Variable length coding table selection based on block type statistics for refinement coefficient coding
This disclosure describes techniques for coding an enhancement layer in a scalable video coding (SVC) scheme. The techniques may be used in variable length coding of refinement coefficients of an enhancement layer of a SVC scheme. According to this disclosure, a method may comprise determining first statistics associated with a first type of video block. determining second statistics associated with a second type of video block, selecting a first variable length coding (VLC) table from a plurality of VLC tables to be used in coding the first type of video block based on the first statistics, selecting a second VLC table from the plurality of VLC tables to be used in coding the second type of video block based on the second statistics, coding video blocks of the first type based on the first VLC table, and coding video blocks of the second type based on the second VLC table.
1. A method of coding an enhancement layer of a scalable video coding (SVC) scheme, the method comprising:
determining a first ratio associated with a first type of video block;
determining a second ratio associated with a second type of video block, wherein the first and second ratios are based on symbols indicating whether signs of refinement coefficients have changed or stayed the same relative to corresponding coefficients of a previous layer in the SVC scheme;
selecting a first variable length coding (VLC) table from a plurality of VLC tables to be used in coding the first type of video block based on the first ratio;
selecting a second VLC table from the plurality of VLC tables to be used in coding the second type of video block based on the second ratio;
coding video blocks of the first type based on the first VLC table; and
coding video blocks of the second type based on the second VLC table.
2. The method of claim 1 , wherein:
coding video blocks of the first type based on the first VLC table comprises encoding video blocks of the first type based on the first VLC table; and
coding video blocks of the second type based on the second VLC table comprises encoding video blocks of the second type based on the second VLC table.
3. The method of claim 1 , wherein:
coding video blocks of the first type based on the first VLC table comprises decoding video blocks of the first type based on the first VLC table; and
coding video blocks of the second type based on the second VLC table comprises decoding video blocks of the second type based on the second VLC table.
4. The method of claim 1 , wherein:
coding video blocks of the first type based on the first VLC table comprises performing table lookups using the first VLC table; and
coding video blocks of the second type based on the second VLC table comprises performing table lookups using the second VLC table.
5. The method of claim 1 , wherein the first type of the video block comprises an intra-coded video block and the second type of the video block comprises an inter-coded video block.
6. The method of claim 1 , wherein the video blocks are arranged in frames, wherein the method is repeated for each of the frames.
7. The method of claim 1 , wherein the method is performed with respect to refinement coefficients of the enhancement layer, wherein:
coding video blocks of the first type based on the first VLC table comprises coding refinement coefficients associated with video blocks of the first type; and
coding video blocks of the second type based on the second VLC table comprises coding refinement coefficients associated with video blocks of the second type.
8. The method of claim 7 , wherein:
the first and second ratios are ratios of symbols indicating whether previously coded refinement coefficients have a same sign value or an inverted sign value relative to the corresponding coefficients of the previous layer in the SVC scheme.
9. A non-transitory computer-readable medium comprising instructions that upon execution in a video coding device cause the device to code an enhancement layer of a scalable video coding (SVC) scheme, wherein the instructions cause the device to:
determine a first ratio associated with a first type of video block;
determine a second ratio associated with a second type of video block, wherein the first and second ratios are based on symbols indicating whether signs of refinement coefficients have changed or stayed the same relative to corresponding coefficients of a previous layer in the SVC scheme;
select a first variable length coding (VLC) table from a plurality of VLC tables to be used in coding the first type of video block based on the first ratio;
select a second VLC table from the plurality of VLC tables to be used in coding the second type of video block based on the second ratio;
code video blocks of the first type based on the first VLC table; and
code video blocks of the second type based on the second VLC table.
10. The non-transitory computer-readable medium of claim 9 , wherein:
the instructions that cause the video coding device to code video blocks of the first type based on the first VLC table cause the video coding device to encode video blocks of the first type based on the first VLC table; and
the instructions that cause the video coding device to code video blocks of the second type based on the second VLC table cause the video coding device to encode video blocks of the second type based on the second VLC table.
11. The non-transitory computer-readable medium of claim 9 , wherein:
the instructions that cause the video coding device to code video blocks of the first type based on the first VLC table comprise instructions that cause the video coding device to decode video blocks of the first type based on the first VLC table; and
the instructions that cause the video coding device to code video blocks of the second type based on the second VLC table cause the video coding device to decode video blocks of the second type based on the second VLC table.
12. The non-transitory computer-readable medium of claim 9 , wherein:
the instructions that cause the video coding device to code video blocks of the first type based on the first VLC table cause the video coding device to perform table lookups using the first VLC table; and
the instructions that cause the video coding device to code video blocks of the second type based on the second VLC table cause the video coding device to perform table lookups using the second VLC table.
13. The non-transitory computer-readable medium of claim 9 , wherein the first type of the video block comprises an intra-coded video block and the second type of the video block comprises an inter-coded video block.
14. The non-transitory computer-readable medium of claim 9 , wherein the video blocks are arranged in frames, and wherein the instructions are repeated for each of the frames.
15. The non-transitory computer-readable medium of claim 9 , wherein the instructions are performed with respect to refinement coefficients of the enhancement layer, wherein:
the instructions that cause the video coding device to code video blocks of the first type based on the first VLC table comprise the instructions that cause the video coding device to code refinement coefficients associated with video blocks of the first type; and
the instructions that cause the video coding device to code video blocks of the second type based on the second VLC table comprise the instructions that cause the video coding device to code refinement coefficients associated with video blocks of the second type.
16. The non-transitory computer-readable medium of claim 15 , wherein: the first and second ratios are ratios of symbols indicating whether previously coded refinement coefficients have a same sign value or an inverted sign value relative to the corresponding coefficients of the previous layer in the SVC scheme.