[FFmpeg-devel] Scale filter bug

Michael Niedermayer michaelni at gmx.at
Fri Dec 9 21:12:58 CET 2011

On Fri, Dec 09, 2011 at 08:01:26PM +0500, Alexander Bokovikov wrote:
> Hi, All,
> The scale filer being applied to produce M4V or MP4 file format
> inserts wrong pixel aspect ratio box, and incorrectly sets the frame
> size in the track header box. As a result target aspect ratio is the
> same as source file aspect ratio, though I've defined target width
> and height explicitly. The same effect appears if I use -s WxH
> parameter instead of -vf scale=W:H one.
> As I believe the problem is here:
> [SAR 25:36 DAR 5:3]
> instead of
> [SAR 1:1 DAR 12:5]
> Changing the values by manual boxes editing I get correct movie.
> I.e. the problem isn't in a wrong stream encoding, but just in wrong
> MP4 boxes writing. Taking into account that 12:5 = (36x5)/(25x3)
> (see digits above), I believe the bug is in these calculations -
> wrong digits are at wrong places. Something like that.
> Here is the source FLV file:
> http://home.bokovikov.com/ffmpeg/video5.flv

wget http://home.bokovikov.com/ffmpeg/video5.flv
--2011-12-09 21:09:11--  http://home.bokovikov.com/ffmpeg/video5.flv
Resolving home.bokovikov.com...
Connecting to home.bokovikov.com||:80... connected.
HTTP request sent, awaiting response... 404 Not Found
2011-12-09 21:09:12 ERROR 404: Not Found.

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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