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1. WO2020141123 - HISTORY-BASED INTRA MOST PROBABLE MODE DERIVATION

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

CLAIMS

1. A method performed by a decoder, the method comprising:

receiving (1810) an encoded video block that includes a sequence of pictures, each of the pictures including a luma value and a chroma value;

generating (1820) a most probable mode, MPM, set that includes a plurality of intra prediction modes that correspond to a history-based analysis; and

performing (1830) an intra prediction for samples to decode the pictures by selecting an intra prediction mode that includes a plurality of directional modes and a plurality of non-directional modes,

wherein generating the MPM set comprises generating at least one mode in the MPM set from an intra mode buffer table that is configured to include intra prediction modes, and wherein the intra mode buffer table comprises a first-in-first-out, FIFO, buffer that includes elements that correspond to a previously decoded video block.

2. The method of Claim 1, wherein the elements are initially predefined elements and wherein a new element replaces at one of the initially predefined elements.

3. The method of any of Claims 1-2, wherein the FIFO buffer comprises a fixed number of elements.

4. The method of any of Claims 1-3, further comprising comparing a new element to existing elements in the FIFO buffer,

wherein responsive to the new element being the same as one of the existing elements in the FIFO buffer, removing the one of the existing elements in the FIFO buffer and adding the new element to a last position of the FIFO buffer, and

wherein responsive to the new element being different from the existing elements in the FIFO buffer, removing the one of the existing elements that is in a first position of the FIFO buffer and adding the new element to a last position of the FIFO buffer.

5. The method of any of Claims 1-4, further comprising:

receiving (1940) a new encoded video slice; and

responsive to receiving the new encoded video slice, resetting (1950) the intra mode buffer table to the initially predefined elements.

6. The method of any of Claims 1-5, further comprising:

receiving (2040) a new tile of encoded video slices; and

responsive to receiving the new tile of encoded video slices, resetting (2050) the intra mode buffer table.

7. The method of any of Claims 1-6, further comprising:

receiving (2140) a new group of tiles of encoded video slices; and

responsive to receiving the new group of tiles of encoded video slices, resetting (2150) the intra mode buffer table.

8. The method of any of Claims 1-7, wherein the intra mode buffer table captures intra prediction from previously coded video blocks.

9. The method of any of Claims 1-8, wherein the intra mode buffer table resets responsive to an arithmetic code resetting at least one internal state.

10. The method of any of Claims 7-9, wherein the table is reset to a predefined intra angular mode set.

11. The method of any of Claims 1-10, wherein the intra mode buffer table is maintained during an encoding and/or a decoding operation.

12. The method of any of Claims 1-11, wherein the intra mode buffer table comprises elements corresponding to a plurality of unique angular intra prediction modes,

wherein responsive to receiving a new element comprising one of the plurality of angular intra prediction modes, adding the new element to a last entry of the intra mode buffer table and removing a matching one of the plurality of angular predictions modes from the intra mode buffer table, and

wherein responsive to receiving a new element comprising a different angular prediction mode than the plurality of angular intra prediction modes, adding the new element to a last entry of the intra mode buffer table and removing a first entry of the intra mode buffer table.

13. The method of any of Claims 1-12, wherein generating the MPM set comprises:

responsive to a left neighboring block being decoded by an intra prediction mode L and a multi-reference line index being zero, adding the intra prediction mode L to the MPM set; and responsive to the left neighboring block being decoded by the intra prediction mode L, the multi-reference line index being greater than zero and the intra prediction mode L being greater than a DC index, adding the intra prediction mode L to the MPM set.

14. The method of any of Claims 1-12, wherein generating the MPM set comprises:

responsive to an above neighboring block being decoded by an intra prediction mode A, a multi-reference line index being zero and intra prediction mode A not being in the MPM set, adding the intra prediction mode A to the MPM set; and

responsive to the above neighboring block being decoded by the intra prediction mode A, the multi-reference line index being greater than zero and the intra prediction mode A being greater than a DC index, and the intra prediction mode A not being in the MPM set, adding the intra prediction mode A to the MPM set.

