Apparatus and Method for High Efficiency Video Coding Using Flexible Slice Structure

• US 20120106652A1
• Filed: 12/13/2010
• Published: 05/03/2012
• Est. Priority Date: 11/01/2010
• Status: Active Grant

• Current Assignee: Communication Advances LLC (IP Edge LLC)
• Original Assignee: MediaTek, Inc.
• Inventors: Huang, Yu-Wen, Fu, Chih-Ming, Chen, Ching-Yeh, Hsu, Chih-Wei, Lei, Shaw-Min
• Granted Patent: US 8,654,860 B2
• Time in Patent Office: Days
• US Class Current: 375/240.25
• CPC Class Codes: H04N 19/174 the region being a slice, e.g. a line of blocks or a group of blocks
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

An apparatus and method for video coding based on flexible slice structure are disclosed. In the recent high efficiency video coding (HEVC) development, the slice may contain multiple LCUs instead of macroblocks. The LCU size being considered is 64×64 pixels which is much larger than the macroblock size of 16×16 pixels. Compared with the macroblock aligned slice for H.264, the LCU-aligned slice for HEVC does not provide enough granularities for dividing video frames. Consequently, a flexible slice structure is developed where slice partition is based on smaller coding units. In the flexible slice structure, the first LCU and the last LCU of the slice are allowed to be a fractional LCU, which is derived from a whole LCU using quadtree partition. Syntax elements are also developed to enable conveyance of flexible slice structure between an encoder and a decoder efficiently.

Claims

1. A method for video coding, the method comprising:

partitioning video input data into largest coding units (LCUs);

configuring a slice to include a plurality of LCUs, having a first LCU and a last LCU;

wherein the first LCU and the last LCU are selected from a group consisting of a fractional LCU and a whole LCU and wherein the fractional LCU is formed by partitioning the whole LCU into leaf CUs according to a quadtree;

applying video coding to the slice to generate compressed video data for the slice;

generating a slice layer bitstream comprising the compressed video data for the slice; and

generating a video bitstream comprising the slice layer bitstream.

2. The method of claim 1, wherein the step of generating video bitstream further comprising a step of incorporating a first flag at a sequence level to indicate whether slice boundaries are LCU-aligned or non-LCU aligned.

3. The method of claim 1, wherein the step of generating video bitstream further comprising a step of incorporating a first flag at a sequence level to indicate whether an end_of_slice_flag is used for context-based adaptive binary arithmetic coding (CABAC).

4. The method of claim 1, wherein the step of generating video bitstream further comprising a step of incorporating first information at a sequence level, wherein the first information indicates minimum CU size required for leaf coding units (CUs) in the last LCU to incorporate an end_of_slice_flag, and wherein the end_of_slice_flag enables the slice to terminate at a last leaf CU in the last LCU by asserting the end_of_slice_flag in the last leaf CU in the last LCU.

5. The method of claim 1, wherein the step of generating slice layer bitstream further comprising:

incorporating first information at a sequence level, wherein the first information indicates minimum CU size required for a leaf CU in the last LCU to incorporate an end_of_slice_flag;

incorporating a first flag in each of the LCUs in the slice to indicate possibility of being the last LCU in the slice;

incorporating the end_of_slice_flag in the leaf CU of the last LCU indicated by the first flag if the leaf CU is same or larger than the minimum CU size for the end of slice; and

incorporating the end_of_slice_flag for sharing by the leaf CUs of the last LCU indicated by the first flag, wherein the leaf CUs sharing the end_of_slice_flag are within a block having the minimum CU size for the end of slice.

6. The method of claim 1, wherein the step of generating slice layer bitstream further comprising:

incorporating a first flag in each of the LCUs in the slice to indicate possibility of being the last LCU in the slice; and

incorporating an end_of_slice_flag in each leaf CU of the last LCU indicated by the first flag.

7. The method of claim 1, wherein the step of generating slice layer bitstream further comprising:

incorporating a first flag in each of the LCUs in the slice to indicate possibility of being the last LCU in the slice;

incorporating a SCU number count of smallest CUs in the last LCU and skipping an end_of_slice_flag for the last LCU indicated by the first flag; and

skipping the SCU number count and the end_of_slice_flag for LCUs other than the last LCU.

8. The method of claim 1, wherein the step of generating slice layer bitstream further comprising a step of incorporating an LCU number count for the LCUs in the slice to avoid a need for incorporating an end_of_slice_flag in each of the LCUs in the slice when the slice is LCU-aligned.

9. The method of claim 1, wherein the step of generating slice layer bitstream further comprising a step of incorporating an LCU number count for the LCUs in the slice, a second address associated with the last LCU in the slice, a SCU (smallest CU) number count for the SCUs in the last LCU when the slice is non-LCU-aligned.

10. The method of claim 1, wherein the step of generating slice layer bitstream further comprising a step of incorporating an LCU index for the first LCU of the slice, a second address associated with the first LCU in the slice, an SCU (smallest CU) index for a first SCU in the first LCU when the slice is non-LCU-aligned.

