Method and/or apparatus for reducing the complexity of non-reference frame encoding using selective reconstruction

• US 7,324,595 B2
• Filed: 09/22/2003
• Issued: 01/29/2008
• Est. Priority Date: 09/22/2003
• Status: Expired due to Fees

• 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.
• Primary Examiner(s): PHILIPPE, GIMS S
• Application Number:
  US10/667,948
• Publication Number:
  US 20050063465A1
• Time in Patent Office: 1,590 Days
• Field of Search: 375/240.12, 375/240.13, 375/240.16, 375/240.15, 375/240.03, 375/240.24, 382/238
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/58 Motion compensation with long-term prediction, i.e. the reference frame for a current frame not being the temporally closest one H04N19/23 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

A method for implementing non-reference frame prediction in video compression comprising the steps of (A) setting a prediction flag (i) “off” if non-reference frames are used for block prediction and (ii) “on” if non-reference frames are not used for block prediction, (B) if the 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 the prediction flag is on, bypassing the inverse quantization step and the inverse transform step.

Claims

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

(A) setting a prediction flag (i) off if non-reference frames are used for block prediction and (ii) on if non-reference 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, generating said output video signal while 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 non-reference frame macroblock encoding when non-reference 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 non-reference frame processing; and

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

16. The method according to claim 1, wherein said prediction flag is generated in response to inter motion compensation processing.

17. The method according to claim 1, wherein said prediction flag is generated in response to intra prediction compensation processing.

18. The method according to claim 1, wherein said prediction flag is generated in response to (i) intra prediction compensation processing and (ii) inter motion compensation processing.

19. The method according to claim 1, wherein said prediction flag is implemented as a register bit set during encoding.

20. The method according to claim 19, wherein said register bit is included in an intermediate signal used to generate said output video signal.

14. An apparatus for implementing non-reference frame prediction in video compression comprising:

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

means for 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, if said prediction flag is off; and

means for bypassing said inverse quantization step and said inverse transform step, if said prediction flag is on.

15. The apparatus according to claim 14, wherein said output data stream comprises an H.264 compliant bitstream.