Video compression

• US 6,285,716 B1
• Filed: 12/16/1996
• Issued: 09/04/2001
• Est. Priority Date: 06/17/1994
• Status: Expired due to Term

• Current Assignee: British Broadcasting Corporation, Snell & Wilcox Limited
• Original Assignee: British Broadcasting Corporation, Snell & Wilcox Limited
• Inventors: Knee, Michael James, Wells, Nicholas Dominic, Devlin, Bruce Fairbairn
• Primary Examiner(s): Britton, Howard
• Application Number:
  US08/767,448
• Time in Patent Office: 1,723 Days
• Field of Search: 375/240, 375/240.28, 348/17, 348/423, 348/845, 348/423.1
• US Class Current: 375/240.28
• CPC Class Codes: H04N 19/142 Detection of scene cut or scene change
• CPC Class Codes: H04N 19/179 the unit being a scene or a shot
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/39 involving multiple description coding [MDC], i.e. with separate layers being structured as independently decodable descriptions of input picture data
• 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 19/42 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 19/46 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 19/87 involving scene cut or scene change detection in combination with video compression

Abstract

An MPEG-2 or other compressed video stream (CP) can be manipulated as separate information bus (IB) and coefficient (CP*) streams. The information bus stream (IB) contains motion vector information but also information derived from a previous decoding operation (14, 18) for use in a subsequent coding operation (22). Processing in the coefficient domain enables bit rate conversion without decoding to the pixel level and also simplifies the combination of MPEG layers.

Claims

1. A signal transmission chain comprising at least one video compression coder adapted to receive a digital video signal and to generate therefrom a compressed or partially compressed coded signal utilising motion compensation based on macroblocks of a picture, and at least one compression decoder adapted to receive a compressed or partially compressed coded signal and to generate therefrom a decoded or partially decoded signal, characterised in that an information bus extends from a decoder or to a coder in the chain, the information bus including a picture rate timing and a macroblock rate timing and carrying both picture rate and macroblock rate information relating to a coding operation for use in a later signal process.

2. A signal transmission chain according to claim 1, wherein the information bus extends from a decoder to a later coder in the chain.

3. A signal transmission chain according to claim 2, wherein the information bus carries information relating to a decoding process in said decoder for use in an encoding process in said coder.

4. A signal transmission chain according to claim 1 wherein the information bus carries motion vector information together with at least one piece of information selected from the group consisting of macroblock scan mode;

error concealment flag;

causes for concealment;

numbers of bits used per block; and

candidate motion vectors.

5. A signal transmission chain according to claim 1 wherein the information bus carries motion vector information together with at least one piece of information selected from the group consisting of motion vector source;

cut detection;

numbers of I, P and B frames remaining in GOP;

film phase (or 3;

2 pulldown) detection;

field or frame like index;

pan vector identification; and

letterbox detection.

6. A signal transmission chain according to claim 1, wherein the picture rate information carried by the information bus comprises coding type and quantiser matrix information.

7. A signal transmission chain according to claim 6, wherein the picture rate information carried by the information bus further comprises time reference and display offsets information.

8. A signal transmission chain according to claim 6, wherein the picture rate information further includes at least one piece of information selected from the group consisting of motion vector source;

cut detection;

numbers of I, P and B frames remaining in GOP;

film phase (or 3;

2 pulldown) detection;

field or frame like index;

pan vector identification; and

letterbox detection.

9. A signal transmission chain according to claim 1, wherein the macroblock rate information carried by the information bus comprises macroblock type, and motion vector information.

10. A signal transmission chain according to claim 9, wherein the macroblock rate information carried by the information bus further comprises motion type and motion vector type information.

11. A signal transmission chain according to claim 9, wherein the macroblock rate information carried by the information bus further includes at least one piece of information selected from the group consisting of macroblock scan mode;

error concealment flag;

causes for concealment;

numbers of bits used per block; and

candidate motion vectors.

12. A signal transmission chain comprising at least one video compression coder adapted to receive a digital video signal and to generate therefrom a compressed or partially compressed coded signal utilising motion compensation based on macroblocks of a picture, and at least one compression decoder adapted to receive a compressed or partially compressed coded signal and to generate therefrom a decoded or partially decoded signal, characterised in that an information bus extends from a decoder or to a coder in the chain, the information bus including a picture rate timing and a macroblock rate timing and carrying both picture rate and macroblock rate information relating to a coding operation for use in a later signal process, the picture rate information comprising coding type and quantiser matrix information and the macroblock rate information comprising macroblock type and motion vector information.