METHOD AND APPARATUS FOR ENCODING VIDEO BY PERFORMING IN-LOOP FILTERING BASED ON TREE-STRUCTURED DATA UNIT, AND METHOD AND APPARATUS FOR DECODING VIDEO BY PERFORMING THE SAME

• US 20110243249A1
• Filed: 04/05/2011
• Published: 10/06/2011
• Est. Priority Date: 04/05/2010
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: CHOI, Byeong-doo, LEE, Tammy, HAN, Woo-jin
• Application Number:
  US13/080,209
• Publication Number:
  US 20110243249A1
• Time in Patent Office: Days
• US Class Current: 375/240.25
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/119 Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
• CPC Class Codes: H04N 19/122 Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/157 Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness
• CPC Class Codes: H04N 19/96 Tree coding, e.g. quad-tree coding

Abstract

An apparatus and method of encoding and an apparatus and method of decoding a video by performing in-loop filtering based on coding units are provided. The encoding method includes: splitting a picture into a maximum coding unit; separately determining coding units for outputting encoding results according to a coded depth for deeper coding units that are hierarchically structured according to depths indicating a number of times the coding units are spatially split from the maximum coding unit, wherein the coding units are hierarchical according to the depths in a same region in the maximum coding unit and are independent according to the coded depth in other regions; and determining a filtering unit for performing in-loop filtering so as to minimize an error between the maximum coding unit and an original picture, based on the coding units, and performing in-loop filtering based on the filtering unit.

Claims

1. A method of encoding a video by performing in-loop filtering based on coding units, the method comprising:

splitting a picture into a maximum coding unit that is a data unit, wherein the maximum coding unit has a maximum size;

separately determining coding units to output encoding results according to a coded depth for deeper coding units that are hierarchically structured according to depths indicating a number of times the coding units are spatially split from the maximum coding unit, the coding units determined according to a tree-structure, wherein the coding units are hierarchical according to the depths in one region in the maximum coding unit and are independent according to the coded depth in other regions;

determining a filtering unit to perform in-loop filtering so as to minimize an error between the maximum coding unit and an original picture, based on the coding units according to the tree-structure of the maximum coding unit; and

performing the in-loop filtering based on the determined filtering unit.

2. The method of claim 1, wherein the determining the filtering unit comprises determining the filtering unit based on the coding units according to the tree-structure of the maximum coding unit.

3. The method of claim 1, wherein the determining the filtering unit comprises determining the filtering unit based on the coding units according to the tree-structure of the maximum coding unit and based on partitions that are data units for prediction encoding of each coding unit according to a coded depth.

4. The method of claim 2, wherein the determining the filtering unit based on the coding units comprises determining a data unit as the filtering unit, wherein the data unit is obtained by splitting or merging one or more of the coding units according to the tree-structure.

5. The method of claim 2, wherein the determining the filtering unit based on the coding units comprises using the coding units according to the tree-structure as prediction values of the filtering unit.

6. The method of claim 2, wherein the determining the filtering unit based on the coding units comprises determining a filtering layer from among layers according to depths of the coding units according to the tree-structure, and determining hierarchical data units up to the determined filtering layer as the filtering unit.

7. The method of claim 6, wherein the filtering layer is determined as one of layers from an initial layer of the maximum coding unit to a final layer indicating a lowermost depth from among the coding units according to the tree-structure of the maximum coding unit.

8. The method of claim 7, wherein the filtering layer is determined as one of layers from an upper-limit layer to a lower-limit layer set between the initial layer and the final layer.

9. The method of claim 2, further comprising encoding information about the in-loop filtering and transmitting the encoded information about the in-loop filtering, encoded data of the picture, and encoded mode information about the coding units according to the tree-structure of the maximum coding unit, according to the filtering unit.

10. The method of claim 7, wherein the information about the in-loop filtering comprises at least one of filtering layer information about a filtering layer determined as one of layers of the deeper coding units so as to determine filtering units with respect to the coding units according to the tree-structure, in-loop filtering performance information indicating performance of the in-loop filtering for the filtering units, filter coefficient information for the in-loop filtering, and information about an upper-limit layer and a lower-limit layer of the filtering layer.

11. The method of claim 2, wherein the performing the in-loop filtering comprises setting in-loop filtering performance information indicating performance of the in-loop filtering for the filtering unit.

12. The method of claim 2, wherein the determining the filtering unit based on the coding units comprises separately determining a filtering unit for a luma component of a color component, and a filtering unit for a chroma component of the color component.

13. The method of claim 2, wherein the determining the filtering unit based on the coding units comprises predicting a filtering unit for a chroma component by referring to a filtering unit for a luma component of a color component.

