Temporal identifier constraints for SEI messages
A video coding mechanism is disclosed. The mechanism includes encoding a coded picture in one or more video coding layer (VCL) network abstraction layer (NAL) units in a bitstream. A non-VCL NAL unit is encoded into the bitstream such that a temporal identifier (TemporalId) for the non-VCL NAL unit is constrained to be equal to a TemporalId of an access unit (AU) containing the non-VCL NAL unit when a NAL unit type (nal_unit_type) of the non-VCL NAL indicates a supplemental enhancement information (SEI) message. A set of bitstream conformance tests is performed on the bitstream based on the SEI message. The bitstream is stored for communication toward a decoder.
1. A method implemented by a decoder, the method comprising:
receiving a bitstream comprising a coded picture in one or more video coding layer (VCL) network abstraction layer (NAL) units and a non-VCL NAL unit, wherein a temporal identifier (TemporalId) for the non-VCL NAL unit is constrained to be equal to a TemporalId of an access unit (AU) containing the non-VCL NAL unit when a NAL unit type (nal_unit_type) of the non-VCL NAL is equal to a prefix supplemental enhancement information (SEI) NAL unit type (PREFIX_SEI_NUT) or a suffix SEI NAL unit type (SUFFIX_SEI_NUT), wherein the non-VCL NAL unit includes a scalable nesting SEI message with a payload type set to one hundred thirty-three, wherein the scalable nesting SEI message contains one or more scalable-nested SEI messages, wherein the scalable nesting SEI message includes an output layer set (OLS) flag equal to one when the scalable-nested SEI messages apply to an OLS and equal to zero when the scalable-nested SEI messages apply to a layer, and wherein the scalable nesting SEI message includes a scalable nesting number of SEIs minus one (num_seis_minus1) plus one that specifies a number of the scalable-nested SEI messages with a value constrained to a range of 0 to 63, inclusive;
deriving the TemporalId for the non-VCL NAL unit based on a NAL unit header temporal identifier plus one (nuh_temporal_id_plus1) syntax element in the non-VCL NAL unit; and
decoding the coded picture from the one or more VCL NAL units to produce a decoded picture.
2. The method of claim 1 , wherein the nal_unit_type of the non-VCL NAL is equal to the PREFIX_SEI_NUT.
3. The method of claim 1 , wherein the nal_unit_type of the non-VCL NAL is equal to the SUFFIX_SEI_NUT.
4. The method of claim 1 , wherein the coded picture is decoded from the one or more VCL NAL units based on a SEI message in the non-VCL NAL unit.
5. The method of claim 1 , further comprising deriving the TemporalId for the non-VCL NAL unit as follows:
TemporalId
=
nuh_temporal
_id
_plus1
-
1.
6. The method of claim 5 , wherein a value of nuh_temporal_id_plus1 is not equal to zero.
7. The method of claim 1 , wherein a TemporalId of the one or more VCL NAL units is constrained to be the same for all VCL NAL units in a same AU.
8. The method of claim 1 , wherein the scalable nesting SEI message includes a number of OLSs minus1 (num_olss_minus1) plus 1 that specifies a number of OLSs to which the scalable-nested SEI messages apply.
9. A method implemented by an encoder, the method comprising:
encoding a coded picture in one or more video coding layer (VCL) network abstraction layer (NAL) units in a bitstream;
encoding into the bitstream a non-VCL NAL unit such that a NAL unit header temporal identifier plus one (nuh_temporal_id_plus1) for the non-VCL NAL unit is constrained to be equal to a nuh_temporal_id_plus1 of an access unit (AU) containing the non-VCL NAL unit when a NAL unit type (nal_unit_type) of the non-VCL NAL is a supplemental enhancement information (SEI) message, and wherein the non-VCL NAL unit includes a scalable nesting SEI message with a payload type set to one hundred thirty-three, wherein the scalable nesting SEI message contains one or more scalable-nested SEI messages, wherein the scalable nesting SEI message includes an output layer set (OLS) flag equal to one when the scalable-nested SEI messages apply to an OLS and equal to zero when the scalable-nested SEI messages apply to a layer, and wherein the scalable nesting SEI message includes a scalable nesting number of SEIs minus one (num_seis_minus1) plus one that specifies a number of the scalable-nested SEI messages with a value constrained to a range of 0 to 63, inclusive;
performing a set of bitstream conformance tests on the bitstream based on the SEI message.
10. The method of claim 9 , wherein the nal_unit_type of the non-VCL NAL is equal to a prefix SEI NAL unit type (PREFIX_SEI_NUT).
11. The method of claim 9 , wherein the nal_unit_type of the non-VCL NAL is equal to a suffix SEI NAL unit type (SUFFIX_SEI_NUT).
12. The method of claim 9 , wherein a value of nuh_temporal_id_plus1 is not equal to zero.
13. The method of claim 9 , wherein a nuh_temporal_id_plus1 of the one or more VCL NAL units is constrained to be the same for all VCL NAL units in a same AU.
14. A video decoding device comprising:
a receiver configured to receive a bitstream comprising a coded picture in one or more video coding layer (VCL) network abstraction layer (NAL) units and a non-VCL NAL unit, wherein a temporal identifier (TemporalId) for the non-VCL NAL unit is constrained to be equal to a TemporalId of an access unit (AU) containing the non-VCL NAL unit when a NAL unit type (nal_unit_type) of the non-VCL NAL is equal to a prefix supplemental enhancement information (SEI) NAL unit type (PREFIX_SEI_NUT) or a suffix SEI NAL unit type (SUFFIX_SEI_NUT), and wherein the non-VCL NAL unit includes a scalable nesting SEI message with a payload type set to one hundred thirty-three, wherein the scalable nesting SEI message contains one or more scalable-nested SEI messages, wherein the scalable nesting SEI message includes an output layer set (OLS) flag equal to one when the scalable-nested SEI messages apply to an OLS and equal to zero when the scalable-nested SEI messages apply to a layer, and wherein the scalable nesting SEI message includes a scalable nesting number of SEIs minus one (num_seis_minus1) plus one that specifies a number of the scalable-nested SEI messages with a value constrained to a range of 0 to 63, inclusive; and
one or more processors coupled to the receiver and configured to:
derive the TemporalId for the non-VCL NAL unit based on a NAL unit header temporal identifier plus one (nuh_temporal_id_plus1) syntax element in the non-VCL NAL unit; and
decode the coded picture from the one or more VCL NAL units to produce a decoded picture.
15. The video decoding device of claim 14 , wherein the nal_unit_type of the non-VCL NAL is equal to the PREFIX_SEI_NUT.
16. The video decoding device of claim 15 , wherein the nal_unit_type of the non-VCL NAL is equal to the SUFFIX_SEI_NUT.
17. The video decoding device of claim 16 , wherein the coded picture is decoded from the one or more VCL NAL units based on a SEI message in the non-VCL NAL unit.
18. The video decoding device of claim 17 , further comprising deriving the TemporalId for the non-VCL NAL unit as follows:
TemporalId
=
nuh_temporal
_id
_plus1
-
1.
19. The video decoding device of claim 18 , wherein a value of nuh_temporal_id_plus1 is not equal to zero.
20. The video decoding device of claim 14 , wherein a TemporalId of the one or more VCL NAL units is constrained to be the same for all VCL NAL units in a same AU.