Using order value for processing a video picture

• US 7,292,636 B2
• Filed: 03/02/2004
• Issued: 11/06/2007
• Est. Priority Date: 07/15/2002
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Haskell, Barin Geoffry, Dumitras, Adriana, Singer, David William, Puri, Atul
• Primary Examiner(s): An; Shawn S.
• Application Number:
  US10/792,669
• Publication Number:
  US 20040240557A1
• Time in Patent Office: 1,344 Days
• Field of Search: 375/240.23, 375/240.16, 375/240.12, 375/240.26, 375/240.01, 382/238, 382/246, 382/235, 382/245
• US Class Current: 375/240.23
• CPC Class Codes: G06T 9/005 Statistical coding, e.g. Huffman, run length coding
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• 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 19/43 Hardware specially adapted for motion estimation or compensation
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• 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 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/513 Processing of motion vectors
• CPC Class Codes: H04N 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
• CPC Class Codes: H04N 19/587 involving temporal sub-sampling or interpolation, e.g. decimation or subsequent interpolation of pictures in a video sequence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083

Abstract

A method and apparatus for variable accuracy inter-picture timing specification for digital video encoding is disclosed. Specifically, the present invention discloses a system that allows the relative timing of nearby video pictures to be encoded in a very efficient manner. In one embodiment, the display time difference between a current video picture and a nearby video picture is determined. The display time difference is then encoded into a digital representation of the video picture. In a preferred embodiment, the nearby video picture is the most recently transmitted stored picture. For coding efficiency, the display time difference may be encoded using a variable length coding system or arithmetic coding. In an alternate embodiment, the display time difference is encoded as a power of two to reduce the number of bits transmitted.

Claims

1. For a bitstream comprising a first video picture, a second video picture, and a third video picture, a method of decoding comprising:

computing a particular value that is based on (i) a first order difference value between an order value for the third video picture and an order value for the first video picture, and (ii) a second order difference value between an order value for the second video picture and the order value for the first video picture;

computing a particular motion vector for the second video picture based on the particular value and a motion vector for the third video picture; and

decoding at least one video picture by using the computed motion vector.

2. The method of claim 1, wherein an order value for a particular video picture is for specifying a position for the particular video picture in a sequence of video pictures.

3. The method of claim 2, wherein the sequence is a sequence for displaying the video pictures.

4. The method of claim 1, wherein an order value for a particular video picture is representative of a positional relationship of the particular video picture with respect to another video picture.

5. The method of claim 1, wherein the particular value is proportional to the second order difference value.

6. The method of claim 1, wherein the particular value is inversely proportional to the first order difference value.

7. The method of claim 1, wherein the order value for the second video picture is derived from a value stored in a slice header that is associated with the second video picture.

8. The method of claim 1, wherein the second video picture is decoded by using the computed motion vector.

9. The method of claim 8, wherein the first and third video pictures are decoded before the second video picture.

10. A computer readable medium storing a computer program for decoding at least one video picture from a set comprising a first video picture, a second video picture, and a third video picture, the computer program executable by at least one processor, the computer program comprising sets of instructions for:

computing a particular value that is based on (i) a first order difference value between an order value for the third video picture and an order value for the first video picture, and (ii) a second order difference value between an order value for the second video picture and the order value for the first video picture;

computing a particular motion vector for the second video picture based on the particular value and a motion vector for the third video picture; and

decoding at least one video picture by using the computed motion vector.

11. The computer readable medium of claim 10, wherein an order value for a particular video picture is for specifying a position for the particular video picture in a sequence of video pictures.

12. The computer readable medium of claim 11, wherein the sequence is a sequence for displaying the video pictures.

13. The computer readable medium of claim 10, wherein an order value for a particular video picture is representative of a positional relationship of the particular video picture with respect to another video picture.

14. The computer readable medium of claim 10, wherein the particular value is proportional to the second order difference value.

15. The computer readable medium of claim 10, wherein the particular value is inversely proportional to the first order difference value.

16. The computer readable medium of claim 10, wherein the order value for the second video picture is derived from a value stored in a slice header that is associated with the second video picture.

17. The computer readable medium of claim 10, wherein the second video picture is decoded by using the computed motion vector.

18. The computer readable medium of claim 17, wherein the first and third video pictures are decoded before the second video picture.