Video compression using multiple computing agents

• US 6,008,848 A
• Filed: 06/11/1997
• Issued: 12/28/1999
• Est. Priority Date: 04/06/1995
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Viscito, Eric, Tiwari, Prasoon
• Primary Examiner(s): LEE, RICHARD J
• Application Number:
  US08/873,201
• Time in Patent Office: 930 Days
• Field of Search: 348/420, 348/419, 348/405, 348/384, 348/390, 348/400-402, 348/407, 348/409-413, 348/415, 348/699, 348/416
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/114 Adapting the group of pictures [GOP] structure, e.g. number of B-frames between two anchor frames H04N19/107 takes precedence
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/142 Detection of scene cut or scene change
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/177 the unit being a group of pictures [GOP]
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/436 using parallelised computational arrangements
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A system and method of using multiple processors to perform video compression is provided. A video sequence is partitioned into subsequences and processing assignments for the subsequences are distributed among a plurality of processors. A picture type is then determined for each picture in each subsequence and the encoding complexity of each picture is modeled, based on the picture type. Based on the modeling, a number of bits is allocated to each picture. Each picture is then compressed in accordance with the bits allocated. Another aspect provides for encoding of pictures in a video sequence using dynamic modeling of the encoding complexity of future pictures in the video sequence. Bits are allocated to the encoding of a current picture in the video sequence based on the dynamic model. The current picture is then encoded based on the bits allocated.

Claims

1. A method of encoding pictures in a video sequence comprising:

a) establishing a bit budget of Z bits for a present subsequence of the frames of the video sequence;

b) preliminarily distributing the Z bits among the frames of the present subsequence so as to provide uniform picture quality throughout the present subsequence;

c) determining whether the number of bits in frame v violates MPEG VBV restrictions regarding buffering allowable bits per picture for said video sequence; and

d) redefining the subsequence as containing frames O to V and repeating steps b) and c) when the number of bits in frame V violates said restrictions.

2. The method of claim 1 wherein establishing the bit budget includes:

e) set w equal to the bit rate of the subsequence times the display time of a field of the present subsequence; and

f) set Z equal to w times the number of fields.

3. The method of claim 1 further comprising, when there is no violation of said restrictions, the steps of:

ascertaining if there are additional frames remaining to be encoded;

defining a successive subsequence for said additional frames remaining to be encoded; and

repeating said establishing a bit budget, preliminarily distributing, determining and redefining for said successive subsequence.

4. A method of encoding pictures in a video sequence comprising the steps of:

dynamically modeling an encoding complexity of future pictures in the video sequence;

establishing a present subsequence of pictures including the future pictures, past pictures and the present picture;

establishing a bit budget of Z bits for the present subsequence of the pictures of the video sequence;

allocating bits to the encoding of a current picture in the video sequence based on the modeling by preliminarily distributing the Z bits among the pictures of the present subsequence so as to provide uniform picture quality throughout the present subsequence;

determining whether the number of bits distributed through the present picture violates MPEG VBV restrictions regarding buffering allowable bits per picture for said video sequence;

redefining the present subsequence as containing frames 0 to the present picture and repeating said preliminarily distributing and said determining steps when the present picture violates said restrictions; and

encoding the current picture based on the bits allocated.

5. The method of claim 4 wherein establishing the bit budget includes:

set w equal to the bit rate of the subsequence times the display time of a field of the present subsequence; and

set Z equal to w tines the number of fields.

6. The method of claim 4 further comprising, when there is no violation of said restrictions, the steps of:

ascertaining if there are additional frames remaining to be encoded;

defining a successive subsequence for said additional frames remaining to be encoded; and

repeating said establishing a bit budget, preliminarily distributing, determining and redefining for said successive subsequence.