Adaptation of scan order entropy coding

• US 10,356,411 B2
• Filed: 05/30/2017
• Issued: 07/16/2019
• Est. Priority Date: 05/30/2017
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google LLC (Alphabet Inc.)
• Inventors: He, Dake
• Primary Examiner(s): Saltarelli, Dominic D
• Application Number:
  US15/608,008
• Publication Number:
  US 20180352230A1
• Time in Patent Office: 777 Days
• Field of Search: 37524024, 37524025
• CPC Class Codes: H04N 19/129 Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

Systems and methods are disclosed for adapting scan order for entropy coding. For example, methods may include partitioning a block of video data into a plurality of groups of elements; decoding, using an entropy decoder, data from an encoded bitstream to obtain, using a first scan order, elements of a first group from the plurality of groups of elements; determining, based on the elements of the first group, a second scan order for a second group from the plurality of groups of elements; and decoding, using the entropy decoder, data from the encoded bitstream to obtain, using the second scan order, elements of the second group from the plurality of groups of elements.

Claims

1. A system for decoding video, comprising:

a memory; and

a processor, wherein the memory stores instructions executable by the processor to cause the system to;

partition a block of video data into a plurality of groups of elements;

decode, using an entropy decoder, data from an encoded bitstream to obtain, using a first scan order, elements of a first group from the plurality of groups of elements;

determine, based on the elements of the first group, a second scan order for a second group from the plurality of groups of elements; and

decode, using the entropy decoder, data from the encoded bitstream to obtain, using the second scan order, elements of the second group from the plurality of groups of elements.

2. The system of claim 1, wherein the elements of the block are quantized transform coefficients.

3. The system of claim 1, wherein the first group includes elements of a first row of the block and elements of a first column of the block.

4. The system of claim 3, wherein the instructions for determining, based on the elements of the first group, the second scan order for the second group include instructions executable by the processor to cause the system to:

determine a first count of non-zero elements in a portion of the first row of the block;

determine a second count of non-zero elements in a portion of the first column of the block; and

responsive to the first count being zero and the second count being positive, determining the second scan order to be a vertical scan order.

5. The system of claim 3, wherein the instructions for determining, based on the elements of the first group, the second scan order for the second group include instructions executable by the processor to cause the system to:

determine a first sum of magnitudes of elements in a portion of the first row of the block;

determine a second sum of magnitudes of elements in a portion of the first column of the block; and

responsive to the first sum being positive and the second sum being zero, determining the second scan order to be a horizontal scan order.

6. The system of claim 1, wherein the second group includes all remaining elements of the block outside of the first group.

7. The system of claim 1, wherein the second group includes elements of a first row and a first column of remaining elements of the block outside of the first group.

8. The system of claim 1, wherein the memory stores instructions executable by the processor to cause the system to:

determine, based on the decoded elements of the block, a category, wherein the category is one of horizontal, vertical, and other;

determine a context based on the category; and

decode, using an entropy decoder with the context, data from the encoded bitstream to obtain an intra-prediction mode for the block.

9. The system of claim 1, wherein the elements of the block each represent a sub-block of quantized transform coefficients.

10. A method for decoding video comprising:

partitioning a block of video data into a plurality of groups of elements;

decoding, using an entropy decoder, data from an encoded bitstream to obtain, using a first scan order, elements of a first group from the plurality of groups of elements;

determining, based on the elements of the first group, a second scan order for a second group from the plurality of groups of elements; and

decoding, using the entropy decoder, data from the encoded bitstream to obtain, using the second scan order, elements of the second group from the plurality of groups of elements.

11. The method of claim 10, wherein the elements of the block are quantized transform coefficients, and further comprising:

displaying video that is generated based in part on the decoded elements of the block.

12. A system for encoding video, comprising:

a memory; and

a processor, wherein the memory stores instructions executable by the processor to cause the system to;

partition a block of video data into a plurality of groups of elements;

encode, using an entropy encoder using a first scan order, elements of a first group from the plurality of groups of elements;

determine, based on the elements of the first group, a second scan order for a second group from the plurality of groups of elements; and

encode, using the entropy encoder using the second scan order, elements of the second group from the plurality of groups of elements.

13. The system of claim 12, wherein the elements of the block are quantized transform coefficients.

14. The system of claim 12, wherein the first group includes elements of a first row of the block and elements of a first column of the block.

15. The system of claim 14, wherein the instructions for determining, based on the elements of the first group, the second scan order for the second group include instructions executable by the processor to cause the system to:

determine a first count of non-zero elements in a portion of the first row of the block;

determine a second count of non-zero elements in a portion of the first column of the block; and

responsive to the first count being zero and the second count being positive, determining the second scan order to be a vertical scan order.

16. The system of claim 14, wherein the instructions for determining, based on the elements of the first group, the second scan order for the second group include instructions executable by the processor to cause the system to:

determine a first sum of magnitudes of elements in a portion of the first row of the block;

determine a second sum of magnitudes of elements in a portion of the first column of the block; and

responsive to the first sum being positive and the second sum being zero, determining the second scan order to be a horizontal scan order.

17. The system of claim 12, wherein the second group includes all remaining elements of the block outside of the first group.

18. The system of claim 12, wherein the second group includes elements of a first row and a first column of remaining elements of the block outside of the first group.

19. The system of claim 12, wherein the memory stores instructions executable by the processor to cause the system to:

determine, based on the elements of the block, a category, wherein the category is one of horizontal, vertical, and other;

determine a context based on the category; and

encode, using an entropy decoder with the context, an intra-prediction mode for the block.

20. The system of claim 12, wherein the elements of the block are based on a result of inter-frame prediction.