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22nd Meeting: by teleconference, April 2021 2021-04-13 18:13
AHG9: On the scalability dimension information SEI message
Authors: Yifan Wang ByteDance Ye-Kui Wang ByteDance Li Zhang ByteDance
Abstract
This document contains the draft text for changes to the versatile supplemental enhancement information messages for coded video bitstreams (VSEI) standard (Rec. ITU-T H.274 ISO/IEC 23002-7), to specify additional SEI messages, including the annotated regions SEI message, the alpha channel information SEI message, the depth representation information SEI message, the multiview acquisition information SEI message, the SDI SEI message, and the extended dependent random access point (DRAP) indication SEI message. The draft text also includes text changes for some technical corrections and editorial improvements.
Meeting Notes
JVET-V0063 AHG9: On the scalability dimension information SEI message [Y. Wang, Y.-K. Wang, L. Zhang (Bytedance)]

This contribution was discussed in sesssion 9 at 1300 on Thursday 22 April (chaired by GJS).

This SEI message is under development for v2 of VVC+VSEI.

This contribution proposes the following changes to the scalability dimension information SEI message:

  1. Change sdi_view_id_len to sdi_view_id_len_minus1.
  2. Change the condition for inference of sdi_view_id_val[ i ] equal to 0 from "when not present" to "when sdi_multiview_info_flag is equal to 0". Offline study of this aspect was conducted. This was further discussed in sesssion 18b at 1720 on Monday 26 April 2021 (chaired by GJS) and it was reported that this ID value is not used when it is inferred, so it was agreed to just remove the inference rule.
  3. Add inference of sdi_aux_id[ i ] to be equal to 0 when sdi_auxiliary_info_flag is equal to 0.
  4. Add the following constraints to the semantics of scalability dimension information SEI message:
    1. When an SDI SEI message is present in any AU of a CVS, an SDI SEI message shall be present for the first AU of the CVS.
    2. All SDI SEI messages that apply to the same CVS shall have the same content. It was agreed that this should refer to presence in a CVS, not “applying to the” CVS.
    3. An SDI SEI message shall not be contained in a scalable nesting SEI message.
    4. It is a requirement of bitstream conformance that sdi_max_layers_minus1 shall be equal to vps_max_layers_minus1. It was asked what could happen if a version 1 bitstream editor processes a version 2 bitstream, removes layers from it, and changes the value of vps_max_layers_minus1. This is a similar issue as for when we added bitstream manifest and prefix SEI messages to HEVC. This was further discussed in sesssion 18b at 1725 on Monday 26 April 2021 (chaired by GJS) and it was suggested by a participant to include the layer ID in the loop and not specify a requirement of matching the VPS syntax element. This suggestion was agreed. It was commented that in the VVC context there is no good reason to change layer IDs; we only need to worry about removal of layers, and changes of layer ID would have other undesired side effects.

The text changes for the proposals in JVET-V0063 (this contribution), JVET-V0064, and JVET-V0065 were included in the attachment to JVET-V0063.

It was remarked that any persistence beyond the current CVS could cause a problem with bitstream splicing. It was thus agreed that there should be no such persistence.

Decision (cleanup): Adopted as modified by the four “agreed” aspects noted above.

References:
JVET-U0082 JVET-U0084 JVET-U0086 JVET-U2006
Cited:
JVET-V0009 JVET-V0064 JVET-V0065 JVET-V2006 JVET-W0002 JVET-W0003 JVET-W0083 JVET-W2006 JVET-X2006 JVET-Y2006
ARCHIVE v1 :
JVET-V0063-v1.docx JVET-V0063-v1_attachment.docx
Decisions
adopted
Decision (cleanup): Adopted as modified by the four “agreed” aspects noted above.
Citation