Lossless coding technique for CABAC in HEVC

1. An apparatus, comprising:

an electronic device configured to:

obtain a block representing a residual sample for lossless encoding;

generate a significance map, wherein the generating includes populating a significance map field that corresponds to the last scanning position of the block with a value corresponding to a level of the last scanning position of the block;

generate a sequence of syntax elements including the significance map having the value; and

transmit a bitstream representing the generated sequence of syntax elements to a decoder.

2. The apparatus of claim 1 , wherein the sequence of syntax elements is generated without performing the last position coding step of Context Adaptive Binary Arithmetic Coding (CABAC).

3. The apparatus of claim 1 , wherein the electronic device is further configured to:

perform adaptive binarization using a plurality of binarization tables, wherein values of an Absolute −3 portion of the sequence of syntax elements are used as input values for the plurality of binarization tables; and

encode a result of the adaptive binarization.

4. The apparatus of claim 3 , wherein the plurality of binarization tables are VLC tables of CAVLC.

5. The apparatus of claim 4 , wherein the encoding the result of the adaptive binarization further comprises utilizing a CABAC bypassing coding mode.

6. The apparatus of claim 3 , wherein the adaptive binarization of the input values using the plurality of binarization tables further comprises:

determining whether one of the input values is greater than a preset threshold; and

performing a table update responsive to determining that said input value is greater than the preset threshold.

7. The apparatus of claim 1 , wherein electronic device is further configured to:

access only a subset of the context models of CABAC; and

use the subset of the context models to code the significance map.

8. The apparatus of claim 7 , where the subset comprises the context models of CABAC that do not represent frequency component(s).

9. An apparatus, comprising:

an electronic device configured to:

obtain a block representing a residual sample for lossless encoding;

generate a sequence of syntax elements to represent the block;

perform adaptive binarization using a plurality of binarization tables, wherein values of an Absolute −3 portion of the sequence of syntax elements are used as input values for the plurality of binarization tables;

encode a result of the adaptive binarization; and

transmit the encoding to a decoder.

10. The apparatus of claim 9 , wherein the plurality of binarization tables are VLC tables of CAVLC.

11. The apparatus of claim 10 , wherein encoding the result of the adaptive binarization further comprises utilizing a Context Adaptive Binary Arithmetic Coding (CABAC) bypassing coding mode.

12. The apparatus of claim 9 , wherein the adaptive binarization of the input values using the plurality of binarization tables further comprises:

determining whether one of the input values is greater than a preset threshold; and

performing a table update responsive to determining that said input value is greater than the preset threshold.

13. The apparatus of claim 9 , wherein the electronic device is further configured to:

generate a significance map, wherein the generating includes populating a significance map field that corresponds to the last scanning position of the block with a value corresponding to a level of the last scanning position of the block; and

generate the sequence of syntax elements using the generated significance map.

14. The apparatus of claim 9 , wherein the sequence of syntax elements is generated without performing the last position coding step of CABAC.

15. A method, comprising:

filtering the context models of Context Adaptive Binary Arithmetic Coding (CABAC) based on relationship to frequency component;

obtaining a bitstream;

recovering a binary symbol from the bitstream;

decoding the binary symbol using the filtered context models; and

recovering video data using a result of the decoding.

16. The method of claim 15 , further comprising:

recovering, from the bitstream, a sequence of syntax elements having a significance map populated with a value corresponding to a last scanning position of a block representing a residual sample; and

decoding the levels of the block using the significance map and using said value of the significance map.

17. The method of claim 16 , wherein the decoding of the levels of the block is performed without performing the last position decoding step of CABAC.

18. The method of claim 15 , further comprising:

bypass decoding the recovered binary symbol;

adaptively de-binarizing a result of the bypass decoding; and

recovering a block representing residual information using a result of the de-binarization.

19. The method of claim 18 , further comprising using a plurality of VLC tables of CAVLC for the adaptive de-binarization.

20. The method of claim 19 , wherein the bypass decoding further comprises utilizing a CABAC bypass decoding mode.