15. The method of any of Claims 1-12, wherein generating the MPM set comprises:

responsive to a multi-reference line index being zero and a planar mode not being in the MPM set, adding the planar mode to the MPM set; and

responsive to the multi-reference line index being zero and a DC mode not being in the MPM set, adding the DC mode to the MPM set.

16. The method of any one of Claims 1-12, wherein generating the MPM set comprises: responsive to intra prediction mode X not being in the MPM set, adding the intra prediction mode X to the MPM set at a last position of the intra mode buffer table; and

responsive to the intra prediction mode X being in the MPM set and adjacent intra prediction mode X-l not being in the MPM set, adding the adjacent intra prediction mode X-l to the MPM set at a last position of the intra mode buffer table.

17. The method of any one of Claims 1-12, wherein generating the MPM set comprises: responsive to the intra prediction mode X being in the MPM set and the MPM set being incomplete and adjacent intra prediction mode X+l not being in the MPM set, adding the adjacent intra prediction mode X+l to the MPM set at a last position of the intra mode buffer table.

18. The method of any of Claims 1-17, wherein the MPM set comprises six modes.

19. The method of any of Claims 1-17, wherein the MPM set comprises a plurality of MPM modes, and wherein the intra mode buffer table further generates a portion of the plurality of modes in a non-MPM set.

20. The method of any of Claims 1-17, wherein the MPM set comprises nine modes, and wherein first six modes in MPM set comprises MPM modes and last three modes comprises a portion of modes in non-MPM set.

21. The method of Claim 20, wherein the non-MPM set is derived by sorting prediction modes from a smallest to a largest mode index.

22. The method of any of Claims 1-21, further comprising resetting the intra mode buffer table to a pre-defined intra modes ordering responsive to starting a new coding tree unit.

23. The method of any of Claims 1-22, wherein the intra mode buffer table comprises a plurality of intra mode buffer tables, and wherein each of the plurality of intra mode buffer tables comprises a different block dimensional characteristic from other ones of the plurality of intra mode buffer tables.

24. The method of any of Claims 1-23, wherein responsive to the block being decoded using an intra prediction mode that is an angular intra prediction mode, adding the angular intra prediction mode to a last entry of the intra mode buffer table.

25. The method of any of Claims 1-24, determining a block size relative to a block size threshold, responsive to the block size being less than the block size threshold, not updating the intra mode buffer table corresponding to the block.

26. The method of any of Claims 1-25, determining a block dimension ratio of a first block dimension to a second block dimension, comparing the block dimension ratio to a block dimension ratio threshold, responsive to the block dimension ratio being less than the block dimension ratio threshold, not updating the intra mode buffer table corresponding to the block.

27. The method of any of Claims 1-26, determining a minimum block dimension relative to a block dimension threshold, responsive to the minimum block dimension being less than the block dimension threshold, not updating the intra mode buffer table corresponding to the block.

28. The method of any of Claims 1-27, wherein performing the intra prediction for samples to decode the pictures comprises selecting the intra prediction mode from the MPM set.

29. A method performed by an encoder, the method comprising:

receiving (2210) an encoded video block that includes a sequence of pictures, each of the pictures including a luma value and a chroma value;

generating (2220) a most probable mode, MPM, set that includes a plurality of intra prediction modes that correspond to a history-based analysis; and

performing (2230) an intra prediction for samples to encode the pictures by selecting an intra prediction mode that includes a plurality of directional modes and a plurality of non-directional modes,

wherein generating the MPM set comprises generating at least one mode in the MPM set from an intra mode buffer table that is configured to include intra prediction modes, and wherein the intra mode buffer table comprises a first-in-first-out, FIFO, buffer that includes elements that correspond to a previously decoded video block.

30. The method of Claim 29, wherein the elements are initially predefined elements and wherein a new element replaces at one of the initially predefined elements.

