Intra-prediction with multiple reference lines
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.
1. A video coding device comprising:
a receiver configured to receive a bitstream;
a processor coupled to the receiver and configured to:
determine a value of a reference line index of a coding unit;
determine an intra-prediction mode from a list of most probable modes when a value of the reference line index indicates an additional reference line; and
decode the coding unit based on the intra-prediction mode.
2. The video coding device of claim 1 , wherein the processor is further configured to determine an intra-prediction mode from a group of modes that excludes a list of most probable modes when the value of the reference line index indicates a primary reference line.
3. The video coding device of claim 2 , wherein the list of most probable modes are signaled by a most probable mode index when the value of the reference line index indicates an additional reference line.
4. The video coding device of claim 2 , wherein the group of modes that excludes the list of most probable modes are indexed by an intra-prediction mode index.
5. The video coding device of claim 2 , wherein the list of most probable modes includes intra-prediction modes used by neighbor coding units.
6. The video coding device of claim 1 , wherein the value of the reference line index is inferred to be equal to zero when not present.
7. 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:
receive a bitstream;
determine a value of a reference line index of a coding unit;
determine an intra-prediction mode from a list of most probable modes when a value of the reference line index indicates an additional reference line; and
decode the coding unit based on the intra-prediction mode.
8. The video coding device of claim 7 , wherein the processor is further configured to determine an intra-prediction mode from a group of modes that excludes a list of most probable modes when the value of the reference line index indicates a primary reference line.
9. The video coding device of claim 8 , wherein the list of most probable modes are signaled by a most probable mode index when the value of the reference line index indicates an additional reference line.
10. The video coding device of claim 8 , wherein the group of modes that excludes the list of most probable modes are indexed by an intra-prediction mode index.
11. The video coding device of claim 8 , wherein the list of most probable modes includes intra-prediction modes used by neighbor coding units.
12. The video coding device of claim 7 , wherein the value of the reference line index is inferred to be equal to zero when not present.
13. A video coding device comprising:
a processor configured to:
determine a value of a reference line index of a coding unit;
determine an intra-prediction mode from a list of most probable modes when a value of the reference line index indicates an additional reference line;
encode the coding unit into a bitstream based on the intra-prediction mode; and
a memory coupled to the processor and configured to store the bitstream.
14. The video coding device of claim 13 , wherein the processor is further configured to determine an intra-prediction mode from a group of modes that excludes a list of most probable modes when the value of the reference line index indicates a primary reference line.
15. The video coding device of claim 14 , wherein the list of most probable modes are signaled by a most probable mode index when the value of the reference line index indicates an additional reference line.
16. The video coding device of claim 14 , wherein the group of modes that excludes the list of most probable modes are indexed by an intra-prediction mode index.
17. The video coding device of claim 14 , wherein the list of most probable modes includes intra-prediction modes used by neighbor coding units.
18. The video coding device of claim 13 , wherein the value of the reference line index is omitted from the bitstream when the value of the reference line index is equal to zero.