Method for alignment across layers in coded video stream
A method, computer program, and computer system is provided for aligning across layers in a coded video stream. A video bitstream having multiple layers is decoded. One or more subpicture regions are identified from among the multiple layers of the decoded video bitstream, the subpicture regions including a background region and one or more foreground subpicture regions. An enhanced subpicture is decoded and displayed based on a determination that a foreground subpicture region is selected. The background region is decoded and displayed based on a determination that a foreground subpicture region was not selected.
1. A method of aligning across layers in a coded video stream, executable by a processor, comprising:
decoding a video bitstream having multiple layers;
identifying one or more subpicture regions from among the multiple layers of the decoded video bitstream; and
aligning the one or more subpictures across the multiple layers,
wherein, based on a network abstraction layer (NAL) unit having a nal_unit_type equal to STSA_NUT, a TemporalID of a NAL unit in a reference picture list is different than a TemporalID of the NAL unit having the nal_unit_type equal to STSA_NUT, wherein the NAL unit in the reference picture list comprises a picture parameter set (PPS) NAL unit, and wherein the NAL unit having the NAL unit type equal to STSA_NUT comprises a coded slice NAL unit.
2. The method of claim 1 , wherein the PPS NAL unit and the coded slice NAL unit are included in a same access unit (AU).
3. The method of claim 1 , wherein a first access unit includes the PPS NAL unit and a step-wise temporal sublayer access (STSA) NAL unit, and a second access unit includes the coded slice NAL unit.
4. The method of claim 1 , wherein a nuh_layer_id of the NAL unit in the reference picture list is different from a nuh_layer_id of the NAL unit having the nal_unit_type equal to STSA NUT.
5. The method of claim 1 , wherein layout information of subpicture regions is signaled by parameter set data.
6. The method of claim 5 , wherein the layout information comprises a size and a position associated with the subpicture regions.
7. The method of claim 5 , wherein one or more of the subpicture regions may be relocated and displayed based on the layout information.
8. The method of claim 1 , wherein each subpicture region may be coded as an independent layer corresponding to a local region having a unique layer identification value.
9. The method of claim 8 , wherein each of the subpicture regions corresponding to the independent layers has a unique picture order count value within a respective access unit.
10. A computer system for aligning across layers in a coded video stream, the computer system comprising:
one or more computer-readable non-transitory storage media configured to store computer program code; and
one or more computer processors configured to access said computer program code and operate as instructed by said computer program code, said computer program code including:
first decoding code configured to cause the one or more computer processors to decode a video bitstream having multiple layers;
identifying code configured to cause the one or more computer processors to identify one or more subpicture regions from among the multiple layers of the decoded video bitstream; and
aligning code configured to cause the one or more computer processors to align the one or more subpictures across the multiple layers, wherein based on a network abstraction layer (NAL) unit having a nal_unit_type equal to STSA_NUT, a TemporalID of a NAL unit in a reference picture list is different than a TemporalID of the NAL unit having a nal_unit_type equal to STSA_NUT, wherein the NAL unit in the reference picture list comprises a picture parameter set (PPS) NAL unit, and wherein the NAL unit having the NAL unit type equal to STSA_NUT comprises a coded slice NAL unit.
11. The computer system of claim 10 , wherein the PPS NAL unit and the coded slice NAL unit are included in a same access unit (AU).
12. The computer system of claim 10 , wherein a first access unit includes the PPS NAL unit and a step-wise temporal sublayer access (STSA) NAL unit, and a second access unit includes the coded slice NAL unit.
13. The computer system of claim 10 , wherein a nuh_layer_id of the NAL unit in the reference picture list is different from a nuh_layer_id of the NAL unit having the nal_unit_type equal to STSA NUT.
14. The computer system of claim 10 , wherein layout information of subpicture regions is signaled by parameter set data.
15. The computer system of claim 14 , wherein one or more of the subpicture regions may be relocated and displayed based on the layout information.
16. The computer system of claim 10 , wherein each subpicture region may be coded as an independent layer corresponding to a local region having a unique layer identification value.
17. The computer system of claim 16 , wherein each of the subpicture regions corresponding to the independent layers has a unique picture order count value within a respective access unit.
18. A non-transitory computer readable medium having stored thereon a computer program for aligning across layers in a coded video stream, the computer program configured to cause one or more computer processors to:
decode a video bitstream having multiple layers;
identify one or more subpicture regions from among the multiple layers of the decoded video bitstream; and
align the one or more subpictures across the multiple layers,
wherein, based on a network abstraction layer (NAL) unit having a nal_unit_type equal to STSA_NUT, a TemporalID of a NAL unit in a reference picture list is different than a TemporalID of the NAL unit having a nal_unit_type equal to STSA_NUT wherein the NAL unit in the reference picture list comprises a picture parameter set (PPS) NAL unit, and wherein the NAL unit having the NAL unit type equal to STSA_NUT comprises a coded slice NAL unit.