Methods and Systems for Entropy Coder Initialization

• US 20120082218A1
• Filed: 10/01/2010
• Published: 04/05/2012
• Est. Priority Date: 10/01/2010
• Status: Active Grant

• Current Assignee: Velos Media, LLC (Inception Holdings, LLC)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Misra, Kiran, Segall, Christopher A.
• Granted Patent: US 9,313,514 B2
• Time in Patent Office: Days
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/124 Quantisation
• 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 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• 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 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/197 including determination of the initial value of an encoding parameter H04N19/56 takes precedence
• CPC Class Codes: H04N 19/436 using parallelised computational arrangements
• 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 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

Aspects of the present invention are related to systems and methods for initialization of entropy encoders and decoders.

Claims

1. A method for decoding a video frame in a video sequence, said method comprising:

in a video decoder, receiving an entropy slice;

identifying a slice-start elementary unit in said entropy slice; and

initializing, to a slice default scan order, an adaptive scan calculation associated with entropy decoding said slice-start elementary unit.

2. The method as described in claim 1, wherein said slice-start elementary unit is a macroblock.

3. The method as described in claim 1 further comprising:

identifying a row-start elementary unit in said entropy slice; and

initializing, to a row default scan order, an adaptive scan calculation associated with entropy decoding said row-start elementary unit.

4. The method as described in claim 3, wherein said row-start elementary unit is a macroblock.

5. A method for decoding a video frame in a video sequence, said method comprising:

in a video decoder, receiving an entropy slice;

identifying a slice-start elementary unit in said entropy slice; and

initializing, to a first coefficient scan order in a plurality of coefficient scan orders, a coefficient scan order associated with entropy decoding said slice-start elementary unit.

6. The method as described in claim 5, wherein said slice-start elementary unit is a macroblock.

7. The method as described in claim 5, wherein said first coefficient scan order is signaled in a bitstream associated with said video sequence.

8. The method as described in claim 7, wherein said first coefficient scan order is signaled by a method selected from the group consisting of signaled as normative syntax and signaled as a non-normative message.

9. A method for decoding a video frame in a video sequence, said method comprising:

in a video decoder, receiving an entropy slice;

identifying a row-start elementary unit in said entropy slice; and

initializing, to a first coefficient scan order in a plurality of coefficient scan orders, a coefficient scan order associated with entropy decoding said row-start elementary unit.

10. The method as described in claim 9, wherein said row-start elementary unit is a macroblock.

11. The method as described in claim 9, wherein said first coefficient scan order is signaled in a bitstream associated with said video sequence.

12. The method as described in claim 11, wherein said first coefficient scan order is signaled by a method selected from the group consisting of signaled as normative syntax and signaled as a non-normative message.

13. A method for decoding a video frame in a video sequence, said method comprising:

in a video decoder, receiving an entropy slice;

identifying an elementary unit in said entropy slice;

fetching a first context according to a predefined context fetch order; and

entropy decoding a first coefficient in said elementary unit using said first context.

14. The method as described in claim 13, wherein said elementary unit is a macroblock.

15. The method as described in claim 13 further comprising storing said entropy decoded first coefficient.

16. The method as described in claim 15 further comprising reordering a plurality of said stored entropy decoded coefficients according to an adaptive scanning order.

17. The method as described in claim 13 further comprising:

fetching a next context according to said predefined context fetch order, wherein said next context is immediately subsequent to said first context in said predefined context fetch order; and

entropy decoding a second coefficient in said elementary unit using said second context, wherein said second coefficient is immediately subsequent to said first coefficient in a bitstream.

18. The method as described in claim 17 further comprising:

storing said entropy decoded first coefficient; and

storing said entropy decoded second coefficient.

19. The method as described in claim 18 further comprising reordering a plurality of said stored entropy decoded coefficients according to an adaptive scanning order.

20. A method for encoding a video frame of a video sequence, said method comprising:

in an encoder, fetching a first transform coefficient;

fetching a first context according to a predefined context fetch order; and

entropy encoding said first transform coefficient using said first context.

21. The method as described in claim 20 further comprising:

fetching a second transform coefficient;

fetching a next context according to said predefined context fetch order, wherein said next context is immediately subsequent to said first context in said predefined context fetch order; and

entropy encoding said second transform coefficient using said second context.

22. The method as described in claim 21, wherein said first transform coefficient is stored according to a scanning order.

23. The method as described in claim 20, wherein said first transform coefficient is stored according to a scanning order.

24. A method for decoding a video frame in a video sequence, said method comprising:

in a video decoder, receiving an entropy slice;

identifying said entropy slice is a forward-predicted B-slice; and

initializing, using a P-slice method, a context associated with said entropy slice.

25. The method as described in claim 24, wherein said identifying comprises receiving in a bitstream associated with said entropy slice a flag value indicating said entropy slice is a forward-predicted B-slice.

26. The method as described in claim 24, wherein said identifying comprises comparing a first picture list with a second picture list.

27. A method for decoding a video frame in a video sequence, said method comprising:

in a video decoder, identifying a slice-start elementary unit in said entropy slice;

estimating a number of processed bins associated with an entropy coder; and

when said estimated number of processed bins meets a first criterion, initializing a context state associated with entropy decoding said slice-start elementary unit to a first value; and

when said estimated number of processed bins does not meet said first criterion, initializing said context state associated with entropy decoding said slice-start elementary unit adaptively based on a quantization parameter.

28. The method as described in claim 27, wherein said meeting said first criterion comprises said estimated number of processed bins being greater than a threshold.

29. A method for decoding a video frame in a video sequence, said method comprising:

in a video decoder, receiving an entropy slice;

identifying a slice-start elementary unit in said entropy slice; and

initializing, to a first scanning order associated with a previously decoded elementary unit, a second scanning order associated with entropy decoding said slice-start elementary unit.

30. The method as described in claim 29, wherein said slice-start elementary unit is a macroblock.

31. A method for decoding a video frame in a video sequence, said method comprising:

in a video decoder, receiving an entropy slice;

identifying a row-start elementary unit in said entropy slice; and

initializing, to a first scanning order associated with a previously decoded elementary unit, a second scanning order associated with entropy decoding said row-start elementary unit.

32. The method as described in claim 31, wherein said row-start elementary unit is a macroblock.