31. The method of any of Claims 29-30, wherein the FIFO buffer comprises a fixed number of elements.

32. The method of any of Claims 29-31, further comprising comparing a new element to existing elements in the FIFO buffer,

wherein responsive to the new element being the same as one of the existing elements in the FIFO buffer, removing the one of the existing elements in the FIFO buffer and adding the new element to a last position of the FIFO buffer, and

wherein responsive to the new element being different from the existing elements in the FIFO buffer, removing the one of the existing elements that is in a first position of the FIFO buffer and adding the new element to a last position of the FIFO buffer.

33. The method of any of Claims 29-32, further comprising:

receiving (1940) a new encoded video slice; and

responsive to receiving the new encoded video slice, resetting (1950) the intra mode buffer table to the initially predefined elements.

34. The method of any of Claims 29-33, further comprising:

receiving (2040) a new tile of encoded video slices; and

responsive to receiving the new tile of encoded video slices, resetting (2050) the intra mode buffer table.

35. The method of any of Claims 29-34, further comprising:

receiving (2140) a new group of tiles of encoded video slices; and

responsive to receiving the new group of tiles of encoded video slices, resetting (2150) the intra mode buffer table.

36. The method of any of Claims 29-35, wherein the intra mode buffer table captures intra prediction from previously coded video blocks.

37. The method of any of Claims 29-36, wherein the intra mode buffer table resets responsive to an arithmetic code resetting at least one internal state.

38. The method of any of Claims 36-37, wherein the table is reset to a predefined intra angular mode.

39. The method of any of Claims 29-38, wherein the intra mode buffer table is maintained during an encoding and/or a decoding operation.

40. A method of any of Claims 29-39, wherein the intra mode buffer table comprises elements corresponding to a plurality of unique angular intra prediction modes,

wherein responsive to receiving a new element comprising one of the plurality of angular intra prediction modes, adding the new element to a last entry of the intra mode buffer table and removing a matching one of the plurality of angular predictions modes from the intra mode buffer table, and

wherein responsive to receiving a new element comprising a different angular prediction mode than the plurality of angular intra prediction modes, adding the new element to a last entry of the intra mode buffer table and removing a first entry of the intra mode buffer table.

41. A method of any of Claims 29-40, wherein generating the MPM set comprises:

responsive to a left neighboring block being encoded by an intra prediction mode L and a multi-reference line index being zero, adding the intra prediction mode L to the MPM set; and responsive to the left neighboring block being encoded by the intra prediction mode L, the multi-reference line index being greater than zero and the intra prediction mode L being greater than a DC index, adding the intra prediction mode L to the MPM set.

42. A method of any of Claims 29-40, wherein generating the MPM set comprises:

responsive to an above neighboring block being encoded by an intra prediction mode A, a multi-reference line index being zero and intra prediction mode A not being in the MPM set, adding the intra prediction mode A to the MPM set; and

responsive to the above neighboring block being encoded by the intra prediction mode A, the multi-reference line index being greater than zero and the intra prediction mode A being greater than a DC index, and the intra prediction mode A not being in the MPM set, adding the intra prediction mode A to the MPM set.

43. A method of any of Claims 29-40, wherein generating the MPM set comprises:

responsive to a multi-reference line index being zero and a planar mode not being in the

MPM set, adding the planar mode to the MPM set; and

responsive to the multi-reference line index being zero and a DC mode not being in the MPM set, adding the DC mode to the MPM set.

44. A method of any one of Claims 29-40, wherein generating the MPM set comprises: responsive to intra prediction mode X not being in the MPM set, adding the intra prediction mode X to the MPM set at a last position of the intra mode buffer table; and

responsive to the intra prediction mode X being in the MPM set and adjacent intra prediction mode X-l not being in the MPM set, adding the adjacent intra prediction mode X-l to the MPM set at a last position of the intra mode buffer table.

45. A method of any one of Claims 29-40, wherein generating the MPM set comprises: responsive to the intra prediction mode X being in the MPM set and the MPM set being incomplete and adjacent intra prediction mode X+l not being in the MPM set, adding the adjacent intra prediction mode X+l to the MPM set at a last position of the intra mode buffer table.

