JCTVC-J0482 Mental cross-check of JCTVC-J0215 On NAL unit type [T. C. Thang (UoA)] [late]
JCTVC-J0344 Refinement of random access point support [S. Kanumuri, G. J. Sullivan (Microsoft)]
(Discussion chaired by M. M. Hannuksela.)
(Chaired by M. M. Hannuksela)
This contribution proposed three modifications relating to RAP pictures:
1) A constraint on IDR pictures to provide a simplified form of random access.
2) A constraint that leading pictures of RAP pictures must precede non-leading pictures in decoding order, in order to simplify the scanning of a bitstream for leading pictures.
3) Modify the NAL unit type definitions for RAP pictures to avoid duplicate functionality and convey more RAP type information in the NAL unit type.
Item 2 had been already resolved by notes taken elsewhere.
A comment was expressed that a NAL unit type for IDR picture with leading pictures allowed is desirable.
A comment was expressed that if decodable leading pictures for a CRA picture are originally present but are removed during splicing (including a conversion of the CRA picture to a BLA picture), no HRD parameters for the coded video sequence starting from the BLA picture are readily present in the bitstream.
Decision: Modification 3 was adopted with the addition of a NAL unit type for IDR picture with leading pictures allowed, i.e. the CRA/BLA/IDR NAL unit types are:
Description
|
SAP types possible
|
CRA picture
|
1, 2, 3
|
BLA picture
|
1, 2, 3
|
BLA picture with no associated TFD pictures
|
1, 2
|
BLA picture with no leading pictures
|
1
|
IDR picture with no leading pictures
|
1
|
IDR picture (which may have leading pictures)
|
1, 2
|
A cross-check was promised to be provided by M. M. Hannuksela (not yet available).
To convert a CRA to BLA, the converter would need to consider: 1) no_output_of_prior_pics_flag, 2) rap_pic_id, 3) nal_unit_type.
It was suggested to provide a note in the spec about how the proposed type 7 would be envisioned to be used.
It was suggested that, relative to the proposal, we should have a NUT for an IDR that may have leading pictures.
Decision: Adopt as modified to have a NUT for IDR with leading pictures.
Dostları ilə paylaş: |
