Intra-prediction with multiple reference lines

Patent metadata

Field	Value
Publication number	US-11800094-B2
Application number	US-202117518312-A
Country	US
Kind code	B2
Filing date	Nov 3, 2021
Priority date	May 9, 2017
Publication date	Oct 24, 2023
Grant date	Oct 24, 2023

Abstract

A video coding device receives a bitstream including video data. The device determines an intra-prediction mode subset. The intra-prediction mode subset include intra-prediction modes that correlate to a plurality of reference lines for a current image block and excludes intra-prediction modes that correlate to a primary reference line for the current image block. When a first intra-prediction mode is included in the intra-prediction mode subset, the device decodes the first intra-prediction mode by an alternative intra-prediction mode index. When the first intra-prediction mode is not included in the intra-prediction mode subset, the device decodes the first intra-prediction mode by an intra-prediction mode index. The device presents video data including an image block decoded based on the first intra-prediction mode.

First claim

What is claimed is:

1. A video coding method, comprising:
obtaining a reference line index for a coding unit, wherein the coding unit is associated with a plurality of reference lines, and wherein the plurality of reference lines include a primary reference line and one or more additional reference lines that are located further away from the coding unit than the primary reference line;
when the reference line index is set to zero to indicate the primary reference line only, determining a first intra-prediction mode for the coding unit from an intra-prediction mode list; and
when the reference line index is set to a non-zero value to indicate one of the additional reference lines, determining a second intra-prediction mode for the coding unit only from a subset of the intra-prediction mode list, wherein the subset of the intra-prediction mode list includes modes associated with a most probable mode (MPM) list.

2. The video coding method of claim 1 , wherein candidate intra-predication modes in the MPM list include intra-prediction modes used by neighbor coding units of the coding unit.

3. The video coding method of claim 1 , further comprising decoding the coding unit by obtaining a block prediction value based on the first intra-prediction mode or the second intra-prediction mode and the plurality of reference lines.

4. The video coding method of claim 1 , wherein a value of the reference line index is inferred to be equal to zero when not present.

5. The video coding method of claim 1 , wherein the subset of the intra-prediction mode list includes a starting directional intra-prediction mode (DirS), an ending directional intra-prediction mode (DirE), and every Nth directional intra-prediction mode between DirS and DirE, where N is a predetermined integer value.

6. The video coding method of claim 5 , wherein the subset of the intra-prediction mode list further includes planar prediction mode and Direct Current (DC) prediction mode.

7. The video coding method of claim 1 , wherein the subset of the intra-prediction mode list includes a starting directional intra-prediction mode (DirS), an ending directional intra-prediction mode (DirE), a middle directional intra-prediction mode (DirD), a horizontal directional intra-prediction mode (DirH), a vertical directional intra-prediction mode (DirV), and valid directional intra-prediction modes at directions of plus or minus N of DirS, DirE, DirD, DirH, and DirV, where N is a predetermined integer value.

8. The video coding method of claim 7 , wherein the subset of the intra-prediction mode list further includes planar prediction mode and Direct Current (DC) prediction mode.

9. A video coding device comprising a processor configured to:
obtain a reference line index for a coding unit, wherein the coding unit is associated with a plurality of reference lines, and wherein the plurality of reference lines include a primary reference line and one or more additional reference lines that are located further away from the coding unit than the primary reference line;
when the reference line index is set to zero to indicate the primary reference line only, determine a first intra-prediction mode for the coding unit from an intra-prediction mode list; and
when the reference line index is set to a non-zero value to indicate one of the additional reference lines, determine a second intra-prediction mode for the coding unit only from a subset of the intra-prediction mode list, wherein the subset of the intra-prediction mode list includes modes associated with a most probable mode (MPM) list.

10. The video coding device of claim 9 , wherein candidate intra-predication modes in the MPM list include intra-prediction modes used by neighbor coding units of the coding unit.

11. The video coding device of claim 9 , wherein the processor is further configured to decode the coding unit by obtaining a block prediction value based on the first intra-prediction mode or the second intra-prediction mode and the plurality of reference lines.

12. The video coding device of claim 9 , wherein a value of the reference line index is inferred to be equal to zero when not present.

13. The video coding device of claim 9 , wherein the subset of the intra-prediction mode list includes a starting directional intra-prediction mode (DirS), an ending directional intra-prediction mode (DirE), and every Nth directional intra-prediction mode between DirS and DirE, where N is a predetermined integer value.

14. The video coding device of claim 13 , wherein the subset of the intra-prediction mode list further includes planar prediction mode and Direct Current (DC) prediction mode.

15. The video coding device of claim 9 , wherein the subset of the intra-prediction mode list includes a starting directional intra-prediction mode (DirS), an ending directional intra-prediction mode (DirE), a middle directional intra-prediction mode (DirD), a horizontal directional intra-prediction mode (DirH), a vertical directional intra-prediction mode (DirV), and valid directional intra-prediction modes at directions of plus or minus N of DirS, DirE, DirD, DirH, and DirV, where N is a predetermined integer value.

16. The video coding device of claim 15 , wherein the subset of the intra-prediction mode list further includes planar prediction mode and Direct Current (DC) prediction mode.

17. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to:
obtain a reference line index for a coding unit, wherein the coding unit is associated with a plurality of reference lines, and wherein the plurality of reference lines include a primary reference line and one or more additional reference lines that are located further away from the coding unit than the primary reference line;
when the reference line index is set to zero to indicate the primary reference line only, determine a first intra-prediction mode for the coding unit from an intra-prediction mode list; and
when the reference line index is set to a non-zero value to indicate one of the additional reference lines, determine a second intra-prediction mode for the coding unit only from a subset of the intra-prediction mode list, wherein the subset of the intra-prediction mode list includes modes associated with a most probable mode (MPM) list.

18. The video coding device of claim 17 , wherein candidate intra-predication modes in the MPM list include intra-prediction modes used by neighbor coding units of the coding unit.

19. The video coding device of claim 17 , wherein the computer executable instructions further cause the video coding device to decode the coding unit by obtaining a block prediction value based on the first intra-prediction mode or the second intra-prediction mode and the plurality of reference lines.

20. The video coding device of claim 17 , wherein a value of the reference line index is inferred to be equal to zero when not present.

Assignees

• Futurewei Technologies Inc

Inventors

• Liu Shan
• Ma Xiang

Classifications

• H04N19/463

  by compressing encoding parameters before transmission · CPC title

• H04N19/18

  the unit being a set of transform coefficients · CPC title

• H04N19/157

  Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter · CPC title

• H04N19/182

  the unit being a pixel · CPC title

• H04N19/593

  involving spatial prediction techniques · CPC title