[AVTCORE] Benjamin Kaduk's No Objection on draft-ietf-payload-vp9-14: (with COMMENT)

Benjamin Kaduk via Datatracker <noreply@ietf.org> Thu, 03 June 2021 22:06 UTC

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Subject: [AVTCORE] Benjamin Kaduk's No Objection on draft-ietf-payload-vp9-14: (with COMMENT)
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Benjamin Kaduk has entered the following ballot position for
draft-ietf-payload-vp9-14: No Objection

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COMMENT:
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Thanks for addressing my Discuss point, and comments!
I spotted a few maybe nits in the -14 while reviewing the diff.

Section 3

   A Picture Group is a recurring pattern of spatial and temporal
   dependencies which In this mode, each packet has an index to refer to

Looks like an editing remnant up to "In this mode".

Section 4.2

   I:  Picture ID (PID) present.  When set to one, the OPTIONAL PID MUST
      be present after the mandatory first octet and specified as below.
      Otherwise, PID MUST NOT be present.  If the V bit was set in the
      stream's most recent start of a keyframe (i.e. the SS field was
      present, and non-flexible scalability mode is in use), then this
      bit MUST be set on every packet.

I may (still?) be confused, but I think the "non-flexible scalability mode is
in use" belongs outside the parentheses, as it's an additional separate
precondition from "V bit is set" for "this bit MUST be set".  That is, IIUC,
non-flexible scalability mode requires SS and requires PIDs in every packet,
but it's permitted to send SS in flexible scalability mode, and in the latter
case it's permitted (but unexpected?) to omit PIDs from (some) packets.

Section 4.2.1

   In a scalable stream sent with a fixed pattern, the SS data SHOULD be
   included in the first packet of every key frame.  This is a packet
   with P bit equal to zero, SID or Lis not the bit equal to zero, and B
   bit equal to 1.  [...]

I think there's some editing churn here as well, at least a space in "L is"
but possibly more qualifiers about SID being zero vs L being the bit equal to
zero.