Parameter set signaling in digital video

1. A method of bitstream processing, comprising:

obtaining a first parameter set identifier from a data unit containing bits corresponding to a coded video region;

activating a first parameter set with its identifier equal to the first parameter set identifier;

obtaining a tool flag from the first parameter set corresponding to the first parameter set identifier;

determining, from the tool flag, that a tool parameter of a tool corresponding to the tool flag is present or enabled for decoding the coded video region, wherein the tool corresponds to a video coding technique;

obtaining, based on the determining, a second parameter set identifier from the first parameter set;

activating a second parameter set with its identifier equal to the second parameter set identifier, wherein the second parameter set includes the tool the tool parameter of a single tool present in the second parameter set;

obtaining the tool parameter from the second parameter set corresponding to the second parameter set identifier; and

decoding the video region using the tool parameter.

2. The method of claim 1 , wherein the video region corresponds to a video picture.

3. The method of claim 1 , wherein the video region is smaller than a video picture.

4. The method of claim 1 , wherein the video coding technique is based on coding parameters that are common to multiple coding blocks in the coded video region.

5. The method of claim 1 , further including:

obtaining another tool flag from the first parameter set;

deciding, from the tool flag, that another tool parameter of another tool corresponding to the another tool flag is present or enabled for decoding the coded video region;

obtaining, based on the deciding, a third parameter set identifier; and

obtaining the another tool parameter from a third parameter set corresponding to the third parameter set identifier; and

wherein the decoding the video region includes decoding the video region using the another tool parameter.

6. The method of claim 5 , wherein network abstraction layer (NAL) units containing the second parameter set, the third parameter set and the first parameter set have a same NAL unit type.

7. The method of claim 5 , wherein a NAL unit containing the third parameter set is a same NAL unit type as a NAL unit containing the first parameter set.

8. The method of claim 7 , wherein the network abstraction layer unit type is indicated by a fixed length code word in a NAL unit header.

9. The method of claim 1 , wherein the obtaining the second parameter set identifier includes obtaining the second parameter set identifier from the first parameter set.

10. The method of claim 6 , wherein the third parameter set identifier is obtained from the first parameter set.

11. A method of encoding a video region, comprising:

determining a tool parameter of a tool used in encoding a video region, wherein the tool represents a video coding technique;

generating a first parameter set that is identified by a first parameter set identifier;

including, in the first parameter set, a tool flag corresponding to the tool, wherein the tool flag is set to a value indicating that the tool parameter is present or enabled for encoding the video region;

including the tool parameter in the first parameter set using a second parameter set identifier associated with a second parameter set, wherein the second parameter set includes the tool the tool parameter of a single tool present in the second parameter set;

coding the first parameter set identifier in a header of the video region; and

coding the video region using the tool parameter.

12. The method of claim 11 , wherein the including step comprises:

setting, in a case that the tool parameter is identical to an existing tool parameter in an existing tool parameter set, the second parameter set identifier equal to a parameter set identifier of the existing tool parameter set;

generating, in case that the tool parameter is not identical to any existing tool parameter in any existing parameter set, using the second parameter set identifier having a different value than the first parameter set identifier.

13. The method of claim 11 , wherein the video region corresponds to a video picture.

14. The method of claim 11 , wherein the video region is smaller than a video picture.

15. The method of claim 11 , wherein the video coding technique is based on coding parameters that are common to multiple coding blocks in the coded video region.

16. The method of claim 11 , further including:

including, in the first parameter set, another tool flag corresponding to another tool, wherein the another tool flag is set to a value indicating that another tool parameter corresponding to the another tool is present or enabled for encoding the video region;

including the another tool parameter in the first parameter set using a third parameter set identifier;

wherein the coding the video region is performed using the another tool parameter.

17. The method of claim 11 , wherein the second parameter set identifier is coded in the first parameter set.

18. An apparatus comprising a processor configured to implement a method, comprising:

obtaining a first parameter set identifier from a data unit containing bits corresponding to a coded video region;

activating a first parameter set with its identifier equal to the first parameter set identifier;

obtaining a tool flag from the first parameter set corresponding to the first parameter set identifier;

determining, from the tool flag, that a tool parameter of a tool corresponding to the tool flag is present or enabled for decoding the coded video region, wherein the tool corresponds to a video coding technique;

obtaining, based on the determining, a second parameter set identifier;

activating a second parameter set with its identifier equal to the second parameter set identifier, wherein the second parameter set includes the tool the tool parameter of a single tool present in the second parameter set;

obtaining the tool parameter from a second parameter set corresponding to the second parameter set identifier; and

decoding the video region using the tool parameter.

19. The apparatus of claim 18 , wherein the video coding technique is based on coding parameters that are common to multiple coding blocks in the coded video region.

20. The apparatus of claim 18 , further including:

obtaining another tool flag from the first parameter set;

deciding, from the tool flag, that another tool parameter of another tool corresponding to the another tool flag is present or enabled for decoding the coded video region;

obtaining, based on the deciding, a third parameter set identifier; and

obtaining the another tool parameter from a third parameter set corresponding to the third parameter set identifier; and

wherein the decoding the video region includes decoding the video region using the another tool parameter.