Chroma motion vector derivation

• US 20050053294A1
• Filed: 09/02/2004
• Published: 03/10/2005
• Est. Priority Date: 09/07/2003
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Hsu, Pohsiang, Mukerjee, Kunal
• Granted Patent: US 7,352,905 B2
• Time in Patent Office: Days
• US Class Current: 382/236
• CPC Class Codes: H04N 19/102 characterised by the element, parameter or selection affected or controlled by the adaptive coding
• CPC Class Codes: H04N 19/109 among a plurality of temporal predictive coding modes
• CPC Class Codes: H04N 19/11 among a plurality of spatial predictive coding modes
• CPC Class Codes: H04N 19/112 according to a given display mode, e.g. for interlaced or progressive display mode
• 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 19/129 Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]
• 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 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/16 for a given display mode, e.g. for interlaced or progressive display mode
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• 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 19/463 by compressing encoding parameters before transmission
• CPC Class Codes: H04N 19/51 : Motion estimation or motion compensation
• CPC Class Codes: H04N 19/52 : by predictive encoding
• CPC Class Codes: H04N 19/523 : with sub-pixel accuracy
• CPC Class Codes: H04N 19/593 : involving spatial prediction techniques
• CPC Class Codes: H04N 19/61 : in combination with predictive coding
• CPC Class Codes: H04N 19/63 : using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/70 : characterised by syntax aspects related to video coding, e.g. related to compression standards
• 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
• CPC Class Codes: H04N 19/93 : Run-length coding

Abstract

A decoder receives luma motion vector information for plural luma motion vectors for a macroblock (e.g., a 4:2:0 macroblock). The decoder derives a chroma motion vector for each of the plural luma motion vectors by performing at least one calculation on the luma motion vector information, maintaining a 1:1 ratio of chroma motion vectors to luma motion vectors for the macroblock. For example, the decoder receives four luma (frame or field) motion vectors for a macroblock and derives four chroma motion vectors for the macroblock. The deriving can comprise sub-sampling and/or rounding (e.g., using a field-based rounding table).

Claims

1. A method comprising:

receiving luma motion vector information for more than two luma motion vectors for one macroblock, each of the more than two luma motion vectors associated with at least part of the macroblock; and

deriving a chroma motion vector associated with at least part of the macroblock for each of the more than two luma motion vectors, the deriving comprising performing at least one calculation involving a rounding table on the luma motion vector information.

2. The method of claim 1 wherein the macroblock is a field-coded macroblock.

3. The method of claim 1 wherein the macroblock is a field-coded macroblock having four luma field motion vectors, each of the four luma field motion vectors describing motion in part of a luma field of the macroblock.

4. The method of claim 3 wherein each chroma motion vector is a chroma field motion vector describing motion in a different part of a chroma field of the macroblock.

5. The method of claim 1 wherein the rounding table is a field-based rounding table, and wherein the deriving comprises rounding at least a portion of the luma motion vector information using the field-based rounding table.

6. The method of claim 1 wherein the macroblock is a frame-coded macroblock having four luma frame motion vectors, each of the four luma frame motion vectors associated with a different luma block of the macroblock.

7. The method of claim 1 wherein the macroblock is a 4:

2;

0 macroblock.

8. The method of claim 1 wherein the deriving comprises rounding and sub-sampling at least a portion of the luma motion vector information.

9. The method of claim 8 wherein the rounding table is a field-based rounding lookup table, and wherein the rounding is performed using the field-based rounding lookup table.

10. The method of claim 1 wherein the more than two luma motion vectors are in quarter-pixel units.

11. A computer-readable medium having computer-executable instructions stored thereon for performing the method of claim 1.

12. In a video decoder, a method comprising:

receiving luma motion vector information for one or more luma motion vectors, each of the one or more luma motion vectors associated with at least part of a macroblock in an interlaced P-frame; and

deriving a chroma motion vector associated with at least part of the macroblock for each of the one or more luma motion vectors, the deriving based at least in part on the motion vector information for the one or more luma motion vectors;

wherein the video decoder is operable to decode macroblocks predicted using four luma field motion vectors in an interlaced P-frame.

13. The method of claim 12 wherein the decoder is further operable to decode inter-coded macroblocks having four luma frame motion vectors, inter-coded macroblocks having two luma field motion vectors, inter-coded macroblocks having one luma frame motion vector, and intra macroblocks.

14. The method of claim 12 wherein the deriving comprises deriving four chroma field motion vectors.

15. The method of claim 12 wherein the deriving comprises applying a field-based rounding lookup table to at least a portion of the luma motion vector information.

16. A computer-readable medium comprising computer-executable instructions for causing a computer to perform a method comprising:

receiving luma motion vector information for one or more luma field motion vectors, each of the one or more luma field motion vectors associated with at least part of a macroblock in an interlaced frame coded picture; and

deriving a chroma motion vector associated with at least part of the macroblock for each of the one or more luma field motion vectors, the deriving based at least in part on the motion vector information for the one or more luma field motion vectors, the deriving the chroma motion vector comprising;

rounding a luma field motion vector component using a field-based rounding table; and

sub-sampling the luma field motion vector component.

17. The method of claim 16 wherein the interlaced frame coded picture is an interlaced P-frame.

18. The method of claim 16 wherein the field-based rounding table is an integer array consisting of the following set of values:

{0, 0, 1, 2, 4, 4, 5, 6, 2, 2, 3, 8, 6, 6, 7, 12}.

19. The method of claim 16 wherein the one or more luma field motion vectors comprises four luma field motion vectors

20. The method of claim 16 wherein the macroblock is a 4:

2;

0 macroblock, and wherein the sub-sampling comprises dividing the luma field motion vector component by two.