[FFmpeg-devel] [PATCH] avformat/oggparseogm: sync avctx w/ codecpar

Chris Cunningham chcunningham at chromium.org
Mon Feb 11 23:55:49 EET 2019

On Fri, Feb 8, 2019 at 2:37 PM Michael Niedermayer <michaelni at gmx.at> wrote:

> ogg allows chaining streams when they have differing serial numbers
> https://xiph.org/ogg/doc/oggstream.html
> i think ive seen actual files doing this
> ogg_replace_stream() might assign these into existing avstreams i think

If I'm reading this correctly, I think that should always happen at the
boundary of a new ogg page, meaning it wouldn't rely on this multiple
headers logic?

I found the commit where this was introduced

With the description:
This fixes some old ogm files that had the 3rd vorbis header after a data
packet in another stream. This is invalid in ogg, but this change shouldn't
affect the behaviour of any valid file.

So, I don't think we're going to find spec text for this. No spec for OGM
and committer indicates its not valid Ogg. I'm guessing we want to still
support these ogm files?

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