JVET-AM0324 Correction to the Alpha Channel Information SEI message processing order [D. Podborski, A. M. Tourapis (Apple)] [late]

This contribution identifies a potential issue with regards to the order of operations specified for simultaneous use of the alpha_channel_incr_flag and alpha_channel_clip_flag syntax elements in the Alpha Channel Information SEI message of the HEVC specification. The currently specified order seems to produce alpha values outside the intended range and may result in issues when alpha is applied. A normative correction reversing the order of operations is proposed.

It is noted that other changes are planned for the alpha channel information SEI message.

It is agreed that the current behavior is questionable.

Decision: Adopt to VSEI v4 and HEVC.

Further study encouraged to see if AVC has the same problem.

AHG9: Aspects on SEI messages in TuC for VSEI (30)

NNPF SEI messages (2)

Contributions in this area were discussed during 1145–1300 on Saturday 28 June 2025 (chaired by J. Boyce).

JVET-AM0324 Correction to the Alpha Channel Information SEI message processing order

It is noted that the list above may not be complete; if some adoption is missing that is recorded somewhere else in the meeting notes it shall also be considered included.

Remains valid – not updated: JCTVC-V1007 SHVC Test Model 11 (SHM 11) Introduction and Encoder Description [G. Barroux, J. Boyce, J. Chen, M. M. Hannuksela, Y. Ye] [WG 11 N 15778]

JVET-AM1008 Conformance testing for HEVC multiview extended and monochrome profiles [I. Moccagatta, T. Fu, S. Paluri, A. Tourapis] (2025-07-25)

Two new multiview streams are added.

Remains valid – not updated: JVET-AC1009 Common test conditions for SHVC [K. Sühring]

Links to test sequences need to be updated due to the change of the content server.

Remains valid – not updated: JCTVC-O1010 Guidelines for Conformance Testing Bitstream Preparation [T. Suzuki, W. Wan]

Remains valid – not updated: JVET-AJ1011 White paper on HEVC [B. Bross, J.-R. Ohm, G. J. Sullivan, Y.-K. Wang] [AG 3 N 174]

Remains valid – not updated: JVET-AJ1012 Overview of IT systems used in JVET [J.-R. Ohm, I. Moccagatta, K. Sühring, M. Wien]

Update of bug tracking system description expected in next meeting.

Remains valid – not updated: JCT3V-G1003 3D-AVC Test Model 9 [D. Rusanovskyy, F. C. Chen, L. Zhang, T. Suzuki] [WG 11 N 14239]

Remains valid – not updated: JCT3V-K1003 Test Model 11 of 3D-HEVC and MV-HEVC [Y. Chen, G. Tech, K. Wegner, S. Yea] [WG 11 N 15141]

Remains valid – not updated: JVET-AE1013 Common test conditions of 3DV experiments [K. Sühring, M. Wien]

Links to test sequences need to be updated due to the change of the content server.

Remains valid – not updated JCTVC-V1014 Screen Content Coding Test Model 7 Encoder Description (SCM 7) [R. Joshi, J. Xu, R. Cohen, S. Liu, Y. Ye] [WG 11 N 16049]

Remains valid – not updated: JVET-AC1015 Common test conditions for SCM-based screen content coding [K. Sühring]

Links to test sequences need to be updated due to the change of the content server.

Remains valid – not updated: JVET-AH1016 AVC with extensions and corrections (draft 3) [B. Bross, T. Ikai, G. J. Sullivan, A. Tourapis, Y.-K. Wang]

Primary editor: B. Bross.

JVET-AM1017 Support for additional SEI messages in AVC (Draft 3) [K. Sühring, J. Boyce, G. J. Sullivan, Y.-K. Wang] [WG 5 DAM N 363] (2025-07-18)

Primary editor: K. Sühring

A DoC WG 5 N 362 on the CDAM was reviewed and approved on Friday 4 July at 0930-0940.

Changes agreed at this meeting:

Editorial improvements and bug fixes

Resolved bug fixes carried over from JVET-AL1004 were also to be included.

It is noted that the list above may not be complete; if some adoption is missing that is recorded somewhere else in the meeting notes it shall also be considered included.

JVET-AM1018 HEVC with extensions and corrections (Draft 2) [G. J. Sullivan, Y.-K. Wang] (2025-09-30)

Primary editor: Y.-K. Wang.

To prepare the next edition of H.265 – changes from the differential text JVET-AM1006 (e.g., new SEI messages) to be included.

No output: JVET-Axx1019 through JVET-Axx1099

Remains valid – not updated JVET-AA1100 Common Test Conditions for HM Video Coding Experiments [K. Sühring, K. Sharman]

This specifies only the CTC for non-4:2:0 colour formats. The corresponding document for VVC is JVET-T2013, with no unification yet.

Links to test sequences need to be updated due to the change of the content server.

No output: JVET-Axx2001

Remains valid – not updated: JVET-AH2002 Algorithm description for Versatile Video Coding and Test Model 22 (VTM 22) [Y. Ye, A. Browne, S. Kim] [WG 5 N 284]

Primary editor: Y. Ye.

New elements from notes elsewhere in this report (kept for future use):

…

It is noted that the list above may not be complete; if some adoption is missing that is recorded somewhere else in the meeting notes it shall also be considered included.

It was suggested that editorial improvements submitted as input to the next meeting would be welcome.

Remains valid – not updated: JVET-AJ2003 Guidelines for VTM-based software development [F. Bossen, X. Li, K. Sühring]

Remains valid – not updated: JVET-T2004 Algorithm descriptions of projection format conversion and video quality metrics in 360Lib (Version 12) [Y. Ye, J. Boyce]

JVET-AM2005 Additions and corrections for VVC version 4 (Draft 13) [G. J. Sullivan, B. Bross, M. M. Hannuksela, Y.-K. Wang] (2025-08-01)

Changes agreed at this meeting:

JVET-AM0324 Correction to the Alpha Channel Information SEI message processing order

NNPF