Re: [Cellar] AV1 mapping Matroska

Michael Niedermayer <michael@niedermayer.cc> Mon, 02 July 2018 10:35 UTC

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Date: Mon, 2 Jul 2018 12:34:55 +0200
From: Michael Niedermayer <michael@niedermayer.cc>
To: cellar@ietf.org
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Subject: Re: [Cellar] AV1 mapping Matroska
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Hi

On Mon, Jul 02, 2018 at 09:47:45AM +0200, Moritz Bunkus wrote:
> Hey,
> 
> > Looking at the term "coded video sequence" (CVS) in other codecs (H.264
> > and H.265) it seems it's a common term. And for those codec one Segment
> > correspond to one CVS, with the parameters of that CVS stored in the
> > CodecPrivate (SPS + PPS for H.264 for example). So we should probably go
> > in that simple way.
> 
> I have quite a lot of h.264 samples here, mainly M2TS from DVB, where
> SPS/PPS change mid-stream, often multiple times. For such files the first
> occurrences of SPS/PPS make up the AvcC in CodecPrivate, but all key frames
> are still prefixed with the currently active SPS/PPS — because that's the
> only way to signal that stuff has actually changed.

IMHO All SPS/PPS should be in the "global header" (CodecPrivate) which the
global header applies to, not just the first.
This way an application can know all resolutions, aspect ratios and so on
from just the header without the need to scan through all random access
points.


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato