Methods and systems for scalable-to-non-scalable bit-stream rewriting

• US 8,767,834 B2
• Filed: 01/24/2008
• Issued: 07/01/2014
• Est. Priority Date: 03/09/2007
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Segall, Christopher A., Zhao, Jie
• Primary Examiner(s): Vu, Huy D
• Assistant Examiner(s): LAMONT, BENJAMIN S
• Application Number:
  US12/019,127
• Publication Number:
  US 20080219354A1
• Time in Patent Office: 2,350 Days
• Field of Search: 375/240.23
• US Class Current: 375/240.23
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 19/60 using transform coding

Abstract

Aspects of the present invention relate to systems and methods for selectively determining a quantization parameter based on coding parameters. In some embodiments, a quantization parameter selection may be based on the presence of non-zero transform coefficients as well as other parameters. Some embodiments relate to rewriting a multi-layer bitstream to a single-layer bitstream with a quantization parameter selected with reference to transform coefficients. Some embodiments convert a scalable, multi-layer video sequence into a single-layer, non-scalable video sequence that is compatible with legacy devices.

Claims

1. A method for image bitstream processing, said method comprising:

extracting symbols from a multi-layer image bitstream, said symbols being related to an image portion;

generating combined transform coefficients from said symbols, wherein said combined transform coefficients are a combination of enhancement layer coefficients and base layer coefficients;

determining whether said combined transform coefficients comprise any non-zero coefficients;

when said combined transform coefficients comprise a non-zero coefficient, using a quantization parameter identified in said symbols for processing said image portion; and

when said combined transform coefficients do not comprise a non-zero coefficient, using a default quantization parameter, wherein said default quantization parameter is a quantization parameter used for a previous image portion, for processing said image portion.

2. A method as described in claim 1 wherein said processing said image portion comprises in-loop filtering.

3. A method as described in claim 1 wherein said processing said image portion comprises signaling a quantization offset parameter for a subsequent image portion.

4. A method as described in claim 1 further comprising scaling said base layer coefficients and combining said scaled base layer coefficients with said enhancement layer coefficients to form said combined transform coefficients.

5. A method as described in claim 1 wherein said image portion is an image block.

6. A method as described in claim 1 further comprising storing the quantization parameter selected for said processing as a default quantization parameter for a next image portion.

7. A method as described in claim 1 wherein said processing comprises storing said combined transform coefficients in a second bitstream.

8. A method as described in claim 1 further comprising determining image intensity values based on said combined transform coefficients and filtering said image intensity values.

9. A method for combining a bitstream base layer with a bitstream enhancement layer in a multi-layer bitstream, said method comprising:

a) generating base-layer transform coefficients from said multi-layer bitstream;

b) generating enhancement-layer residual coefficients from said multi-layer bitstream;

c) combining said base-layer coefficients with said enhancement-layer residual coefficients to produce combined-layer coefficients;

d) determining whether said combined-layer coefficients comprise any non-zero coefficients;

e) when said combined-layer coefficients comprise a non-zero coefficient, encoding said combined-layer with a quantization parameter and signaling said quantization parameter with a quantization parameter identifier; and

f) when said combined-layer coefficients do not comprise a non-zero coefficient, encoding said combined-layer with a default quantization parameter from a previous block.

10. A method as described in claim 9 further comprising scaling said base-layer transform coefficients.

11. A method as described in claim 9 further comprising using said quantization parameter or said default quantization parameter for in-loop filtering for a current portion of said bitstream.

12. A method as described in claim 9 further comprising using said quantization parameter or said default quantization parameter for signaling a quantization offset parameter for a subsequent bitstream portion.

13. A method as described in claim 10 wherein said scaling is based on quantization parameters of said base layer and said enhancement layer.

14. A method as described in claim 9 further comprising entropy coding said combined layer coefficients.

15. A method as described in claim 9 wherein said base layer and said enhancement layer are part of an SVC-compliant bitstream and said combined layer is part of an AVC-compliant bitstream.