Sample array coding for low-delay

Patent metadata

Field	Value
Publication number	US-9866857-B2
Application number	US-201715639259-A
Country	US
Kind code	B2
Filing date	Jun 30, 2017
Priority date	Jul 15, 2011
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

The entropy coding of a current part of a predetermined entropy slice is based on, not only, the respective probability estimations of the predetermined entropy slice as adapted using the previously coded part of the predetermined entropy slice, but also probability estimations as used in the entropy coding of a spatially neighboring, in entropy slice order preceding entropy slice at a neighboring part thereof. Thereby, the probability estimations used in entropy coding are adapted to the actual symbol statistics more closely, thereby lowering the coding efficiency decrease normally caused by lower-delay concepts. Temporal interrelationships are exploited additionally or alternatively.

First claim

What is claimed:

1. A decoder for reconstructing a sample array from an entropy-encoded data stream encoded with a video, the decoder comprising:
an entropy decoder configured to entropy decode a plurality of slice subsets in the entropy-encoded data stream so as to reconstruct different portions of the sample array, each of the plurality of slice subsets comprising entropy-encoded data for a corresponding portion of the sample array, and the different portions forming rows of blocks of the sample array,
wherein the entropy decoder is configured to, with respect to each of the plurality of slice subsets, perform entropy decoding along a respective entropy coding path using a first probability estimation, at least by:
initializing the first probability estimation before decoding a first block of a first row corresponding to the slice subset based on a second probability estimation of a second block of a second row, the second row spatially-neighboring the first row and corresponding to a preceding slice subset, wherein entropy decoding of the preceding slice subset begins before the entropy decoding of the slice subset, and
storing the second probability estimation after the second block is entropy-decoded, wherein the entropy decoder is configured to use the stored second probability estimation for initializing the first probability estimation.

2. The decoder according to claim 1 , wherein the entropy decoder is configured to entropy-decode the plurality of slice subsets in a slice subset order, the slice subset order is chosen such that, along the slice subset order, the different portions follow each other in a direction angled relative to the entropy coding paths of the slice subsets.

3. The decoder according to claim 1 , wherein the entropy decoder is configured to adapt the first probability estimation along the entropy coding path using a previously-decoded part of the slice subset.

4. The decoder according to claim 1 , wherein the entropy decoder is configured to, in entropy decoding a current part of the slice subset, adapt the first probability estimation based on a third probability estimation of a portion of the second row, the portion of the second row spatially-neighboring a portion of the first row corresponding to the current part of the slice subset.

5. The decoder according to claim 4 , wherein the entropy decoder is configured to adapt the first probability estimation based on an average of the first probability estimation adapted using the previously-decoded part of the slice subset and the third probability estimation.

6. The decoder according to claim 2 , wherein the entropy decoder is configured to steer the entropy decoding of immediately consecutive slice subsets in the slice subset order so that a distance of currently decoded blocks of portions corresponding to the immediately consecutive slice subsets measured in blocks along the entropy coding paths is prevented from becoming lower than two blocks.

7. The decoder according to claim 2 , wherein the entropy decoder is configured to steer the entropy decoding of immediately consecutive slice subsets in the slice subset order so that a distance of currently decoded blocks of portions corresponding to the immediately consecutive slice subsets measured in blocks along the entropy coding paths remains two blocks.

8. The decoder according to claim 1 , wherein the slice subsets are sub-divided into chunks, and the decoder further comprises a de-interleaver to de-interleave the chunks and the entropy decoder is configured to start the entropy decoding of the slice subsets in parallel along the entropy coding paths even before a reception of any of the slice subsets as a whole.

9. The decoder according to claim 1 , wherein the sample array is a current sample array of a sequence of sample arrays and the entropy decoder is configured to entropy-decode a slice subset based on the first probability estimation as adapted using the second probability estimation, the previously-decoded part of the slice subset, and a fourth probability estimation used in entropy decoding a previously decoded frame of the entropy-encoded data stream relating to one of the sample arrays other than the current sample array.

10. The decoder according to claim 1 , wherein the decoder is at least a portion of a programmable logic device, programmable gate array, microprocessor, computer or hardware apparatus.

11. A method for reconstructing a sample array from an entropy-encoded data stream encoded with a video, the method comprising:
entropy decoding a plurality of slice subsets in the entropy-encoded data stream so as to reconstruct different portions of the sample array, each of the plurality of slice subsets comprising entropy-encoded data for a corresponding portion of the sample array, and the different portions forming rows of blocks of the sample array, the entropy decoding comprising, with respect to each of the plurality of slice subsets:
entropy decoding along a respective entropy coding path using a first probability estimation, including:
initializing the first probability estimation before decoding a first block of a first row corresponding to the slice subset based on a second probability estimation of a second block of a second row, the second row spatially-neighboring the first row and corresponding to a preceding slice subset, wherein entropy decoding of the preceding slice subset begins before the entropy decoding of the slice subset, and
storing the second probability estimation after the second block is entropy-decoded, wherein the stored second probability estimation is used for initializing the first probability estimation.

12. The method according to claim 11 , wherein the entropy decoding of the plurality of slice subsets is performed in a slice subset order, the slice subset order is chosen such that, along the slice subset order, the different portions follow each other in a direction angled relative to the entropy coding paths of the slice subsets.

13. The method according to claim 11 , further comprising adapting the first probability estimation along the entropy coding path using a previously-decoded part of the slice subset.

14. The method according to claim 11 , further comprising, for entropy decoding a current part of the slice subset, adapting the first probability estimation based on a third probability estimation of a portion of the second row, the portion of the second row spatially-neighboring a portion of the first row corresponding to the current part of the slice subset.

15. The method according to claim 14 , wherein the adapting comprises adapting the first probability estimation based on an average of the first probability estimation adapted using the previously-decoded part of the slice subset and the third probability estimation.

16. The method according to claim 12 , further comprising steering the entropy decoding of immediately consecutive slice subsets in the slice subset order so that a distance of currently decoded blocks of portions corresponding to the immediately consecutive slice subsets measured in blocks along the entropy coding paths is prevented from becoming lower than two blocks.

17. The method according to claim 12 , further comprising steering the entropy decoding of immediately consecutive slice subsets in the slice subset order so that a distance of currently decoded blocks of portions corresponding to the immediately consecutive slice subsets measured in blocks along the entropy coding paths remains two blocks.

18. The method according to claim 11 , wherein the sl

Assignees

• Ge Video Compression Llc

Inventors

• George Valeri
• Henkel Anastasia
• Kirchhoffer Heiner
• Marpe Detlev
• Schierl Thomas

Classifications

• H03M7/3071 Primary

  Prediction · CPC title

• H04N19/91

  Entropy coding, e.g. variable length coding [VLC] or arithmetic coding · CPC title

• H04N19/13 Primary

  Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC] · CPC title

• H04N19/503

  involving temporal prediction (adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109) · CPC title

• H03M7/4037

  Prefix coding · CPC title