Method for coefficient bitdepth limitation, encoder and bitstream generation apparatus

• US 20060227867A1
• Filed: 04/12/2005
• Published: 10/12/2006
• Est. Priority Date: 04/12/2005
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Winger, Lowell L., Cote, Guy
• Granted Patent: US 7,949,044 B2
• Time in Patent Office: Days
• US Class Current: 375/240.30
• CPC Class Codes: H04N 19/103 Selection of coding mode or of prediction mode
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A method for coefficient bitdepth limitation in an encoder and/or bitstream generation apparatus including the steps of (A) generating one or more residual block coefficients in response to a video signal and one or more coding parameters and (B) manipulating the one or more coding parameters such that the one or more residual block coefficients are prevented from having values greater than a bitdepth of the video signal plus a predefined number of bits.

Claims

1. A method for coefficient bitdepth limitation comprising the steps of:

generating one or more residual block coefficients in response to a video signal and one or more coding parameters; and

manipulating said one or more coding parameters, wherein said one or more residual block coefficients are prevented from having values greater than a bitdepth of said video signal plus a predefined number of bits.

2. The method according to claim 1, wherein (i) said video signal has a profile selected from the group consisting of 8-bit High Profile, 10-bit High 10 profile, 10-bit High 422 profile and 12-bit High 444 profile and (ii) said predefined number of bits comprises eight bits.

3. The method according to claim 1, wherein said one or more coding parameters comprise one or more parameters selected from the group consisting of quantization parameter (qP), weightscale, bitrate, quality, encode-duration and macroblock mode.

4. The method according to claim 1, wherein said one or more residual block coefficients further comprise one or more coefficients selected from the group consisting of 4×

4, 4×

4 luma DC, 4×

4 chroma DC and 8×

8 residual blocks.

5. The method according to claim 1, wherein a weighting matrix coefficient is set to a value greater than or equal to a predetermined minimum value determined when a quantization parameter (qP) is set equal to zero.

6. The method according to claim 1, wherein a weighting matrix coefficient is set to a value greater than or equal to a predetermined minimum value determined when a quantization parameter (qP) is set to a value greater than or equal to two.

7. The method according to claim 1, wherein a quantization parameter (qP) is set to a value substantially equal to a minimum value for a predetermined weighting matrix coefficient.

8. The method according to claim 1, wherein said coding parameters are configured to clip said residual block coefficients.

9. The method according to claim 1, wherein said coding parameters are manipulated to select a prediction mode that does not cause an overflow.

10. An encoder apparatus comprising:

means for generating one or more residual block coefficients in response to a video signal and one or more coding parameters; and

means for manipulating said one or more coding parameters, wherein said one or more residual block coefficients are prevented from having values greater than a bitdepth of said video signal plus a predefined number of bits.

11. An encoder apparatus comprising:

an encoding circuit configured to generate one or more residual block coefficients in response to a video signal and one or more coding parameters; and

a control circuit configured to manipulate said one or more coding parameters, wherein said one or more residual block coefficients are limited to values less than or equal to a bitdepth of said video signal plus a predefined number of bits.

12. The encoder apparatus according to claim 11, wherein said encoding circuit comprises:

a coefficient forming circuit configured to generate said one or more residual block coefficients in response to one or more residual coefficients; and

a coding decision circuit configured to generate said residual coefficients in response to said video signal and said one or more coding parameters.

13. The encoder apparatus according to claim 11, wherein (i) said video signal has a profile selected from the group consisting of 8-bit High Profile, 10-bit High 10 profile, 10-bit High 422 profile and 12-bit High 444 profile and (ii) said predefined number of bits comprises eight bits.

14. The encoder apparatus according to claim 11, wherein said one or more coding parameters comprise one or more parameters selected from the group consisting of quantization parameter (qP), weightscale, bitrate, quality, encode-duration and macroblock mode.

15. The encoder apparatus according to claim 11, wherein said one or more residual block coefficients further comprise one or more coefficients selected from the group consisting of 4×

4, 4×

4 luma DC, 4×

4 chroma DC and 8×

8 residual blocks.

16. The encoder apparatus according to claim 11, wherein said control circuit is configured to set a weighting matrix coefficient to a value greater than or equal to a predetermined minimum value determined when a quantization parameter (qP) is equal to zero.

17. The encoder apparatus according to claim 11, wherein said control circuit is configured (i) to set a weighting matrix coefficient to a value greater than or equal to a predetermined minimum value determined when a quantization parameter (qP) is set to a value greater than or equal to two.

18. The encoder apparatus according to claim 11, wherein said control circuit is configured to set a quantization parameter (qP) to a value substantially equal to a minimum value for a predetermined weighting matrix coefficient.

19. The encoder apparatus according to claim 11, wherein said control circuit is configured to clip said residual block coefficients.

20. The encoder apparatus according to claim 11, wherein said control circuit is configured to select a prediction mode that does not cause an overflow.