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

Jonathan Lennox <> Fri, 04 June 2021 20:09 UTC

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From: Jonathan Lennox <>
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Date: Fri, 4 Jun 2021 16:09:26 -0400
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Subject: Re: [AVTCORE] Benjamin Kaduk's No Objection on draft-ietf-payload-vp9-14: (with COMMENT)
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> On Jun 3, 2021, at 6:06 PM, Benjamin Kaduk via Datatracker <> wrote:
> Benjamin Kaduk has entered the following ballot position for
> draft-ietf-payload-vp9-14: No Objection
> ----------------------------------------------------------------------
> ----------------------------------------------------------------------
> Thanks for addressing my Discuss point, and comments!
> I spotted a few maybe nits in the -14 while reviewing the diff.

Thanks, all of these are correct, I’ve published a -15.

> 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.