Method or device for coding a sequence of source pictures

• US 20060013307A1
• Filed: 06/29/2005
• Published: 01/19/2006
• Est. Priority Date: 07/06/2004
• Status: Active Grant

• Current Assignee: InterDigital Madison Patent Holdings (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Hiron, Franck, Francois, Edouard, Olivier, Yannick
• Granted Patent: US 7,801,218 B2
• Time in Patent Office: Days
• US Class Current: 375/240.160
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/112 according to a given display mode, e.g. for interlaced or progressive display mode
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/194 involving only two passes
• CPC Class Codes: H04N 19/53 Multi-resolution motion estimation; Hierarchical motion estimation
• CPC Class Codes: H04N 19/537 Motion estimation other than block-based
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/85 using pre-processing or post-processing specially adapted for video compression

Abstract

The method is characterized in that the pre-analysis phase performs correlation level calculations of the even and odd field blocks of the current picture with the even and odd blocks of the current picture with the even and odd field blocks of the reference picture based on motion vectors calculated during this phase and corresponding to the blocks to impose, during the coding mode decision stage and among the inter coding modes, the inter coding between fields of the same parity or of opposing parity or the inter coding between frames, according to the correlation levels.

Claims

1. Method for coding a sequence of source pictures containing a pre-analysis phase with pel-recursive type motion estimation between the current picture and a reference picture, and an actual coding phase by picture blocks, with a block matching motion estimation stage between the current picture and the reference picture, followed by a coding mode decision stage such as the intra mode, the inter mode between fields of the same parity or opposing parity or between frames, wherein the pre-analysis phase performs correlation level calculations for the even and odd field blocks of the current picture with the even and odd field blocks of the reference picture based on the motion vectors calculated at this phase and corresponding to the blocks to impose, during the coding mode decision stage and among the inter coding modes, the inter coding between fields of the same parity or opposing parity or the inter coding between frames, according to correlation levels.

2. Method according to claim 1, wherein the inter coding between fields is imposed when the correlation level between fields of opposing parity is lower than the correlation level between fields of the same parity.

3. Method according to claim 1, wherein the pre-analysis phase also implements correlation calculations between a frame block of the current picture with a frame block of a reference picture to determine the coding mode between fields or between frames according to the correlation levels.

4. Method according to claim 1, wherein the correlation calculation consists in a calculation of the following DFD value:

$\mathrm{DFD}=\underset{i,j=0}{\overset{i,j=15}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br><br><br>{\mathrm{pix}}_c<br><br>\left(i,j\right)-{\mathrm{pix}}_{\mathrm{pred}}<br><br>\left(i,j\right)<br><br>$

pix_c(i,j) corresponding to the luminance value of one pixel of the line i and column j of a current block,

pix_pred(i, j) corresponding to the luminance value of a pixel of the line i and column j of a block designated by the motion vector in the reference picture or the predicted block

5. Method according to claim 1, wherein a picture block is partitioned into an upper block and a lower block, the upper block corresponding to the upper field and the lower block to the lower field, or vice versa, wherein the inter mode between fields consists of a choice of the reconstructed upper or lower field of the reference picture for each of the upper and lower blocks and wherein this choice depends on the correlation measurements on the entire picture block.

6. Method according to claim 1, wherein the pre-analysis phase contains a noise reduction phase by motion-compensated filtering based on the motion calculated by the pel-recursive type motion estimation.

7. Method according to claim 1, wherein the block matching motion estimator is of the hierarchical type.

8. Method according to claim 1, wherein the pel-recursive type motion estimation is implemented on a source picture of lower resolution.

9. Method according to claim 1, wherein the motion vectors calculated during the pre-analysis phase and corresponding to the blocks are those calculated for the pixels relative to the blocks.

10. Method according to claim 1, wherein the motion vectors calculated during the pre-analysis phase and corresponding to the blocks are obtained from the median value or the average value of the motion vector components calculated for the pixels relating to the blocks.

11. Method according to claim 1, wherein the correlation calculations are performed on several reference pictures and wherein the pre-analysis phase implements a selection of one reference picture or pictures according to the correlation values.

12. Coding device for the implementation of the method of claim 1, containing a pre-analysis circuit with a pel-recursive type motion estimator and an actual coding circuit by picture blocks containing a picture block matching motion estimator connected to a coding mode decision circuit, wherein the pre-analysis circuit performs correlation calculations of the even and odd field blocks of the current picture with the even and odd field blocks of the reference picture based on the motion vectors calculated by the pel-recursive type motion estimator to impose on the coding mode decision circuit and among the inter coding modes, the inter coding between fields of the same parity or opposing parity or the inter coding between frames, according to correlation levels.

13. Device according to claim 12, wherein the pre-analysis circuit transmits coding mode information to the block matching motion estimation circuit to define a motion estimation on the fields and/or the frame relative to the reconstructed picture.