14. The method of claim 2, wherein the determining the filtering unit based on the coding units comprises applying a same filtering unit to all of maximum coding units in the picture.

15. The method of claim 2, wherein filtering units are separately determined according to one of data units comprising the picture, a sequence of the picture, a frame, a field, and a maximum coding unit.

16. The method of claim 2, wherein the performing the in-loop filtering comprises performing the in-loop filtering by selecting a filter type from among a plurality of filter types.

17. The method of claim 16, wherein:

the performing the in-loop filtering further comprises setting in-loop filtering performance information for each of filtering units; and

the in-loop filtering performance information indicates performance of the in-loop filtering and indicates the filter type selected from the plurality of filter types.

18. The method of claim 11, wherein the in-loop filtering performance information comprises a flag for distinguishing a case in which in-loop filtering using a predetermined filter type is performed from a case in which in-loop filtering using the predetermined filter type is not performed.

19. The method of claim 11, wherein the in-loop filtering performance information is set so as to distinguish between filter types classified according to predetermined image characteristics of filtering units.

20. The method of claim 11, wherein the in-loop filtering performance information is set so as to distinguish between filter types classified according to coding symbols of filtering units.

21. The method of claim 2, wherein the performing the in-loop filtering comprises generating a filter coefficient so as to perform the in-loop filtering on the filtering unit.

22. The method of claim 9, wherein the transmitting comprises inserting the in-loop filtering information into a Sequence Parameter Set (SPS) or a Picture Parameter Set (PPS) of the picture and transmitting the inserted in-loop filtering information.

49. A computer readable recording medium having recorded thereon a program for executing the method of encoding of claim 1.

23. A method of decoding a video by performing in-loop filtering based on coding units, the method comprising:

parsing a received bitstream and extracting image data encoded for each of coding units based on the coding units according to a tree-structure which are comprised in a maximum coding unit obtained by splitting a current picture, extracting encoded mode information about the coding units according to the tree-structure, and extracting information about in-loop filtering of the maximum coding unit;

decoding the extracted image data, based on the extracted encoded mode information which is extracted for the maximum coding unit;

determining, using the extracted information about in-loop filtering, a filtering unit for the in-loop filtering based on the coding units according to the tree-structure of the maximum coding unit; and

performing the in-loop filtering on the decoded image data of the maximum coding unit according to the filtering unit.

24. The method of claim 23, wherein the determining the filtering unit comprises determining the filtering unit based on the coding units according to the tree-structure of the maximum coding unit, by referring to the extracted information about in-loop filtering.

25. The method of claim 23, wherein the determining the filtering unit comprises determining the filtering unit based on the coding units according to the tree-structure of the maximum coding unit and based on partitions that are data units for prediction encoding of each coding unit according to a coded depth, by referring to the extracted information about in-loop filtering.

26. The method of claim 24, wherein the determining the filtering unit based on the coding units comprises determining a data unit as the filtering unit, wherein the data unit is obtained by splitting or merging one or more of the coding units according to the tree-structure, by referring to the extracted information about in-loop filtering.

27. The method of claim 24, wherein the determining the filtering unit based on the coding units comprises using the coding units according to the tree-structure as prediction values of the filtering unit, by referring to the extracted information about in-loop filtering.

28. The method of claim 24, wherein the information about the in-loop filtering comprises at least one of filtering layer information about a filtering layer determined as one of layers of the deeper coding units so as to determine filtering units with respect to the coding units according to the tree-structure, in-loop filtering performance information indicating performance of the in-loop filtering for the filtering units, filter coefficient information for the in-loop filtering, and information about an upper-limit layer and a lower-limit layer of the filtering layer.

29. The method of claim 28, wherein the determining the filtering unit comprises determining hierarchical data units up to the filtering layer as the filtering unit, according to the filtering layer information.

30. The method of claim 28, wherein the filtering layer is determined as one of layers from an initial layer of the maximum coding unit to a final layer indicating a lowermost depth from among the coding units according to the tree-structure of the maximum coding unit.

31. The method of claim 30, wherein the filtering layer is determined as one of layers from an upper-limit layer to a lower-limit layer set between the final layer and the initial layer of the maximum coding unit.

32. The method of claim 28, wherein the performing the in-loop filtering comprises determining performance of in-loop filtering for each of the coding units according to the tree-structure of the maximum coding unit, based on the in-loop filtering performance information.

33. The method of claim 24, wherein:

the determining the filtering unit based on the coding units comprises separately determining a filtering unit for a luma component of a color component and a filtering unit for a chroma component of the color component according to in-loop filtering performance information; and

the performing the in-loop filtering comprises performing the in-loop filtering for each of the luma component and the chroma component.