38. The method of claim 2, wherein the sequence level is a sequence parameter set (SPS) or a picture parameter set (PPS).

39. The method of claim 3, wherein the sequence level is a sequence parameter set (SPS) or a picture parameter set (PPS).

40. The method of claim 4, wherein the sequence level is a sequence parameter set (SPS) or a picture parameter set (PPS).

41. The method of claim 5, wherein the sequence level is a sequence parameter set (SPS) or a picture parameter set (PPS).

11. A method for video decoding, the method comprising:

receiving a video bitstream comprising a slice layer bitstream;

extracting an alignment flag from the video bitstream to determine whether a slice associated with the slice layer bitstream is largest coding unit (LCU) aligned or non-LCU-aligned, wherein the slice comprises a group of LCUs having a first LCU and a last LCU; and

decoding the slice layer bitstream to provide the slice, wherein said decoding the slice layer bitstream comprises a step of deriving slice structure information in the video bitstream to determine slice boundaries.

12. The method of claim 11, wherein the step of deriving slice structure information further comprising a step of extracting a first flag at a sequence level to determine whether an end_of_slice_flag is used for context-based adaptive binary arithmetic coding (CABAC).

13. The method of claim 11, wherein the step of deriving slice structure information further comprising a step of extracting first information at a sequence level to determine minimum CU size required for a leaf coding unit (CU) of the last LCU to incorporate an end_of_slice_flag, and wherein the end_of_slice_flag is used to determine slice termination according to a value of the end_of_slice_flag in the leaf CU of the last LCU.

14. The method of claim 11, wherein the step of deriving slice structure information further comprising:

extracting first information at a sequence level to determine minimum CU size required for a leaf CU in the last LCU to incorporate an end_of_slice_flag;

extracting a first flag in each of the group of LCUs to determine possibility of being the last LCU in the slice;

extracting the end_of_slice_flag in the leaf CU of the last LCU indicated by the first flag if the leaf CU is same or larger than the minimum CU size for the end of slice; and

extracting the end_of_slice_flag for the leaf CUs of the last LCU indicated by the first flag, wherein the leaf CUs within a block having the minimum CU size for the end of slice share the end_of_slice_flag.

15. The method of claim 11, wherein the step of deriving slice structure information further comprising:

extracting a first flag in each of the group of LCUs to determine possibility of being the last LCU in the slice; and

extracting an end_of_slice_flag in each leaf CU of the last LCU indicated by the first flag.

16. The method of claim 11, wherein the step of deriving slice structure information further comprising:

extracting a first flag in each of the group of LCUs to determine possibility of being the last LCU in the slice; and

extracting a SCU number count of smallest CUs in the last LCU indicated by the first flag to determine slice termination.

17. The method of claim 11, wherein the step of deriving slice structure information further comprising a step of extracting an LCU number count for the group of LCUs to determine slice termination.

18. The method of claim 11, wherein the step of deriving slice structure information further comprising a step of extracting an LCU number count for the group of LCUs, a second address associated with the last LCU in the slice, a SCU (smallest CU) number count for the SCUs in the last LCU when the slice is non-LCU-aligned to determine slice termination.

19. The method of claim 11, wherein the step of deriving slice structure information further comprising a step of extracting an LCU index for the first LCU of the slice, a second address associated with the first LCU in the slice, an SCU (smallest CU) index for first SCU in the first LCU when the slice is non-LCU-aligned to determine slice termination.

42. The method of claim 12, wherein the sequence level is a sequence parameter set (SPS) or a picture parameter set (PPS).

43. The method of claim 13, wherein the sequence level is a sequence parameter set (SPS) or a picture parameter set (PPS).

44. The method of claim 14, wherein the sequence level is a sequence parameter set (SPS) or a picture parameter set (PPS).

20. An apparatus for video coding, the apparatus comprising:

means for partitioning video input data into largest coding units (LCUs);

means for configuring a slice to include a plurality of LCUs, having a first LCU and a last LCU;

wherein the first LCU and the last LCU are selected from a group consisting of a fractional LCU and a whole LCU and wherein the fractional LCU is formed by partitioning the whole LCU into leaf CUs according to a quadtree;

a video encoder module to generate compressed video data for the slice;

means for generating a slice layer bitstream comprising the compressed video data for the slice; and

means for generating a video bitstream comprising the slice layer bitstream.

21. The apparatus of claim 20, wherein the means for generating a slice layer bitstream further comprising means for sending a first flag at a sequence level to indicate whether an end_of_slice_flag is used for context-based adaptive binary arithmetic coding.

22. The apparatus of claim 20, wherein the means for generating a slice layer bitstream further comprising means for sending first information at a sequence level to indicate minimum CU size required for a leaf coding unit (CU) of the last LCU to incorporate an end_of_slice_flag, and wherein the end_of_slice_flag is used to indicate slice termination according to a value of the end_of_slice_flag in the leaf CU of the last LCU.

