Method for deriving motion for high resolution pictures from motion data of low resolution pictures and coding and decoding devices implementing said method

Patent metadata

Field	Value
Publication number	US-9167266-B2
Application number	US-30915907-A
Country	US
Kind code	B2
Filing date	Jul 2, 2007
Priority date	Jul 12, 2006
Publication date	Oct 20, 2015
Grant date	Oct 20, 2015

Abstract

The invention relates to a method for deriving motion data for a macroblock divided in elementary blocks of a high resolution picture, called high layer macroblock, from motion data of macroblocks of a low resolution picture, called base layer macroblock. The method comprises the following steps:
computing, for each elementary block, an intermediate position within the low resolution picture from the elementary block position depending on the coding modes of the high layer macroblock and of the high and low resolution pictures; identifying the base layer macroblock, called base_MB, comprising the pixel located at the intermediate position; computing a final position within the low resolution picture from the virtual base layer position depending on the coding modes of the base_MB, of the high layer macroblock; identifying the base layer macroblock, called real_base_MB, comprising the pixel located at the final position; and deriving motion data, for the high layer macroblock, from motion data of the identified real_base_MB.

First claim

The invention claimed is:

1. Method, as part of a coding or decoding process, for deriving motion data for at least one high layer macroblock, divided into non-overlapping elementary blocks, of a high resolution picture from motion data associated with base layer macroblocks of a low resolution picture, whatever the format of said high and low resolution pictures is, a macroblock coding mode among frame mode and field mode being associated with each macroblock and a picture coding mode among field picture mode and frame picture mode being associated with said high resolution picture and with said low resolution picture, said method comprising:
computing, for each elementary block of said at least one macroblock, an intermediate position within said low resolution picture from said elementary block position within said high resolution picture depending on the coding mode of said high layer macroblock and depending on the picture coding modes of said high and low resolution pictures;
identifying, for each elementary block, the base layer macroblock, called base macroblock, comprising the pixel located at said intermediate position;
computing, for each elementary block, a final position within said low resolution picture, called real base layer position, from said intermediate position depending on the coding modes of said base macroblock and high layer macroblocks;
identifying, for each elementary block of said at least one macroblock, the base layer macroblock, called real base macroblock, comprising the pixel located at said real base layer position; and
deriving motion data, for said high layer macroblock, from motion data of said real base macroblock for each elementary block.

2. Method according to claim 1 , wherein base layer macroblocks are partitioned and motion data is associated with each of the partitions and wherein said method further comprises identifying, for each elementary block, the partition of said real base macroblock comprising the pixel located at said real base layer position after identifying, for each elementary block, the base layer macroblock, called real base macroblock, comprising the pixel located at said real base layer position.

3. Method according to claim 2 , wherein deriving motion data for said high layer macroblock comprises:
partitioning said high layer macroblock depending on said real base macroblock and on said identified partitioning of said real base macroblock for each elementary block; and
deriving motion vectors for each partition of said high layer macroblock from motion data of said real base macroblock for each elementary block.

4. Method according to claim 1 , wherein said high layer macroblock is a block of 16 by 16 pixels and wherein each elementary block is a block of 4 by 4 pixels.

5. Device for coding a sequence of high resolution pictures and a sequence of low resolution pictures whatever the format of said high and low resolution pictures is, each picture being divided in non overlapping macroblocks divided into non-overlapping elementary blocks, a macroblock coding mode among frame mode and field mode being associated with each macroblock and a picture coding mode among field picture mode and frame picture mode being associated with said high resolution pictures and with said low resolution pictures, said device comprising:
a first coding module configured to code said low resolution pictures, said first coding module generating motion data for macroblocks of said low resolution pictures and a base layer data stream;
inheritance module configured to derive motion data for at least one macroblock of a high resolution picture, called high layer macroblock from motion data of macroblocks a low resolution picture, called base layer macroblocks; and
a second coding module configured to code said high resolution pictures using said derived motion data, said second coding module generating an enhancement layer data stream;

wherein the inheritance module is configured to:
compute, for each elementary block of said at least one macroblock, an intermediate position within said low resolution picture from said elementary block position within said high resolution picture depending on the coding mode of said high layer macroblock and depending on the picture coding modes of said high and low resolution pictures;
identify, for each elementary block, the base layer macroblock, called base macroblock, comprising the pixel located at said intermediate position;
compute, for each elementary block, a final position within said low resolution picture, called real base layer position, from said intermediate position depending on the coding modes of said base macroblock and high layer macroblocks;
identify, for each elementary block of said at least one macroblock, the base layer macroblock, called real base macroblock, comprising the pixel located at said real base layer position; and
derive motion data, for said high layer macroblock, from motion data of said real base macroblock for each elementary block.

6. Device according to claim 5 , wherein said first coding module is an MPEG-4 AVC video encoder.

7. Device according to claim 5 , wherein said device further comprises a multiplexer configured to combine base layer data stream and enhancement layer data stream into a single data stream.

8. Device for decoding at least a sequence of high resolution pictures from low resolution pictures whatever the format of said high and low resolution pictures is, the coded pictures arising in the form of a data stream, each picture being divided in non overlapping macroblocks divided into non-overlapping elementary blocks, a macroblock coding mode among frame mode and field mode being associated with each macroblock and a picture coding mode among field picture mode and frame picture mode being associated with said high resolution pictures and with said low resolution pictures, said device comprising:
a first decoding module configured to decode at least a first part of said data stream in order to generate said low resolution pictures and motion data for macroblocks of said low resolution picture;
inheritance module configured to derive motion data for at least one macroblock of a high resolution picture, called high layer macroblock, from motion data of macroblocks of a low resolution picture, called base layer macroblocks; and
a second decoding module configured to decode at least a second part of said data stream using said derived motion data in order to generate high resolution pictures;

wherein the inheritance module is configured to:
compute, for each elementary block of said at least one macroblock, an intermediate position within said low resolution picture from said elementary block position within said high resolution picture depending on the coding mode of said high layer macroblock and depending on the picture coding modes of said high and low resolution pictures;
identify, for each elementary block, the base layer macroblock, called base macroblock, comprising the pixel located at said intermediate position;
compute, for each elementary block, a final position within said low resolution picture, called real base layer position, from said intermediate position depending on the coding modes of said base macroblock and high layer macroblocks;
identify, for each elementary block of said at least one macroblock, the base layer macroblock, called real base macroblock, comprising the pixel located at said real base layer position; and
derive motion data, for said high layer macroblock, from motion data of said real base macroblock for each elementary block.

9. Device according to claim 8 , wherein said first decoding module is an MPEG-4 AVC video decoder.

Assignees

• Francois Edouard
• Bottreau Vincent
• Vieron Jéróme
• Chevance Christophe
• Thomson Licensing

Inventors

• Francois Edouard
• Bottreau Vincent
• Vieron Jéróme
• Chevance Christophe

Classifications

• H04N19/517

  by encoding · CPC title

• H04N19/59 Primary

  involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution · CPC title

• H04N19/33

  in the spatial domain · CPC title

• H04N19/112

  according to a given display mode, e.g. for interlaced or progressive display mode · CPC title

• H04N19/16

  for a given display mode, e.g. for interlaced or progressive display mode · CPC title