Coding enhancement in cross-component sample adaptive offset
An electronic apparatus performs a method of decoding video data. The method includes receiving, from a video bitstream having a hierarchical structure, a first syntax element associated with a first level of the hierarchical structure, in accordance with a determination that the first syntax element indicates that a Cross-Component Sample Adaptive Offset (CCSAO) filter information is present in the first level, reconstructing, from the video bitstream, one or more regions under the first level jointly according to the CCSAO filter information, and in accordance with a determination that the first syntax element indicates that the CCSAO filter information is not present in the first level, reconstructing, from the video bitstream, the one or more regions separately according to the CCSAO filter information present in a second level of the hierarchical structure.
1. A method of decoding video data, comprising:
receiving, from a video bitstream having a hierarchical structure, a first syntax element associated with a first level of the hierarchical structure; and
in accordance with a determination that the first syntax element indicates that a Cross-Component Sample Adaptive Offset (CCSAO) filter information is not present in the first level, reconstructing, from the video bitstream, one or more regions separately according to the CCSAO filter information present in a second level of the hierarchical structure.
2. The method of claim 1 , wherein reconstructing, from the video bitstream, the one or more regions separately according to the CCSAO filter information present in the second level of the hierarchical structure includes:
receiving, from the video bitstream, a second syntax element associated with the second level of the hierarchical structure under the first level; and
in accordance with a determination that the second syntax element indicates that the CCSAO filter information is present in the second level, reconstructing, from the video bitstream, the one or more regions separately according to a respective CCSAO filter information present in the second level of the hierarchical structure of a respective region of the one or more regions.
3. The method of claim 1 , wherein the first level of the hierarchical structure is a Picture Header (PH) syntax structure referring to Picture parameter set (PPS).
4. The method of claim 1 , wherein the second level of the hierarchical structure is a Slice Header (SH) syntax structure referring to Picture parameter set (PPS).
5. The method of claim 1 , wherein the CCSAO filter information includes one or more selected from a syntax element indicating whether CCSAO is enabled, a syntax element indicating which previously decoded offset set is used, a syntax element indicating whether to enable a component on/off control at coding tree block (CTB) level, a syntax element indicating a band number for a component of a corresponding class, a syntax element indicating an offset set number for a component of a corresponding class, a syntax element indicating an edge direction for a component of a corresponding class, a syntax element indicating whether a current component can use other components for classification, a syntax element indicating a component offset value of a corresponding class, a syntax element indicating number of alternative sets used in a picture/slice, or a syntax element indicating a classifier candidate position.
6. The method of claim 1 , wherein the CCSAO filter information includes:
a syntax element indicating a component offset sign value of a corresponding class, and a syntax element indicating a component offset absolute value of the corresponding class,
wherein the syntax element indicating the component offset sign value of the corresponding class is decoded from the video bitstream in response to a determination that the syntax element indicating the component offset absolute value of the corresponding class is not zero.
7. The method of claim 1 , further comprising:
receiving, from the video bitstream, a third syntax element;
in accordance with a determination that the third syntax element indicates that a constraint including a CCSAO filter being not enabled for pictures within a predefined output layer sets (OLSs) within the video bitstream, reconstructing, from the video bitstream, the one or more regions with the constraint; and
in accordance with a determination that the third syntax element indicates that the constraint does not apply, reconstructing, from the video bitstream, the one or more regions without the constraint.
8. The method of claim 1 , further comprising:
in accordance with a determination that the first syntax element indicates that the CCSAO filter information is present in the first level, reconstructing, from the video bitstream, the one or more regions under the first level jointly according to the CCSAO filter information.
9. The method of claim 8 , wherein the video bitstream comprises a first component and a second component, and reconstructing, from the video bitstream, the one or more regions according to the CCSAO filter information comprises:
in response to a CCSAO filter being applied,
determining a classifier for the second component from a set of one or more samples of the first component associated with a respective sample of the second component according to the CCSAO filter information;
determining whether to modify a value of the respective sample of the second component within a region of the one or more regions of the video bitstream according to the classifier;
in response to the determination to modify the value of the respective sample of the second component within the region according to the classifier, determining a sample offset for the respective sample of the second component according to the classifier; and
modifying the value of the respective sample of the second component based on the sample offset that was determined.