23. The apparatus of claim 20, wherein the means for generating a slice layer bitstream further comprising:

means for sending first information at a sequence level to indicate minimum CU size required for a leaf coding unit (CU) in the last LCU to incorporate an end_of_slice_flag;

means for sending a first flag in each of the LCUs in the slice to indicate possibility of being the last LCU in the slice;

means for sending the end_of_slice_flag in the leaf CU of the last LCU indicated by the first flag if the leaf CU is same or larger than the minimum CU size for the end of slice; and

means for sending the end_of_slice_flag for the leaf CUs of the last LCU indicated by the first flag, wherein the leaf CUs within a block having the minimum CU size for the end of slice share the end_of_slice_flag.

24. The apparatus of claim 20, wherein the means for generating a slice layer bitstream further comprising:

means for sending a first flag in each of the LCUs in the slice to indicate possibility of being the last LCU in the slice; and

means for sending an end_of_slice_flag in each leaf CU of the last LCU indicated by the first flag.

25. The apparatus of claim 20, wherein the means for generating a slice layer bitstream further comprising:

means for sending a first flag in each of the LCUs in the slice to indicate possibility of being the last LCU in the slice; and

means for sending a SCU number count of smallest CUs in the last LCU indicated by the first flag to indicate slice termination.

26. The apparatus of claim 20, wherein the means for generating a slice layer bitstream further comprising means for sending an LCU number count for the LCUs in the slice to indicate slice termination.

27. The apparatus of claim 20, wherein the means for generating a slice layer bitstream further comprising means for sending an LCU number count for the LCUs in the slice, a second address associated with the last LCU in the slice, a SCU (smallest CU) number count for the SCUs in the last LCU when the slice is non-LCU-aligned to indicate slice termination.

28. The apparatus of claim 20, wherein the means for generating a slice layer bitstream further comprising means for sending an LCU index for the first LCU of the slice, a second address associated with the first LCU in the slice, an SCU (smallest CU) index for first SCU in the first LCU when the slice is non-LCU-aligned to indicate slice termination.

29. An apparatus for video decoding, the apparatus comprising:

means for receiving a video bitstream comprising a slice layer bitstream;

means for extracting an alignment flag from the video bitstream to determine whether a slice associated with the slice layer bitstream is largest coding unit (LCU) aligned or non-LCU-aligned, wherein the slice comprises a group of LCUs having a first LCU and a last LCU; and

a video decoder module to decode the slice layer bitstream into the slice, wherein the video decoder module comprises means for deriving slice structure information in the video bitstream to determine slice boundaries.

30. The apparatus of claim 29, wherein the means for deriving slice structure information further comprising means for extracting a first flag at a sequence level to determine whether an end_of_slice_flag is used for context-based adaptive binary arithmetic coding.

31. The apparatus of claim 29, wherein the means for deriving slice structure information further comprising means for extracting first information at a sequence level to determine minimum CU size required for a leaf coding unit (CU) of the last LCU to incorporate an end_of_slice_flag, and wherein the end_of_slice_flag is used to determine slice termination according to a value of the end_of_slice_flag in the leaf CU of the last LCU.

32. The apparatus of claim 29, wherein the means for deriving slice structure information further comprising:

means for extracting first information at a sequence level to determine minimum CU size required for a leaf coding unit (CU) in the last LCU to incorporate an end_of_slice_flag;

means for extracting a first flag in each of the group of LCUs to determine possibility of being the last LCU in the slice;

means for extracting the end_of_slice_flag in the leaf CU of the last LCU indicated by the first flag if the leaf CU is same or larger than the minimum CU size for the end of slice; and

means for extracting the end_of_slice_flag for the leaf CUs of the last LCU indicated by the first flag, wherein the leaf CUs within a block having the minimum CU size for the end of slice share the end_of_slice_flag.

33. The apparatus of claim 29, wherein the means for deriving slice structure information further comprising:

means for extracting a first flag in each of the group of LCUs to determine possibility of being the last LCU in the slice; and

means for extracting an end_of_slice_flag in each leaf CU of the last LCU indicated by the first flag.

34. The apparatus of claim 29, wherein the means for deriving slice structure information further comprising:

means for extracting a first flag in each of the group of LCUs to determine possibility of being the last LCU in the slice; and

means for extracting a SCU number count of smallest CUs in the last LCU indicated by the first flag to determine slice termination.

35. The apparatus of claim 29, wherein the means for deriving slice structure information further comprising means for extracting an LCU number count for the group of LCUs to determine slice termination.

36. The apparatus of claim 29, wherein the means for deriving slice structure information further comprising means for extracting an LCU number count for the group of LCUs, a second address associated with the last LCU in the slice, a SCU (smallest CU) number count for the SCUs in the last LCU when the slice is non-LCU-aligned to determine slice termination.

37. The apparatus of claim 29, wherein the means for deriving slice structure information further comprising means for extracting an LCU index for the first LCU of the slice, a second address associated with the first LCU in the slice, an SCU (smallest CU) index for a first SCU in the first LCU when the slice is non-LCU-aligned to determine slice termination.