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

Carl Eugen Hoyos cehoyos at ag.or.at
Wed Jan 15 00:22:22 CET 2014

Rio Kierkels <riokierkels <at> gmail.com> writes:

> The way I think ffmpeg uses DAR and SAR on decode (and 
> this is where I base all my other code around ffmpeg on)
> is that when you have a typical anamorphic DV source 
> which is 720x576 on disk but has a display aspect ratio 
> of 16:9 it first unsqueezes the footage until the 
> resolution reaches the DAR target of 16:9. In this case 
> that would be 1024x576. Then it applies all it's magic 
> to that frame size and on ouput if the output display 
> aspect ratio is equivalent of the current frame aspect 
> ratio it will set the DAR to 1.

To the best of my knowledge, this is not what FFmpeg does 
by default.
On the contrary, it will be default not change the 
resolution (which is 720x576 in your example).

Carl Eugen

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