10. The method of claim 9 , wherein the video bitstream further includes a third component, and each of the first component, the second component, and the third component is selected from one of YUV components or one of GBR components.
11. The method of claim 9 , wherein determining the sample offset for the respective sample of the second component according to the classifier includes determining a weighted sample offset for the respective sample of the second component according to the classifier.
12. The method of claim 9 , wherein determining the sample offset for the respective sample of the second component according to the classifier includes determining a sample offset for the respective sample of the second component according to a weighted sample offset of one or more classifiers.
13. An electronic apparatus comprising:
one or more processing units;
memory coupled to the one or more processing units; and
a plurality of programs stored in the memory that, when executed by the one or more processing units, cause the electronic apparatus to perform a method of for decoding video data, the method comprising:
receiving, from a video bitstream having a hierarchical structure, a first syntax element associated with a first level of the hierarchical structure; and
in accordance with a determination that the first syntax element indicates that a Cross-Component Sample Adaptive Offset (CCSAO) filter information is not present in the first level, reconstructing, from the video bitstream, one or more regions separately according to the CCSAO filter information present in a second level of the hierarchical structure.
14. The electronic apparatus according to claim 13 , the method performed by the electronic apparatus further comprising:
in accordance with a determination that the first syntax element indicates that the CCSAO filter information is present in the first level, reconstructing, from the video bitstream, the one or more regions under the first level jointly according to the CCSAO filter information.
15. The electronic apparatus according to claim 13 , the method performed by the electronic apparatus further comprising:
receiving, from the video bitstream, a third syntax element;
in accordance with a determination that the third syntax element indicates that a constraint including a CCSAO filter being not enabled for pictures within a predefined output layer sets (OLSs) within the video bitstream, reconstructing, from the video bitstream, the one or more regions with the constraint; and
in accordance with a determination that the third syntax element indicates that the constraint does not apply, reconstructing, from the video bitstream, the one or more regions without the constraint.
16. The electronic apparatus according to claim 13 , wherein the CCSAO filter information includes:
a syntax element indicating a component offset sign value of a corresponding class, and a syntax element indicating a component offset absolute value of the corresponding class,
wherein the syntax element indicating the component offset sign value of the corresponding class is decoded from the video bitstream in response to a determination that the syntax element indicating the component offset absolute value of the corresponding class is not zero.
17. A method for processing a bitstream, comprising:
storing a video bitstream
and decoding the video bitstream by a video decoding method,
wherein the video decoding method comprises:
receiving, from the video bitstream having a hierarchical structure, a first syntax element associated with a first level of the hierarchical structure; and
in accordance with a determination that the first syntax element indicates that a Cross-Component Sample Adaptive Offset (CCSAO) filter information is not present in the first level, reconstructing, from the video bitstream, one or more regions separately according to the CCSAO filter information present in a second level of the hierarchical structure.
18. The method according to claim 17 , the video decoding method further comprising:
in accordance with a determination that the first syntax element indicates that the CCSAO filter information is present in the first level, reconstructing, from the video bitstream, the one or more regions under the first level jointly according to the CCSAO filter information.
19. The method according to claim 17 , the video decoding method further comprising:
receiving, from the video bitstream, a third syntax element;
in accordance with a determination that the third syntax element indicates that a constraint including a CCSAO filter being not enabled for pictures within a predefined output layer sets (OLSs) within the video bitstream, reconstructing, from the video bitstream, the one or more regions with the constraint; and
in accordance with a determination that the third syntax element indicates that the constraint does not apply, reconstructing, from the video bitstream, the one or more regions without the constraint.
20. The method according to claim 17 , wherein the CCSAO filter information includes:
a syntax element indicating a component offset sign value of a corresponding class, and a syntax element indicating a component offset absolute value of the corresponding class,
wherein the syntax element indicating the component offset sign value of the corresponding class is decoded from the bitstream in response to a determination that the syntax element indicating the component offset absolute value of the corresponding class is not zero.