[FFmpeg-user] Aspect Ratios: DAR, SAR and Frame Size

[Rio Kierkels]

I think the ffmpeg command internally applies the SAR and DAR variables and
transforms the resolution until SAR is 1:1 and DAR matches the resolution
aspect ratio when it decodes the source footage. This way the math
internally is easier. On output it will recompute them according to your
given scale settings and other settings that could influence the aspect
ratios.
Still if you really want a good answer you should supply example input and
output files.

I have a small test dpx sequence that I often use. If you guy's like I can
put it on an ftp server somewhere.




On 13 January 2014 16:11, Adi Shavit <adishavit at gmail.com> wrote:

> Hi Rio,
>
>   Thanks for the prompt reply.
>
> the DAR and SAR are applied on playback by the player you use. 352x240 are
> > the actual pixels stored in the file.
> >
>
> This basically answers my last question.
>
>
> > By default ffmpeg stretches you image to the dimensions you specify, no
> > padding or cropping is done. <snip>
>
>
>
>
> If I understand what you say, then if I didn't specify any special
> dimensions, then ffmpeg will not do any stretching?
>
> But, if DAR and SAR are applied only on playback (by any respectable
> player), wouldn't they be applied by *ffmpeg itself *when encoding to a new
> file format or, say, when saving frames as JPGs?
>
> Thanks,
> Adi
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