Coding and decoding methods of a picture block, corresponding devices and data stream

1. A decoding method comprising:

while inter-layer prediction is enabled, reconstructing a second layer reference picture from a first layer reference picture of a decoder picture buffer of a scalable multi-layered stream and from data decoded from a second layer of the scalable multi-layered stream and storing the reconstructed second layer reference picture in the decoder picture buffer, wherein the reconstructed second layer reference picture is indicated as not to be displayed;

decoding a flag indicating that a subsequently decoded picture of the second layer is not using any inter-layer prediction, wherein inter-layer prediction is disabled after decoding the flag; and

reconstructing a picture block of the subsequently decoded picture at least from the reconstructed second layer reference picture.

2. The decoding method according to claim 1 , wherein the data decoded from the second layer are representative of a pixel-by-pixel difference between the second layer reference picture and the first layer reference picture.

3. The decoding method according to claim 1 , wherein the first layer is a base layer.

4. The decoding method of claim 1 , further comprising decoding from the second layer information for identifying the first layer reference picture.

5. The decoding method of claim 1 , wherein the second layer reference picture and the first layer reference picture are temporally aligned.

6. The decoding method according to claim 1 , wherein a part of the second layer is configured to be decoded using information from the first layer.

7. An encoding method comprising:

while inter-laver prediction is enabled, encoding in a second layer of a multi-layered stream a second layer reference picture of a decoder picture buffer from a first layer reference picture of the decoder picture buffer of the scalable multi-layered stream, wherein the second layer reference picture is indicated as not to be displayed;

encoding a flag indicating that a subsequently encoded picture of the second layer is not using any inter-layer prediction, wherein inter-layer prediction is disabled after decoding the flag; and

encoding a picture block of the subsequently encoded picture at least from the second layer reference picture.

8. The encoding method according to claim 7 , wherein encoding in the second layer the second layer reference picture comprises determining the pixel-by-pixel difference between the second layer reference picture and the first layer reference picture and encoding the pixel-by-pixel difference.

9. The encoding method according to claim 7 , wherein the first layer is a base layer.

10. The encoding method of claim 7 , further comprising encoding in the second layer information for identifying the first layer reference picture.

11. The encoding method of claim 7 , wherein the second layer reference picture and the first layer reference picture are temporally aligned.

12. A decoder comprising at least a processor configured to:

while inter-layer prediction is enabled, reconstruct a second layer reference picture from a first layer reference picture of a decoder picture buffer of a scalable multi-layered stream and from data decoded from a second layer of the scalable multi-layered stream and store the reconstructed second layer reference picture in the decoder picture buffer, wherein the reconstructed second layer reference picture is indicated as not to be displayed;

decode a flag indicating that a subsequently decoded picture of the second layer is not using any inter-layer prediction, wherein inter-layer prediction is disabled after decoding the flag; and

reconstruct a picture block of the subsequently decoded picture at least from the reconstructed second layer reference picture.

13. The decoder according to claim 12 , wherein the data decoded from the second layer are representative of a pixel-by-pixel difference between the second layer reference picture and the first layer reference picture.

14. The decoder according to claim 12 , wherein the first layer is a base layer.

15. The decoder according to claim 12 , wherein the at least one processor is further configured to decode from the second layer information for identifying the first layer reference picture.

16. The decoder according to claim 12 , wherein the second layer reference picture and the first layer reference picture are temporally aligned.

17. An encoder comprising at least a processor configured to:

while inter-layer prediction is enabled, encode in a second layer of a scalable multi-layered stream a second layer reference picture of a decoder picture buffer from a first layer reference picture of the decoder picture buffer of the scalable multi-layered stream, wherein the second layer reference picture is indicated as not to be displayed;

encode a flag indicating that a subsequently encoded picture of the second layer is not using any inter-layer prediction, wherein inter-layer prediction is disabled after decoding the flag;

encode a picture block of the subsequently encoded picture at least from the second layer reference picture.

18. The encoder according to claim 17 , wherein to encode in the second layer the second layer reference picture comprises determining the pixel-by-pixel difference between the second layer reference picture and the first layer reference picture and encoding the pixel-by-pixel difference.

19. The encoder according to claim 17 , wherein the first layer is a base layer.

20. The encoder according to claim 17 , wherein the second layer reference picture and the first layer reference picture are temporally aligned.

21. The decoder according to claim 17 , wherein the at least one processor is further configured to encode in the second layer information for identifying the first layer reference picture.