Joint intra mode coding
The various implementations described herein include methods and systems for coding video. In one aspect, a method includes receiving a video bitstream comprising a plurality of blocks. The method also includes identifying, by parsing a single syntax from the video bitstream, two or more parameters associated with an intra prediction mode for a first block in the plurality of blocks. The method further includes reconstructing the first block using the intra prediction mode and the two or more parameters.
1 . A method of video decoding performed at a computing system having memory and one or more processors, the method comprising:
receiving a video bitstream comprising method of video decoding performed at a computing system having memory and one or more processors, the method comprising:
receiving a video bitstream comprising a plurality of blocks;
identifying, by parsing a single syntax from the video bitstream, two or more parameters associated with an intra prediction mode for a first block in the plurality of blocks; and
generating an entry for a look-up table based on coded information of one or more previously decoded blocks;
reconstructing the first block using the intra prediction mode and the two or more parameters, wherein the two or more parameters are identified using a value of the single syntax and the look-up table, wherein an intra prediction mode of a left neighboring block is combined with a reference line index of an above neighboring block to generate the entry for the look-up table that contains both the intra prediction mode and the reference line index, or wherein an angular intra prediction mode of a second block that includes an angle delta offset value is combined with a reference line index of a third block to generate the entry for the look-up table that contains both the angle delta offset value and the reference line index.
2 . The method of claim 1 , wherein the two or more parameters comprise a reference line index and an index for the intra prediction mode.
3 . The method of claim 2 , wherein the intra prediction mode is for a luma component of the first block.
4 . The method of claim 2 , wherein:
when a luma component and a chroma component of the first block share one or more of a same block partitioning, and a same transform partitioning, the intra prediction mode corresponds to the luma component and the chroma component; and
when the luma component and the chroma component do not share the same block partitioning, or the same transform partitioning, the intra prediction mode corresponds to only the luma component.
5 . The method of claim 1 , wherein the two or more parameters are identified using a value of the single syntax and a look-up table.
6 . The method of claim 5 , further comprising populating the look-up table using intra prediction mode indicators of one or more previously decoded blocks.
7 . The method of claim 5 , wherein:
an entry in the look-up table corresponds to a cross-component chroma prediction mode; and
when the entry in the look-up table is selected for the first block, an additional indicator in the video bitstream is signaled to indicate the single syntax that is used for coding the first block.
8 . The method of claim 1 , wherein the two or more parameters are identified by parsing the single syntax when an indicator in the video bitstream indicates that the two or more parameters are signaled jointly; and
the method further comprising, when the indicator in the video bitstream indicates that the two or more parameters are signaled separately, identifying the two or more parameters based on a plurality of syntax from the video bitstream.
9 . The method of claim 8 , wherein the indicator is signaled in a high-level syntax of the video bitstream.
10 . The method of claim 1 , further comprising determining, based on a first indicator in the video bitstream, whether intra mode parameters for all components are signaled jointly;
when the first indicator indicates that the intra mode parameters for all components are signaled jointly, the two or more parameters are identified by parsing the single syntax;
when the first indicator indicates that the intra mode parameters for all components are not signaled jointly, parsing a second indicator that indicates whether intra mode parameters for a current component are signaled jointly; and
when the second indicator indicates that the intra mode parameters for the current component are signaled jointly, the two or more parameters are identified by parsing the single syntax.
11 . The method of claim 1 , further comprising selecting a first look-up table from a set of look-up tables for use with the first block, wherein the two or more parameters are identified using a value of the single syntax and the first look-up table.
12 . The method of claim 11 , wherein the first look-up table is selected based on an indicator in the video bitstream.
13 . A computing system, comprising:
control circuitry;
memory; and
one or more sets of instructions stored in the memory and configured for execution by the control circuitry, the one or more sets of instructions comprising instructions for:
receiving video data comprising a plurality of blocks;
when two or more parameters associated with an intra prediction mode for a first block in the plurality of blocks are to be signaled jointly, signaling a single syntax in a video bitstream to indicate the two or more parameters; and generating an entry for a look-up table, wherein the two or more parameters are identified using a value of the single syntax and the look-up table, wherein an intra prediction mode of a left neighboring block is combined with a reference line index of an above neighboring block to generate the entry for the look-up table that contains both the intra prediction mode and the reference line index, or wherein an angular intra prediction mode of a second block that includes an angle delta offset value is combined with a reference line index of a third block to generate the entry for the look-up table that contains both the angle delta offset value and the reference line index;
when two or more parameters associated with an intra prediction mode for a first block in the plurality of blocks are to be signaled separately, signaling a separate syntax in the video bitstream to indicate each of the two or more parameters; and
encoding the first block using the intra prediction mode and the two or more parameters.
14 . The computing system of claim 13 , wherein the two or more parameters comprise a reference line index and an index for the intra prediction mode.
15 . The computing system of claim 13 , wherein the one or more sets of instructions further comprise instructions for signaling an indicator in the video bitstream that indicates whether the two or more parameters are signaled jointly.
16 . The computing system of claim 13 , wherein the one or more sets of instructions further comprise instructions for:
signaling a first indicator in the video bitstream that indicates whether intra mode parameters are signaled jointly for all components in a set of components; and
when the first indicator indicates that the intra mode parameters are not signaled jointly for all components in the set of components, signaling a second indicator in the video bitstream that indicates whether intra mode parameters are signaled jointly for a particular component in the set of components.
17 . A non-transitory computer-readable storage medium storing a video encoding method, the video encoding method comprising:
receiving video data comprising a plurality of blocks;
when two or more parameters associated with an intra prediction mode for a first block in the plurality of blocks are to be signaled jointly, signaling a single syntax in a video bitstream to indicate the two or more parameters; and generating an entry for a look-up table, wherein the two or more parameters are identified using a value of the single syntax and the look-up table, wherein an intra prediction mode of a left neighboring block is combined with a reference line index of an above neighboring block to generate the entry for the look-up table that contains both the intra prediction mode and the reference line index, or wherein an angular intra prediction mode of a second block that includes an angle delta offset value is combined with a reference line index of a third block to generate the entry for the look-up table that contains both the angle delta offset value and the reference line index;
when two or more parameters associated with an intra prediction mode for a first block in the plurality of blocks are to be signaled separately, signaling a separate syntax in the video bitstream to indicate each of the two or more parameters; and
encoding the first block using the intra prediction mode and the two or more parameters, wherein the video bitstream comprises a signaled single syntax, or separately signaled syntaxes to indicate each of the two or more parameters.