being enabled for the coding block, generating a most probable mode (MPM) list for the coding block based on a MPM list generation process, wherein decoder-side intra mode derivation (DIMD) is bypassed in the MPM list generation process; and decoding the coding block based on the MPM list.
12. 12 . The method of claim 11 , wherein generating the MPM list for the coding block based on the MPM list generation process comprises: deriving a plurality of candidate intra prediction modes, wherein deriving candidate modes via DIMD is bypassed; and adding the plurality of candidate intra prediction modes to the MPM list.
13. 13 . The method of claim 11 , wherein the coding block is a first coding block, the MPM list generation process is a first MPM list generation process, the MPM list is a first MPM list, and the method further comprises: determining that the template-based intra coding mode derivation process is disabled for a second coding block; based on the template-based intra coding mode derivation process being disabled for the second coding block, generating a second MPM list for the second coding block based on a second MPM list generation process, wherein DIMD is performed in the second MPM list generation process different from the first MPM list generation process; and decoding the second coding block based on the second MPM list.
14. 14 . The method of claim 13 , wherein the generating the second MPM list for the second coding block based on the second MPM list generation process comprises: deriving a plurality of candidate intra prediction modes based on intra prediction modes associated with neighboring blocks of the second coding block; deriving a DIMD candidate for the second coding block based on a histogram of gradients associated with reconstructed pixels neighboring the second coding block; and adding the plurality of candidate intra prediction modes and the DIMD candidate to the second MPM list for the second coding block.
15. 15 . The method of claim 13 , wherein the method further comprises: deriving a plurality of candidate intra prediction modes for the second coding block based on a histogram of gradients associated with reconstructed pixels neighboring the second coding block, wherein generating the second MPM list for the second coding block is further based on the derived plurality of candidate intra prediction modes.
16. 16 . The method of claim 11 , wherein generating the MPM list for the coding block based on the MPM list generation process comprises: testing a plurality of candidate intra prediction modes on reconstructed pixels neighboring the coding block; selecting a candidate intra prediction mode from the plurality of candidate intra prediction modes based on the testing; and adding the selected candidate intra prediction mode to the MPM list.
17. 17 . The method of claim 16 , wherein the method further comprises: determining whether to add the selected candidate intra prediction mode of the plurality of candidate intra prediction modes to the MPM list by comparing the selected candidate intra prediction mode to prediction modes on the MPM list, wherein on a condition that the selected candidate intra prediction mode is the same as a prediction mode on the MPM list, the method further comprises refraining from adding the selected candidate intra prediction mode to the MPM list.
18. 18 . The method of claim 11 , wherein generating the MPM list for the coding block based on the MPM list generation process comprises: testing a plurality of candidate intra prediction modes on reconstructed pixels neighboring the coding block; selecting a candidate intra prediction mode from the plurality of candidate intra prediction modes based on the testing; adding the selected candidate intra prediction mode to the MPM list; deriving a DIMD candidate for the coding block based on a histogram of gradients associated with reconstructed pixels neighboring the coding block; and adding the DIMD candidate to the MPM list for the coding block.
19. 19 . The method of claim 11 , wherein decoding the coding block is further based on the template-based intra coding mode derivation process, the method further comprises performing the template-based intra coding mode derivation process, and performing the template-based intra coding mode derivation process comprises: testing a plurality of candidate intra prediction modes in the MPM list on reconstructed pixels neighboring the coding block; and selecting a candidate intra prediction mode from the plurality of candidate intra prediction modes based on the testing.
20. 20 . The method of claim 11 , wherein generating the MPM list for the coding block further comprises: deriving a plurality of candidate intra prediction modes; and adding a derived candidate intra prediction mode of the plurality of candidate intra prediction modes to a primary MPM list of the MPM list; or adding the derived candidate intra prediction mode of the plurality of candidate intra prediction modes to a secondary MPM list of the MPM list.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the National Stage Entry under 35 U.S.C. § 371 of Patent Cooperation Treaty Application No. PCT/EP2022/086853, filed Dec. 20, 2022, which claims the benefit of European Provisional Patent Application No. EP21306876.0, filed Dec. 21, 2021, and European Provisional Patent Application No. EP22305023.8, filed Jan. 12, 2022, the contents of which are incorporated by reference herein. BACKGROUND Video coding systems may be used to compress digital video signals, e.g., to reduce the storage and/or transmission bandwidth needed for such signals. Video coding systems may include, for example, block-based, wavelet-based, and/or object-based systems. SUMMARY Systems, methods, and instrumentalities may be provided for most probable mode (MPM) list generation using different MPM list generation processes for different coding blocks. For example, a device for video decoding may select an MPM generation process for a coding block from multiple MPM list generation processes. The device may base the selection on whether an intra coding mode derivation process is enabled for the coding block. Based on the intra coding mode derivation process being enabled for a coding block, the MPM list for the coding block may be generated based on a first MPM list generation process. Based on the intra coding mode derivation process being disabled for the coding block, the MPM list for the coding block may be generated based on a second and different MPM list generation process. A device for video encoding may select an MPM generation process for a coding block from multiple MPM list generation processes. The device may base the selection on whether an intra coding mode derivation process is enabled for the coding block. Based on the intra coding mode derivation process being enabled for a coding block, the MPM list for the coding block may be generated based on a first MPM list generation process. Based on the intra coding mode derivation process being disabled for the coding block, the MPM list for the coding block may be generated based on a second and different MPM list generation process. In an example, MPM list generation process, candidate intra prediction modes may be generated modes based on intra prediction modes associated with neighboring blocks of the coding block. One or more decoder-side intra mode derivation (DIMD) candidates may be derived for the coding block based on a histogram of gradients associated with reconstructed pixels neighboring the coding block. The candidate intra prediction modes and the DIMD candidate(s) are added to the MPM list for the coding block. In an example MPM list generation process, candidate intra prediction modes may be generated based on intra prediction modes associated with neighboring blocks of the coding block, and deriving candidate modes via DIMD may be bypassed. In an example MPM list generation process, candidate intra prediction modes include TIMD and DIMD derived modes. For example, the MPM list may include intra prediction mode(s) associated with neighboring blocks of the coding block, one intra mode derivation (TIMD) derived mode and/or one DIMD derived mode. For example, intra prediction modes may be tested on reconstructed pixels neighboring the first coding block, and a candidate intra prediction mode may be selected from the candidate intra prediction modes based on the testing. The selected candidate intra prediction mode may be added to the MPM list. A DIMD candidate may be derived based on a histogram of gradients associated with reconstructed samples neighboring the coding block, and the DIMD candidate may be added to the MPM list (e.g., in addition to the selected candidate intra prediction mode). For example, the intra coding mode derivation process based on which the device may select the MPM list generation process may include a template-based process. For example, the intra coding mode derivation process may include TIMD. TIMD may include testing multiple candidate intra prediction modes in the MPM list on reconstructed pixels neighboring the coding block, and selecting a candidate intra prediction mode from the candidate intra prediction modes based on the testing. Based on TIMD being enabled for a coding block, the MPM list may be generated with DIMD bypassed. Based on TIMD being disabled for a coding block, the MPM list may be generated with DIMD. For example, the intra coding mode derivation process, which the device may use to select the MPM list generation process, may be associated with a combined intra-inter prediction (CIIP). Based on CIIP being enabled for a coding block, the MPM list may be generated with DIMD bypassed. Based on TIMD being disabled for a coding block, the MPM list may be generated with DIMD. Systems, methods, and instrumentalities described herein may involve a decoder. In some examples, the systems, methods, and instrumentalities described herein may involve an encoder. In some e