Method for signaling dependent and independent picture header

1. A method of reconstructing in a decoder a coded enhancement layer picture, the method being performed by at least one processor, and the method comprising:

decoding at least one independent picture header network abstraction layer (NAL) unit of a coded picture of a reference layer, the coded picture of the reference layer being referenced by the coded enhancement layer picture;

decoding a dependent picture header NAL unit of the coded enhancement layer picture; and

performing picture header prediction comprising either one or both of:

predicting at least one value of at least one syntax element of the dependent picture header NAL unit from at least one value of at least one corresponding syntax element of the at least one independent picture header NAL unit; and

inferring at least one value of a non-present syntax element of the dependent picture header NAL unit to be equal to at least one value of a present syntax element of the at least one independent picture header NAL unit,

wherein the at least one independent picture header NAL unit and the dependent picture header NAL unit are each an NAL unit that includes a NAL unit type syntax element that has a value indicating a picture header NAL unit.

2. The method of claim 1 , further comprising signaling a delta value between the predicted at least one value of the at least one syntax element of the dependent picture header NAL unit and the at least one value of the at least one corresponding syntax element of the at least one independent picture header NAL unit.

3. The method of claim 1 , further comprising determining that the coded picture comprises the at least one independent picture header NAL unit, based on a flag of the at least one independent picture header NAL unit; and

determining that the coded enhancement layer picture comprises the dependent picture header NAL unit, based on a flag of the dependent picture header NAL unit.

4. The method of claim 1 , further comprising determining that the coded picture comprises the at least one independent picture header NAL unit, based on a unit type of the coded picture; and

determining that the coded enhancement layer picture comprises the dependent picture header NAL unit, based on a unit type of the coded enhancement layer picture.

5. The method of claim 1 , wherein the at least one independent picture header NAL unit directly precedes a video coding layer NAL unit in the coded picture.

6. The method of claim 1 , wherein the dependent picture header NAL unit directly precedes a video coding layer NAL unit in the coded enhancement layer picture.

7. The method of claim 1 , wherein each of the coded picture and the coded enhancement layer picture comprises a plurality of video coding layer NAL units and a plurality of picture header NAL units directly preceding the plurality of video coding layer NAL units.

8. An apparatus for reconstructing in a decoder a coded enhancement layer picture, the apparatus comprising:

at least one memory configured to store computer program code; and

at least one processor configured to access the at least one memory and operate according to the computer program code, the computer program code comprising:

first decoding code configured to cause the at least one processor to decode at least one independent picture header network abstraction layer (NAL) unit of a coded picture of a reference layer, the coded picture of the reference layer being referenced by the coded enhancement layer picture;

second decoding code configured to cause the at least one processor to decode a dependent picture header NAL unit of the coded enhancement layer picture; and

performing code configured to cause the at least one processor to perform picture header prediction comprising either one or both of:

predicting at least one value of at least one syntax element of the dependent picture header NAL unit from at least one value of at least one corresponding syntax element of the at least one independent picture header NAL unit; and

inferring at least one value of a non-present syntax element of the dependent picture header NAL unit to be equal to at least one value of a present syntax element of the at least one independent picture header NAL unit,

wherein the at least one independent picture header NAL unit and the dependent picture header NAL unit are each an NAL unit that includes a NAL unit type syntax element that has a value indicating a picture header NAL unit.

9. The apparatus of claim 8 , further comprising signaling code configured to cause the at least one processor to signal a delta value between the predicted at least one value of the at least one syntax element of the dependent picture header NAL unit and the at least one value of the at least one corresponding syntax element of the at least one independent picture header NAL unit.

10. The apparatus of claim 8 , further comprising determining code configured to cause the at least one processor to:

determine that the coded picture comprises the at least one independent picture header NAL unit, based on a flag of the at least one independent picture header NAL unit; and

determine that the coded enhancement layer picture comprises the dependent picture header NAL unit, based on a flag of the dependent picture header NAL unit.

11. The apparatus of claim 8 , further comprising determining code configured to cause the at least one processor to:

determine that the coded picture comprises the at least one independent picture header NAL unit, based on a unit type of the coded picture; and

determine that the coded enhancement layer picture comprises the dependent picture header NAL unit, based on a unit type of the coded enhancement layer picture.

12. The apparatus of claim 8 , wherein the at least one independent picture header NAL unit directly precedes a video coding layer NAL unit in the coded picture.

13. The apparatus of claim 8 , wherein the dependent picture header NAL unit directly precedes a video coding layer NAL unit in the coded enhancement layer picture.

14. The apparatus of claim 8 , wherein each of the coded picture and the coded enhancement layer picture comprises a plurality of video coding layer NAL units and a plurality of picture header NAL units directly preceding the plurality of video coding layer NAL units.

15. A non-transitory computer-readable storage medium storing instructions that cause at least one processor to:

decode at least one independent picture header network abstraction layer (NAL) unit of a coded picture of a reference layer, the coded picture of the reference layer being referenced by a coded enhancement layer picture;

decode a dependent picture header NAL unit of the coded enhancement layer picture; and

perform picture header prediction comprising either one or both of:

predicting at least one value of at least one syntax element of the dependent picture header NAL unit from at least one value of at least one corresponding syntax element of the at least one independent picture header NAL unit; and

inferring at least one value of a non-present syntax element of the dependent picture header NAL unit to be equal to at least one value of a present syntax element of the at least one independent picture header NAL unit,

wherein the at least one independent picture header NAL unit and the dependent picture header NAL unit are each an NAL unit that includes a NAL unit type syntax element that has a value indicating a picture header NAL unit.

16. The non-transitory computer-readable storage medium of claim 15 , wherein the instructions further cause the at least one processor to signal a delta value between the predicted at least one value of the at least one syntax element of the dependent picture header NAL unit and the at least one value of the at least one corresponding syntax element of the at least one independent picture header NAL unit.

17. The non-transitory computer-readable storage medium of claim 15 , wherein the instructions further cause the at least one processor to:

determine that the coded picture comprises the at least one independent picture header NAL unit, based on a flag of the at least one independent picture header NAL unit; and

determine that the coded enhancement layer picture comprises the dependent picture header NAL unit, based on a flag of the dependent picture header NAL unit.

18. The non-transitory computer-readable storage medium of claim 15 , wherein the instructions further cause the at least one processor to:

determine that the coded picture comprises the at least one independent picture header NAL unit, based on a unit type of the coded picture; and

determine that the coded enhancement layer picture comprises the dependent picture header NAL unit, based on a unit type of the coded enhancement layer picture.

19. The non-transitory computer-readable storage medium of claim 15 , wherein the at least one independent picture header NAL unit directly precedes a video coding layer NAL unit in the coded picture.

20. The non-transitory computer-readable storage medium of claim 15 , wherein the dependent picture header NAL unit directly precedes a video coding layer NAL unit in the coded enhancement layer picture.