Method and appartus of adaptive loop filtering

Patent metadata

Field	Value
Publication number	US-9615093-B2
Application number	US-201514822026-A
Country	US
Kind code	B2
Filing date	Aug 10, 2015
Priority date	May 10, 2010
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

A method and apparatus receives input data for in-loop processing, where the input data corresponds to reconstructed or reconstructed-and-deblocked coding units of the picture. The input data is divided into multiple filter units and each filter unit includes one or more boundary-aligned reconstructed or reconstructed-and-deblocked coding units. A candidate filter is then selected from a candidate filter set for the in-loop processing. The candidate filter set comprises at least two candidate filters the said in-loop processing corresponding to adaptive loop filter (ALF), adaptive offset (AO), or adaptive clipping (AC). The in-loop processing is then applied to one of the filter units to generate a processed filter unit by using the candidate filter selected to all boundary-aligned reconstructed or reconstructed-and-deblocked coding units in said one of the filter units.

First claim

The invention claimed is:

1. A method for processing video using in-loop processing, wherein a picture is partitioned into coding units for applying coding process to each coding unit, the method comprising:
receiving input data to said in-loop processing, wherein the input data corresponds to reconstructed or reconstructed-and-deblocked coding units of the picture;
dividing the input data into multiple filter units, wherein at least one filter unit includes two or more boundary-aligned reconstructed or reconstructed-and-deblocked coding units;
selecting a candidate filter from a candidate filter set for said in-loop processing, wherein the candidate filter set comprises at least two candidate filters for said in-loop processing corresponding to adaptive loop filter (ALF), adaptive offset (AO), or adaptive clipping (AC);
applying said in-loop processing to said at least one filter unit including said two or more boundary-aligned reconstructed or reconstructed-and-deblocked coding units using the candidate filter selected to generate a processed filter unit by using the candidate filter selected to all boundary-aligned reconstructed or reconstructed-and-deblocked coding units in said at least one filter unit; and
providing processed video data comprising the processed filter unit.

2. The method of claim 1 , wherein boundaries of the filter units are also boundaries of the coding units.

3. The method of claim 1 , wherein two or more of the filter units are merged as indicated by a merge index to share the candidate filter selected from the candidate filter set.

4. The method of claim 3 , wherein said two or more of the filter units are spatially neighboring filter units, wherein said spatially neighboring filter units are formed by path scanning through the filter units using a scan pattern selected from a group consisting of horizontal scan, vertical scan, z-scan, snake scan, Hilbert scan, a pre-defined scan pattern, and a user-defined scan pattern.

5. The method of claim 4 , wherein information associated with the scan pattern, a choice of whether to allow use of the merge index, or both are incorporated in a sequence level, a picture level, a slice level, a coding unit level, a filter unit level or a filter control unit level.

6. The method of claim 1 , wherein each of the filter units is further partitioned into third blocks corresponding to filter control units, and a filter control flag is associated with each of the filter control units to select one filter from the candidate filter set for applying said in-loop processing.

7. The method of claim 6 , wherein each of filter units is partitioned into filter control units using quadtree partitioning, bock partitioning, prediction unit synchronized partitioning, or transform unit synchronized partitioning.

8. The method of claim 7 , wherein the filter control flag is used to indicate filter ON/OFF control when one filter is selected for the filter unit or the filter control flag is used to indicate one of multiple filters when more than one filter are selected for the filter unit.

9. The method of claim 1 , wherein the input data corresponds to a first reconstructed or constructed-and-deblocked color component and a second reconstructed or constructed-and-deblocked color component, and the first reconstructed or constructed-and-deblocked color component and the second reconstructed or constructed-and-deblocked color component share filter information associated with said in-loop processing, and the filter information shared corresponds to filter control unit partitioning, filter selection, filter control flag, filter shape, filter coefficients, or a combination of the above.

10. The method of claim 9 , wherein whether to share the filter information associated with said in-loop processing by the first reconstructed or constructed-and-deblocked color component and the second reconstructed or constructed-and-deblocked color component is enabled or disable according to a sharing switch.

11. The method of claim 10 , wherein information associated with the sharing switch is incorporated in a sequence level, a picture level, a slice level, a coding unit level, a filter unit level or a filter control unit level.

12. The method of claim 10 , wherein the filter information associated with said in-loop processing for the second reconstructed or constructed-and-deblocked color component is derived from the filter information associated with said in-loop processing for the first reconstructed or constructed-and-deblocked color component.

13. The method of claim 1 , wherein filter information associated with said in-loop processing is explicitly incorporated in a bitstream or is derived implicitly based on the input data according to a selection method.

14. The method of claim 13 , wherein the selection method is indicated by a syntax element in a sequence level, a picture level, a slice level, a coding unit level, a filter unit level or a filter control unit level.

15. The method of claim 14 , wherein the input data is classified into multiple categories using classification, and one filter is selected from the candidate filter set for each of the categories, the classification is based on a first characteristic derived from the input data, wherein the first characteristic is selected from a first group consisting of pixel intensity, edge activity, edge orientation, edge intensity, mode information, quantization parameter, residual energy, regional feature, motion information, and a combination of the above.

16. The method of claim 15 , wherein more than one first characteristics are adaptively selected for the classification according to a classifier indicator, wherein the classifier indicator is incorporated in a sequence level, a picture level, a slice level, a coding unit level, a filter unit level or a filter control unit level.

17. The method of claim 15 , wherein said multiple categories are further classified using a second characteristic derived from the input data, wherein the second characteristic is selected from a second group consisting of pixel intensity, edge activity, edge orientation, edge intensity, mode information, quantization parameter, residual energy, regional feature, motion information, and a combination of the above, and wherein the second characteristic is different from the first characteristic.

18. The method of claim 15 , wherein the regional feature is derived according to the characteristics for the filter unit, the coding unit or a pixel location.

19. An apparatus for processing video using in-loop processing, wherein a picture is partitioned into coding units for applying coding process to each coding unit, the apparatus comprising one or more electronic devices configured to:
receive input data to said in-loop processing, wherein the input data corresponds to reconstructed or reconstructed-and-deblocked coding units of the picture;
divide the input data into multiple filter units, wherein at least one filter unit includes two or more boundary-aligned reconstructed or reconstructed-and-deblocked coding units;
select a candidate filter from a candidate filter set for said in-loop processing, wherein the candidate filter set comprises at least two candidate filters for said in-loop processing corresponding to adaptive loop filter (ALF), adaptive offset (AO), or adaptive clipping (AC);
apply said in-loop processing to said at least one filter unit including said two or more boundary-aligned reconstructed or reconstructed-and-deblocked coding units using the candidate filter s

Assignees

• Hfi Innovation Inc

Inventors

• Fu Chih-Ming
• Chen Ching-Yeh
• Tsai Chia-Yang
• Huang Yu-Wen
• Lei Shaw-Min

Classifications

• H04N19/176

  the region being a block, e.g. a macroblock · CPC title

• H04N19/463

  by compressing encoding parameters before transmission · CPC title

• H04N19/159 Primary

  Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction · CPC title

• H04N19/119

  Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks · CPC title

• H04N19/10

  using adaptive coding · CPC title