Method of predicting motion and texture data

1. Method, as part of a scalable encoding or decoding method, for generating for at least one block of pixels of a picture of a high resolution sequence of high resolution interlaced pictures at least one motion predictor from motion data associated with the pictures of a low resolution sequence of low resolution interlaced pictures each interlaced picture comprising a top field interlaced with a bottom field and able to be coded in frame mode or in field mode, each field of an interlaced picture having associated with it a temporal reference, wherein the method comprises

generating said at least one motion predictor from the motion data associated with at least one block of pixels of the top field of a low resolution picture of the same temporal reference as the top field of said high resolution picture when said low resolution picture is coded in field mode;

generating said at least one motion predictor from the motion data associated with at least one block of pixels of the bottom field of said low resolution picture of the same temporal reference as the bottom field of said high resolution picture when said low resolution picture is coded in field mode; and

generating said at least one motion predictor from the motion data associated with at least one block of pixels of a low resolution picture comprising a field with the same temporal reference as the top field or bottom field of the high resolution picture when said low resolution picture is coded in frame mode.

2. Method according to claim 1 , wherein generating said at least one motion predictor for said at least one block of pixels of said high resolution picture comprises subsampling said motion data associated with said at least one block of pixels of said top field of a low resolution picture of the same temporal reference as the top field of said high resolution picture with a horizontal inter-layer ratio in the horizontal direction of the picture and a vertical inter-layer ratio in the vertical direction of the picture.

3. Method according to claim 1 , wherein generating said at least one motion predictor for said at least one block of pixels of said high resolution picture comprises subsampling said motion data associated with said at least one block of pixels of said bottom field of said low resolution picture of the same temporal reference as the bottom field of said high resolution picture with a horizontal inter-layer ratio in the horizontal direction of the picture and a vertical inter-layer ratio in the vertical direction of the picture.

4. Method according to claim 1 , wherein generating said at least one motion predictor for said at least one block of pixels of said high resolution picture comprises subsampling said motion data associated with said at least one block of pixels of said low resolution picture comprising a field with the same temporal reference as the top field or bottom field of the high resolution picture with a horizontal inter-layer ratio in the horizontal direction of the picture and a vertical inter-layer ratio in the vertical direction of the picture.

5. Method according to claim 1 , wherein the method further comprises, for said block of pixels of said high resolution picture:

generating at least one texture predictor from the texture data associated with at least one block of pixels of the top field of a low resolution picture of the same temporal reference as the top field of said high resolution picture; and/or

generating at least one texture predictor from the texture data associated with at least one block of pixels of the bottom field of a low resolution picture of the same temporal reference as the bottom field of said high resolution picture; and/or

generating at least one texture predictor from the texture data associated with at least one block of pixels of each of said top and bottom fields of said low resolution picture.

6. Method according to claim 1 , wherein the motion data associated with the low resolution pictures comprises motion vectors.

7. Method according to claim 6 , wherein the motion vectors associated with a low resolution picture coded in frame mode or with each of the top and bottom fields of a low resolution picture coded in field mode have the same parity.

8. Method according to claim 7 wherein the low resolution pictures are encoded according to the MPEG-4 AVC standard.