[FFmpeg-user] Misson, impossible?, Prescaling, a, video...

[meino.cramer at gmx.de]

Roger Pack <rogerdpack2 at gmail.com> [12-10-27 02:11]:
> > The video I want to play does not have square pixels...(I think
> > this is called "anamorphic"???) and normally is scaled to have
> > square pixels while playing ... if hardware acceleration is available.
> > If this is done on my embedded system with software scaling I count
> > the frames while drinking coffee.... ;)
> 
> http://ffmpeg.org/pipermail/ffmpeg-user/2011-November/003203.html
> may be related
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Hi Roger,

...THATS helping! 

Yes, now it converts to square pixels...

Only one question remains:

When scaling to the size of the LCD screen of my embedded Linux board,
which is 800x480 pixels, I either can do a 

 -vf scale=iw*sar:ih,scale=800:-1

or a 

 -vf scale=iw*sar:ih,scale=-1:480

depending on the input: If one will result in a size replacing the -1
whcih exceeds the size of the corresponding axis of the LCD I have to
chosse the other one....

Would be nice, if ffmpeg could determine this by itself...but how?

Best regards,
mcc