34. The method of claim 24, wherein:

the determining the filtering unit based on the coding units comprises predicting a filtering unit for a chroma component by referring to a filtering unit for a luma component of a color component, according to in-loop filtering performance information; and

the performing the in-loop filtering comprises performing the in-loop filtering for each of the luma component and the chroma component.

35. The method of claim 24, wherein the determining the filtering unit based on the coding units comprises applying a same filtering unit to all of maximum coding units in the current picture.

36. The method of claim 24, wherein filtering units are separately determined according to one of data units comprising a picture, a sequence of the picture, a frame, a field, and a maximum coding unit.

37. The method of claim 28, wherein the performing the in-loop filtering comprises performing the in-loop filtering by selecting a filter type from among a plurality of filter types, based on the in-loop filtering performance information.

38. The method of claim 37, wherein the performing the in-loop filtering further comprises setting the in-loop filtering performance information for each of filtering units, based on the in-loop filtering performance information, and if the in-loop filtering is performed.

39. The method of claim 38, wherein the in-loop filtering performance information comprises a flag for distinguishing a case in which in-loop filtering using a predetermined filter type is performed from a case in which in-loop filtering using the predetermined filter type is not performed.

40. The method of claim 38, wherein the in-loop filtering performance information is set so as to distinguish between filter types classified according to predetermined image characteristics of the filtering units.

41. The method of claim 38, wherein the in-loop filtering performance information is set so as to distinguish between filter types classified according to coding symbols of the filtering units.

42. The method of claim 39, wherein the performing the in-loop filtering further comprises generating a filter coefficient so as to perform the in-loop filtering on the filtering unit, based on the filter coefficient information.

43. The method of claim 23, wherein the extracting comprises extracting the information about in-loop filtering, the encoded image data, and the encoded mode information about the coding units according to the tree-structure, according to the filtering unit.

44. The method of claim 23, wherein the extracting comprises extracting the information about in-loop filtering from a Sequence Parameter Set (SPS) or a Picture Parameter Set (PPS) of the picture.

45. The method of claim 23, wherein:

the coding units according to the tree-structure which are comprised in the maximum coding unit are hierarchical according to the depths in one region in the maximum coding unit and are independent according to the coded depth in other regions; and

the coding units are determined to independently output encoding results according to a coded depth for deeper coding units that are hierarchically structured according to depths indicating a number of times the coding units are spatially split from the maximum coding unit.

46. The method of claim 23, further comprising performing prediction decoding on a next picture by referring to the current picture to which the in-loop filtering is performed.

50. A computer readable recording medium having recorded thereon a program for executing the method of decoding of claim 23.

47. A video encoding apparatus for encoding a video by performing in-loop filtering based on coding units, the video encoding apparatus comprising:

an encoding unit determining unit which splits a picture into a maximum coding unit that is a data unit, wherein the maximum coding unit has a maximum size, separately determines coding units to output encoding results according to a coded depth for deeper coding units that are hierarchically structured according to depths indicating a number of times the coding units are spatially split from the maximum coding unit, the coding units determined according to a tree-structure, wherein the coding units are hierarchical according to the depths in one region in the maximum coding unit and are independent according to the coded depth in other regions;

an in-loop filtering unit which determines a filtering unit to perform in-loop filtering so as to minimize an error between the maximum coding unit and an original picture, based on the coding units according to the tree-structure of the maximum coding unit, and performs the in-loop filtering based on the filtering unit; and

a transmitting unit which encodes information about the in-loop filtering and transmits the encoded information about the in-loop filtering, encoded data of the picture, and encoded mode information about the coding units according to the tree-structure of the maximum coding unit in units of filtering units.

48. A video decoding apparatus for decoding a video by performing in-loop filtering based on coding units, the video decoding apparatus comprising:

a receiving and extracting unit which parses a received bitstream and extracts image data encoded for each of coding units based on the coding units according to a tree-structure which are comprised in a maximum coding unit obtained by splitting a current picture, extracting encoded mode information about the coding units according to the tree-structure, and extracting information about in-loop filtering of the maximum coding unit;

a decoding unit which decodes the extracted image data, based on the extracted encoded mode information which is extracted for the maximum coding unit; and

an in-loop filtering performing unit which determines, using the information about in-loop filtering, a filtering unit for the in-loop filtering based on the coding units according to the tree-structure of the maximum coding unit, and performs the in-loop filtering on the decoded image data of the maximum coding unit according to the filtering unit.