Conditional predictive multi-symbol run-length coding
Conditional predictive multi-symbol run-length coding may include generating a differential residual block based on a residual block and a reconstructed residual block, entropy encoding the differential residual block by determining a symbol order for a plurality of symbols in the differential residual block, grouping the plurality of symbols into at least a first group and a second group based on the symbol order, run-length encoding the plurality of symbols in the differential residual block, by on a condition that a first symbol from the plurality of symbols is associated with the first group, encoding a second symbol from the plurality of symbols, and on a condition that the first symbol is associated with the second group, modifying the second symbol and encoding the modified second symbol.
1. A method for encoding a video stream including a plurality of frames, the method comprising:
generating a residual block based on a current block from a current frame from the plurality of frames;
generating a reconstructed residual block based on the residual block;
generating a differential residual block based on the residual block and the reconstructed residual block;
entropy encoding the differential residual block by:
determining a symbol order for a plurality of symbols in the differential residual block,
grouping the plurality of symbols into at least a first group and a second group based on the symbol order,
run-length encoding the plurality of symbols in the differential residual block, wherein run-length encoding includes:
on a condition that a first symbol from the plurality of symbols is associated with the first group, encoding a second symbol from the plurality of symbols, and
on a condition that the first symbol is associated with the second group, modifying the second symbol and encoding the modified second symbol; and
transmitting or storing an output including the encoded differential residual block wherein entropy encoding the differential residual block includes: associating the first group with a first plurality of code words such that each symbol associated with the first group is represented by a respective code word in the first plurality of code words; associating the second group with a second plurality of code words such that each symbol associated with the second group is represented by a respective code word in the second plurality of code words, wherein at least one code word from the first plurality of code words matches a code word from the second plurality of code words.
2. The method of claim 1 , wherein modifying the second symbol includes: on a condition that the first symbol is greater than zero, decreasing the second symbol by one less than the first symbol; and
on a condition that the first symbol is less than zero, decreasing the second symbol by one more than the first symbol.
3. The method of claim 1 , wherein modifying the second symbol includes associating the second symbol with the first group.
4. The method of claim 1 , wherein determining the symbol order includes:
using a default symbol order as the symbol order; and
selectively reordering a symbol in the symbol order.
5. The method of claim 1 , wherein transmitting or storing the output includes indicating the symbol order in a frame header, a slice header, a segment header, a macroblock header, or a block header.
6. The method of claim 1 , wherein grouping the plurality of symbols includes associating three symbols from the plurality of symbols with the first group.
7. The method of claim 1 , wherein run-length encoding includes including a run-length indicator in the output.
8. The method of claim 1 , wherein run-length encoding includes determining a run-length indicator based on a cardinality of consecutive symbols associated with the first group.
9. The method of claim 1 , wherein transmitting or storing the output includes indicating a maximum run-length in a frame header, a slice header, a segment header, a macroblock header, or a block header.
10. The method of claim 9 , wherein transmitting or storing the output does not include indicating a maximum run-length on a condition that the maximum run-length is inferable based on a default word-length.
11. A method for encoding a video stream including a plurality of frames, the method comprising:
generating a residual block based on a current block from a current frame from the plurality of frames;
generating a reconstructed residual block based on the residual block;
generating a differential residual block based on the residual block and the reconstructed residual block;
entropy encoding the differential residual block by:
determining a symbol order for a plurality of symbols in the differential residual block,
grouping the plurality of symbols into at least a first group and a second group based on the symbol order,
run-length encoding the plurality of symbols in the differential residual block, wherein run-length encoding includes:
determining a run-length indicator based on a cardinality of consecutive symbols associated with the first group,
on a condition that a first symbol from the plurality of symbols is associated with the first group, encoding a second symbol from the plurality of symbols, and
on a condition that the first symbol is associated with the second group, modifying the second symbol and encoding the modified second symbol wherein modifying the second symbol includes:
on a condition that the first symbol is greater than zero, decreasing the second symbol by one less than the first symbol; and
on a condition that the first symbol is less than zero, decreasing the second symbol by one more than the first symbol; and
transmitting or storing an output including the encoded differential residual block wherein entropy encoding the differential residual block includes: associating the first group with a first plurality of code words such that each symbol associated with the first group is represented by a respective code word in the first plurality of code words; associating the second group with a second plurality of code words such that each symbol associated with the second group is represented by a respective code word in the second plurality of code words, wherein at least one code word from the first plurality of code words matches a code word from the second plurality of code words.
12. The method of claim 11 , wherein modifying the second symbol includes associating the second symbol with the first group.
13. The method of claim 11 , wherein determining the symbol order includes: using a default symbol order as the symbol order; and
selectively reordering a symbol in the symbol order.
14. The method of claim 11 , wherein transmitting or storing the output includes indicating the symbol order in a frame header, a slice header, a segment header, a macroblock header, or a block header.
15. The method of claim 11 , wherein run-length encoding includes including the run-length indicator in the output.
16. The method of claim 11 , wherein transmitting or storing the output includes indicating a maximum run-length indicator in a frame header, a slice header, a segment header, a macroblock header, or a block header.
17. The method of claim 11 , wherein transmitting or storing the output does not include indicating a maximum run-length on a condition that the maximum run-length is inferable based on a default word-length.
18. A method for encoding a video stream including a plurality of frames, the method comprising:
generating a differential residual block based on a residual block and a reconstructed residual block;
entropy encoding the differential residual block using run-length encoding based on groupings of a plurality of symbols from the differential residual block, wherein run-length encoding includes:
on a condition that a first symbol from the plurality of symbols is associated with a first group, encoding a second symbol from the plurality of symbols, and
on a condition that the first symbol is associated with a second group, modifying the second symbol and encoding the modified second symbol; and transmitting or storing an output including the encoded differential residual block wherein entropy encoding the differential residual block includes: associating the first group with a first plurality of code words such that each symbol associated with the first group is represented by a respective code word in the first plurality of code words; associating the second group with a second plurality of code words such that each symbol associated with the second group is represented by a respective code word in the second plurality of code words, wherein at least one code word from the first plurality of code words matches a code word from the second plurality of code words.