Method and/or apparatus for reducing the complexity of H.264 B-frame encoding using selective reconstruction

• US 20040240549A1
• Filed: 05/30/2003
• Published: 12/02/2004
• Est. Priority Date: 05/30/2003
• 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, Novotny, Pavel, Gallant, Michael D.
• Granted Patent: US 7,310,371 B2
• Time in Patent Office: Days
• US Class Current: 375/240.15
• CPC Class Codes: H04N 19/103 Selection of coding mode or of prediction mode
• CPC Class Codes: H04N 19/11 among a plurality of spatial predictive coding modes
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• 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 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

An apparatus comprising an output circuit, a first processing circuit and a second processing circuit. The output circuit may be configured to generate an output data stream in response to (i) a first intermediate signal, (ii) a second intermediate signal, and (iii) a third intermediate signal. The first processing circuit may be configured to generate the first intermediate signal in response to (i) a processed video signal and (ii) a prediction flag. The second processing circuit may be configured to generate (i) the processed video signal, (ii) the second intermediate signal and (iii) the third intermediate signal in response to an input video signal.

Claims

1. A method for implementing B-frame prediction in video compression comprising the steps of:

(A) setting a prediction flag (i) off if B-frames are used for block prediction and (ii) on if B-frames are not used for block prediction;

(B) if said prediction flag is off, generating an output video signal in response to an input video signal by performing an inverse quantization step and an inverse transform step in accordance with a predefined coding specification; and

(C) if said prediction flag is on, bypassing said inverse quantization step and said inverse transform step.

2. The method according to claim 1, wherein said input video signal comprises a series of macroblocks.

3. The method according to claim 2, wherein said method operates (i) in a first mode if said prediction flag is on and (ii) a second mode if said prediction flag is off.

4. The method according to claim 3, wherein (i) said first mode comprises an intra prediction mode and (ii) said second mode comprises an inter prediction mode.

5. The method according to claim 4, wherein said inter prediction mode uses information from a previous one of said macroblocks to encode a subsequent one of said macroblocks.

6. The method according to claim 2, further comprising the steps of:

generating an array configured to store which of said modes was used to encode each of said macroblocks; and

if said mode information is needed to encode a macroblock, reconstructing the mode used macroblock from the array information.

7. The method according to claim 1, wherein said method reduces complexity on B-frame macroblock encoding when B-frames are not used for prediction.

8. The method according to claim 1, wherein said output video signal comprises an H.264 compliant encoded bitstream.

9. The method according to claim 1, further comprising the step of:

reconstructing an I-frame macroblock if said prediction flag is on.

10. The method according to claim 9, further comprising the step of:

skipping said reconstruction step if said prediction flag is off.

11. The method according to claim 1, wherein said prediction flag comprises a constrained intra prediction (CIPF) flag.

12. The method according to claim 1, wherein said method

(i) executes a deblocking filtering stage when in a first mode and

(ii) skips said deblocking filtering stage when in a second mode.

13. The method according to claim 1, further comprising the step of:

(D) forcing a decoder to not use intra macroblocks in B-frame processing; and

skipping step (A) when step (D) is implemented.

14. An apparatus comprising:

an output circuit configured to generate an output data stream in response to (i) a first intermediate signal, (ii) a second intermediate signal, and (iii) a third intermediate signal;

a first processing circuit configured to generate said first intermediate signal in response to (i) a processed video signal and (ii) a prediction flag; and

a second processing circuit configured to generate (i) said processed video signal, (ii) said second intermediate signal and (iii) said third intermediate signal in response to an input video signal.

15. The apparatus according to claim 14, wherein said second processing circuit is configured to generate said processed video signal, said first intermediate signal, and said second intermediate signal in further response to a fourth intermediate signal.

16. The apparatus according to claim 15, wherein said first processing circuit is configured to generate said fourth intermediate signal.

17. The apparatus according to claim 15, wherein said fourth intermediate signal comprises (i) said first intermediate signal when in a first mode and (ii) a processed version of said fourth intermediate signal when in a second mode.

18. The apparatus according to claim 17, wherein said first and second modes are selected in response to said prediction flag.

19. The apparatus according to claim 15, wherein said first and second processing circuits are configured to respond to one or more control signals generated by a control circuit.

20. The apparatus according to claim 15, wherein said output data stream comprises an H.264 compliant bitstream.

21. An apparatus comprising:

means for generating an output data stream in response to (i) a first intermediate signal, (ii) a second intermediate signal, and (iii) a third intermediate signal;

means for generating said first intermediate signal in response to (i) a processed video signal and (ii) a prediction flag; and

means for generating (i) said processed video signal, (ii) said second intermediate signal and (iii) said third intermediate signal in response to an input video signal.

22. The apparatus according to claim 21, wherein said means for generating said processed video signal, said first intermediate signal, and said second intermediate signal further respond to a fourth intermediate signal.