46. The method of any of Claims 29-45, wherein the MPM set comprises six modes.

47. The method of any of Claims 29-45, wherein the MPM set comprises a plurality of MPM modes, and wherein the intra mode buffer table further generates a portion of the plurality of modes in a non-MPM set.

48. The method of any of Claims 29-45, wherein the MPM set comprises nine modes, and wherein the first six modes in MPM set comprises MPM modes and the last three modes in MPM set comprises a portion of modes in non-MPM set.

49. The method of Claim 48, wherein the non-MPM set is derived by sorting prediction modes from a smallest to a largest mode index.

50. The method of any of Claims 29-49, further comprising resetting the intra mode buffer table to a pre-defined intra modes ordering responsive to a using a new coding tree unit.

51. The method of any of Claims 29-50, wherein the intra mode buffer table comprises a plurality of intra mode buffer tables, and wherein each of the plurality of intra mode buffer tables comprises a different block dimensional characteristic from other ones of the plurality of intra mode buffer tables.

52. The method of any of Claims 29-51, wherein responsive to the block being encoded using an intra prediction mode that is an angular intra prediction mode, adding the angular intra prediction mode to a last entry of the intra mode buffer table.

53. The method of any of Claims 29-52, determining a block size relative to a block size threshold, responsive to the block size being less than the block size threshold, not updating the intra mode buffer table corresponding to the block.

54. The method of any of Claims 29-53, determining a block dimension ratio of a first block dimension to a second block dimension, comparing the block dimension ratio to a block dimension ratio threshold, responsive to the block dimension ratio being less than the block dimension ratio threshold, not updating the intra mode buffer table corresponding to the block.

55. The method of any of Claims 29-54, determining a minimum block dimension relative to a block dimension threshold, responsive to the minimum block dimension being less than the block dimension threshold, not updating the intra mode buffer table corresponding to the block.

56. The method of any of Claims 29-55, wherein performing the intra prediction for samples to decode the pictures comprises selecting the intra prediction mode from the MPM set.

57. A decoder for a communication network, the decoder comprising:

a processor; and

memory coupled with the processor, wherein the memory comprises instructions that when executed by the processor cause the processor to perform operations, the operations comprising:

receiving (1810) an encoded video block that includes a sequence of pictures, each of the pictures including a luma value and a chroma value;

generating (1820) a most probable mode, MPM, set that includes a plurality of intra prediction modes that correspond to a history-based analysis; and

performing (1830) an intra prediction for samples to decode the pictures by selecting an intra prediction mode that includes a plurality of directional modes and a plurality of non-directional modes,

wherein generating the MPM set comprises generating at least one mode in the MPM set from an intra mode buffer table that is configured to include intra prediction modes, and

wherein the intra mode buffer table comprises a first-in-first-out, FIFO, buffer that includes elements that correspond to a previously decoded video block.

58. The decoder of Claim 57, wherein the instructions are further executable by the processor to cause the processor to perform operations of any of Claims 2-28.

59. An encoder for a communication network, the decoder comprising:

a processor; and

memory coupled with the processor, wherein the memory comprises instructions that when executed by the processor cause the processor to perform operations, the operations comprising:

receiving (2210) an encoded video block that includes a sequence of pictures, each of the pictures including a luma value and a chroma value;

generating (2220) a most probable mode, MPM, set that includes a plurality of intra prediction modes that correspond to a history-based analysis; and

performing (2230) an intra prediction for samples to encode the pictures by selecting an intra prediction mode that includes a plurality of directional modes and a plurality of non-directional modes,

wherein generating the MPM set comprises generating at least one mode in the MPM set from an intra mode buffer table that is configured to include intra prediction modes, and

wherein the intra mode buffer table comprises a first-in-first-out, FIFO, buffer that includes elements that correspond to a previously decoded video block.

