Implicit determination of collocated picture for temporal prediction

1. A method comprising:

determining, by a computing device, a block of a current picture;

determining, by the computing device, a prediction type associated with the block;

selecting, by the computing device, one of a first list of reference pictures or a second list of reference pictures for the block by checking the prediction type associated with the block without communication of information between an encoder and a decoder indicating which of the lists of reference pictures was selected;

selecting, by the computing device, a reference picture in the selected one of the lists of reference pictures without communication of information between the encoder and the decoder indicating which of the reference pictures to select; and

using a collocated block within the selected reference picture in a temporal prediction process for the block, wherein one of:

the first list of reference pictures is selected no matter what the prediction type; or

the second list of reference pictures is selected no matter what the prediction type.

2. The method of claim 1 , wherein prediction type comprises a slice type for a slice associated with the block.

3. The method of claim 1 , wherein the prediction type is equal to P.

4. The method of claim 1 , wherein the prediction type is equal to B.

5. The method of claim 1 , wherein a first reference picture in the selected list of reference pictures is selected as the reference picture regardless of the prediction type.

6. The method of claim 1 , wherein a reference picture in the selected one of the lists of reference pictures that is closest in temporal distance to the current picture is selected regardless of the prediction type.

7. A method comprising:

determining, by a computing device, a block of a current picture;

determining, by the computing device, one of a first list of reference pictures and a second list of reference pictures for the block no matter what prediction type is associated with the block, wherein an encoder or a decoder always selects the one of the first list of reference pictures or the second list of reference pictures for all blocks being encoded or decoded for at least a section of the current picture implicitly without communication of information between the encoder and the decoder indicating which of the first list of reference pictures or the second list of reference pictures was selected; and

setting, by the computing device, a reference picture in the selected one of the first list of reference pictures and the second list of reference pictures as a reference picture for the block, wherein a collocated block within the selected reference picture is used in a temporal prediction process for the block.

8. The method of claim 7 , wherein determining one of the first list of reference pictures and the second list of reference pictures for the block comprises always determining the first list of reference pictures no matter what the prediction type.

9. The method of claim 7 , wherein determining one of the first list of reference pictures and the second list of reference pictures for the block comprises always determining the second list of reference pictures no matter what the prediction type.

10. A decoder comprising:

one or more computer processors; and

a non-transitory computer-readable storage medium comprising instructions that, when executed, control the one or more computer processors to be configured for:

determining a block of a current picture;

determining a prediction type associated with the block;

selecting one of a first list of reference pictures or a second list of reference pictures for the block, wherein the decoder selects the one of the lists of reference pictures by checking the prediction type and without receiving communication of information from an encoder indicating which of the lists of reference pictures was selected;

selecting a reference picture in the selected one of the lists of reference pictures as a reference picture for the block without receiving communication of information from the encoder indicating which of the reference pictures to select; and

using a collocated block within the selected reference picture in a temporal prediction process in a decoding process for the block, wherein when the prediction type is equal to B, the second list of reference pictures is selected.

11. The decoder of claim 10 , wherein prediction type comprises a slice type for a slice associated with the block.

12. A decoder comprising:

one or more computer processors; and

a non-transitory computer-readable storage medium comprising instructions that, when executed, control the one or more computer processors to be configured for:

determining a block of a current picture;

determining a prediction type associated with the block;

selecting one of a first list of reference pictures or a second list of reference pictures for the block, wherein the decoder selects the one of the lists of reference pictures by checking the prediction type and without receiving communication of information from an encoder indicating which of the lists of reference pictures was selected;

selecting a reference picture in the selected one of the lists of reference pictures as a reference picture for the block without receiving communication of information from the encoder indicating which of the reference pictures to select; and

using a collocated block within the selected reference picture in a temporal prediction process in a decoding process for the block, wherein a reference picture in the selected one of the lists of reference pictures that is closest in temporal distance to the current picture is selected regardless of the prediction type.