Intra estimation chroma mode 0 sub-block dependent prediction

• US 7,646,815 B2
• Filed: 07/15/2003
• Issued: 01/12/2010
• Est. Priority Date: 07/15/2003
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Booth, Simon, Dattani, Doni S., Winger, Lowell L.
• Primary Examiner(s): Dastouri; Mehrdad
• Assistant Examiner(s): HALLENBECK-HUBER, JEREMIAH CHARLES
• Application Number:
  US10/619,531
• Publication Number:
  US 20050013375A1
• Time in Patent Office: 2,373 Days
• Field of Search: 375/240.24, 375/240.12
• US Class Current: 375/240.24
• CPC Class Codes: H04N 11/044 involving transform coding
• 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 19/136 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 19/186 the unit being a colour or a chrominance component

Abstract

An apparatus comprising a first processing circuit and a second processing circuit. The first processing circuit may be configured to generate a plurality of reconstructed samples in response to one or more macroblocks of an input signal. The second processing circuit may be configured to determine a best intra prediction chroma mode 0 predictor for reach chroma sub-block of a current macroblock in response to available reconstructed samples adjacent to the current macroblock.

Claims

1. An apparatus comprising:

A first processing circuit configured to generate a plurality of reconstructed samples in response to a plurality of neighboring macroblocks of an input signal; and

A second processing circuit configured to;

determine an intra prediction chroma mode 0 from a plurality of intra prediction chroma modes;

generate a plurality of sum values S0, S1, S2 and S3 based on said reconstructed samples for a current chroma block said sum values being used in a plurality of formulas; and

determine a plurality of intra prediction chroma mode 0 predictions A, B, C and D for said current chroma block

wherein in a first case when only said sum value S0 is unavailable, said intra prediction chroma mode 0 predictors are generated using the formulas A=(S2+2)/4, B=(S1+2)/4, C=(S3+2)/4 and D=(S1+S3+4)/8.

2. The apparatus according to claim 1,

wherein said second processing circuit is implemented in a decoding loop of an encoder.

3. The apparatus according to claim 1, wherein:

said first and second processing circuits are part of a decoder; and

said second processing circuit is further configured to use a subset of said formulas to generate said intra prediction chroma mode 0 predictors of said current chroma block, said formulas in said subset being identified in a signal received within a compressed and encoded video bitstream.

4. The apparatus according to claim 1, wherein said apparatus comprises an H.264 compliant decoder.

5. The apparatus according to claim 1, wherein said second processing circuit comprises:

a third processing circuit configured to generate said current chroma block in response to said intra prediction chroma mode 0 predictors.

6. The apparatus according to claim 5, wherein said second processing circuit further comprises:

a control circuit configured to generate said intra prediction chroma mode 0 predictor for each of said chroma sub-blocks in response to said reconstructed samples.

7. The apparatus according to claim 6, wherein said control circuit is further configured to determine a position of a top edge and a left edge of a chroma block of said current macroblock in a current slice.

8. The apparatus according to claim 7, wherein said reconstructed samples comprise a plurality of reconstructed samples in a row adjacent to said top edge of said chroma block.

9. The apparatus according to claim 7, wherein said reconstructed samples further comprise a plurality of reconstructed samples in a column adjacent to said left edge of said chroma block.

10. The apparatus according to claim 1, wherein in a second case when only said sum value S0 is available, said intra prediction chroma mode 0 predictors are generated using the formulas A=(S0+2)/4, B is set to a predetermined constant, C=(S0+2)/4, and D is set to said predetermined constant.

11. The apparatus according to claim 1, wherein said second processing circuit is further configured to generate a signal that identifies a subset of said formulas used by said second circuit to generate said intra prediction chroma mode 0 predictors correspond to said current chroma block, said apparatus further comprising an encoder configured to generate a compressed and encoded video bit stream incorporating said signal.

12. An apparatus comprising:

means for generating a plurality of reconstructed samples in response to a plurality of neighboring macroblocks of an input signal; and

means for;

determining an intra prediction chroma mode 0 from a plurality of intra prediction chroma modes, generating a plurality of sum values S0, S1, S2 and S3 based on said reconstructed samples for a current chroma block said sum values being used in a plurality of formulas; and

determining a plurality of intra prediction chroma mode 0 predictions A, B, C and D for said current chroma block

wherein in a first case when only said sum value S0 is unavailable, said intra prediction chroma mode 0 predictors are generated using the formulas A=(S2+2)/4, B=(S1+2)/4, C=(S3+2)/4 and D=(S1+S3+4)/8.

13. A method for intra prediction of a chroma block comprising the steps of:

generating a plurality of reconstructed samples in response to a plurality of neighboring macroblocks of an input signal using a first processing circuit;

determining an intra prediction chroma mode 0 from a plurality of intra prediction chroma modes;

generating a plurality of sum values S0, S1, S2 and S3 based on said reconstructed samples for a current chroma block said sum values being used in a plurality of formulas; and

determining a plurality of intra prediction chroma mode 0 predictions A, B, C and D for said current chroma block

wherein in a first case when only said sum value S0 is unavailable, said intra prediction chroma mode 0 predictors are generated using the formulas A=(S2+2)/4, B=(S1+2)/4, C=(S3+2)/4 and D=(S1+S3+4)/8.

14. The method according to claim 13, wherein each of said formulas used to generate each of said intra prediction chroma mode 0 predictors is selected independently in response to availability of said reconstructed samples adjacent to said chroma block.

15. The method according to claim 13, further comprising:

generating said reconstructed samples by inverse quantizing and inverse transforming a compressed bitstream.

16. The method according to claim 13, wherein each of said intra prediction chroma mode 0 predictors comprises a weighted average of one or more of said sum values.

17. The method according to claim 13, wherein in a second case when only said sum value S0 is available, said intra prediction chroma mode 0 predictors are generated using the formulas A=(S0+2)/4, B is set to a predetermined constant, C=(S0+2)/4, and D is set to said predetermined constant.

18. The method according to claim 17, wherein in a third case when only said sum value S1 unavailable said intra prediction chroma mode 0 predictors are generated using the formulas A=(S0+S2+4)/8, B=(S2+2)/4, C=(S3+2)/4 and D=(S3+2)/4.

19. The method according to claim 17, wherein said predetermined constant comprises a median chroma value.

20. The method according to claim 13 further comprising the steps of:

generating a signal that identifies a subset of said formulas used by a second processing circuit to generate said intra prediction chroma mode—

predictors corresponding to said first case; and

generating a compressed and encoded bitstream that incorporates said signal.

21. The method according to claim 13, wherein said first processing circuit is part of a decoder and said intra prediction chroma mode 0 predictors for said first case are generated using a subset of said formulas, said formulas in said subset being identified in a signal received within a compressed and encoded video bit stream.