60. The encoder of Claim 59, wherein the instructions are further executable by the processor to cause the processor to perform operations of any of Claims 30-56.

61. A computer program comprising computer-executable instructions configured to cause a decoder to perform operations when the computer-executable instructions are executed on a processor comprised in the decoder, the operations comprising:

receiving (1810) an encoded video block that includes a sequence of pictures, each of the pictures including a luma value and a chroma value;

generating (1820) a most probable mode, MPM, set that includes a plurality of intra prediction modes that correspond to a history-based analysis; and

performing (1830) an intra prediction for samples to decode the pictures by selecting an intra prediction mode that includes a plurality of directional modes and a plurality of non-directional modes,

wherein generating the MPM set comprises generating at least one mode in the MPM set from an intra mode buffer table that is configured to include intra prediction modes, and wherein the intra mode buffer table comprises a first-in-first-out, FIFO, buffer that includes elements that correspond to a previously decoded video block.

62. The computer program of Claim 61, wherein the computer-executable instructions are configured to cause the decoder to perform operations of any of Claims 2-28.

63. A computer program comprising computer-executable instructions configured to cause an encoder to perform operations when the computer-executable instructions are executed on a processor comprised in the encoder, the operations comprising:

receiving (2210) an encoded video block that includes a sequence of pictures, each of the pictures including a luma value and a chroma value;

generating (2220) a most probable mode, MPM, set that includes a plurality of intra prediction modes that correspond to a history-based analysis; and

performing (2230) an intra prediction for samples to encode the pictures by selecting an intra prediction mode that includes a plurality of directional modes and a plurality of non-directional modes,

wherein generating the MPM set comprises generating at least one mode in the MPM set from an intra mode buffer table that is configured to include intra prediction modes, and wherein the intra mode buffer table comprises a first-in-first-out, FIFO, buffer that includes elements that correspond to a previously decoded video block.

64. The computer program of Claim 63, wherein the computer-executable instructions are configured to cause the encoder to perform operations of any of Claims 30-56.

65. A computer program product comprising a computer-readable storage medium, the computer-readable storage medium having computer-executable instructions configured to

cause a decoder to perform operations when the computer-executable instructions are executed on a processor comprised in the decoder, the operations comprising:

receiving (1810) an encoded video block that includes a sequence of pictures, each of the pictures including a luma value and a chroma value;

generating (1820) a most probable mode, MPM, set that includes a plurality of intra prediction modes that correspond to a history-based analysis; and

performing (1830) an intra prediction for samples to decode the pictures by selecting an intra prediction mode that includes a plurality of directional modes and a plurality of non-directional modes,

wherein generating the MPM set comprises generating at least one mode in the MPM set from an intra mode buffer table that is configured to include intra prediction modes, and wherein the intra mode buffer table comprises a first-in-first-out, FIFO, buffer that includes elements that correspond to a previously decoded video block.

66. The computer program product of Claim 65, wherein the computer-executable instructions are configured to cause the decoder to perform operations of any of Claims 2-28.

67. A computer program product comprising a computer-readable storage medium, the computer-readable storage medium having computer-executable instructions configured to cause an encoder to perform operations when the computer-executable instructions are executed on a processor comprised in the encoder, the operations comprising:

receiving (2210) an encoded video block that includes a sequence of pictures, each of the pictures including a luma value and a chroma value;

generating (2220) a most probable mode, MPM, set that includes a plurality of intra prediction modes that correspond to a history-based analysis; and

performing (2230) an intra prediction for samples to encode the pictures by selecting an intra prediction mode that includes a plurality of directional modes and a plurality of non-directional modes,

wherein generating the MPM set comprises generating at least one mode in the MPM set from an intra mode buffer table that is configured to include intra prediction modes, and wherein the intra mode buffer table comprises a first-in-first-out, FIFO, buffer that includes elements that correspond to a previously decoded video block.

68. The computer program of Claim 67, wherein the computer-executable instructions are configured to cause the encoder to perform operations of any of Claims 30-56.