[FFmpeg-devel] [PATCHv3] lavf: add av_guess_frame_sample_aspect_ratio function

Michael Niedermayer michaelni at gmx.at
Sat May 12 21:09:46 CEST 2012

On Sat, May 12, 2012 at 09:06:04PM +0200, Marton Balint wrote:
> On Tue, 8 May 2012, Marton Balint wrote:
> >
> >On Tue, 8 May 2012, Joakim Plate wrote:
> >
> >>On Mon, May 7, 2012 at 11:03 PM, Michael Niedermayer
> >><michaelni at gmx.at> wrote:
> >>>On Mon, May 07, 2012 at 08:39:32PM +0200, Joakim Plate wrote:
> >>>>Just thought i'd chime in here. We (xbmc) ended up using that special
> >>>>handling of stream aspect being 1:1 and codec aspect not being 1:1 to
> >>>>solve a few samples we found in the wild. Thing the where mp4's
> >>>>recorded by some camera if i remember correctly. So i'm sort of in
> >>>>favor of that solution even if it's ugly.
> >>>
> >>>iam in favor of whatever works best and is simple
> >>>
> >>>in that sense, does anyone know how common in the wild files are that
> >>>change the sample aspect ratio midstream but have a valid and not 1:1
> >>>sample aspect at the format level ?
> >>
> >>Can't really say.
> >>
> >>Here our our ticket and change for this. Seems it was an MKV after allH
> >>so maybe i should just have asked him to re-mux the file.
> >>https://github.com/xbmc/xbmc/commit/f08c8f01d1014a7f161d40a7cc8ede0680f9fe77
> >>http://trac.xbmc.org/ticket/12187
> >>
> >>And now that i look at it I notice the commit message is wrong. It's
> >>the opposite order of what it does (what it does matches what was
> >>proposed here).
> >
> >You don't need the 1:1 hack to fix the file in this bug, because
> >here the stream sample aspect ratio is 4:3 (DAR is 16:9),
> >therefore it got priority over the codec sample aspect ratio
> >anyway.
> >
> >So the reason for keeping the 1:1 hack was probably some other
> >file which is not in the report.
> >
> >Anyway, I really agree with Reimar here and rather not handle 1:1
> >aspect specially. If we do find a device (camera, etc.) which sets
> >these fields to wrong values, then I think it is better to match
> >for some identification of the creator device in the file if it is
> >possible and handle _that_ specially.
> Is there anybody who is against the v3 patch for some reason? If no

> objections come in a day or two, then Michael, can you apply it?

sure just send me a reminder in a day or 2 otherwise i will forget

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