[FFmpeg-devel] [PATCH] Fix sample_aspect_ratio computation for stereo matroska content.

Aaron Colwell acolwell at google.com
Thu Nov 26 01:40:09 CET 2015

On Tue, Nov 24, 2015 at 10:43 AM Kirill Gavrilov <gavr.mail at gmail.com>

> On Mon, Nov 23, 2015 at 11:37 PM, Aaron Colwell <acolwell at google.com>
> wrote:
> > matroskaenc.c applies divisors to the display width/height when
> generating
> > stereo content. This patch adds the corresponding multipliers to
> > matroskadec.c
> > so that the original sample aspect ratio can be recovered.
> Just to link this patch with Matroska Specification notes:
> http://www.matroska.org/technical/specs/notes.html#3D
> > The pixel count of the track (PixelWidth/PixelHeight) should be the raw
> > amount of pixels (for example 3840x1080 for full HD side by side)
> > and the DisplayWidth/Height in pixels should be the amount of pixels for
> > one plane (1920x1080 for that full HD stream).
> >

Is this intended to be a call to action or are you just adding information
to this particular thread? I'd like to get the change reviewed so I can
determine whether I need to make any other changes.

This change basically allows 'ffmpeg -i blah.mkv foo.mkv ; ffprobe foo.mkv'
to show that foo.mkv has the same SAR and DAR as blah.mkv when blah.mkv
contains stereo content. Without this patch the SAR & DAR get smaller based
on whichever dimension is halved by the stereo layout.

Hope this helps,

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