[FFmpeg-devel] [PATCH] movenc: support GPMF track (gpmd) remuxing

[Clément Bœsch]

On Fri, Jul 21, 2017 at 03:03:19PM +0100, Derek Buitenhuis wrote:
> On 7/21/2017 2:55 PM, Clément Bœsch wrote:
> > It's basically the same layout for every stsd sample description. Check
> > the other tags that extend that layout, the also have that data ref idx to
> > 1. I think I copied from the rtp code, but it's the same for the other as
> > well. This gpmd atom just extends the stsd sample description with a
> > reserved 32-bit value.
> 
> How very useful.
> 

Well, I didn't write the ISO specifications.

If you're refering to the reserved 32-bit value, I suppose it's meant to
allow extensions in the future. Typically it could be reused as a version
or version+flags, which would define more fields, who knows. It's probable
the presence of that field is necessary for some players, so it had to be
present in the first place.

-- 
Clément B.
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