[FFmpeg-user] Two SAR/DAR pairs (codec and stream SAR/DAR)

Carl Eugen Hoyos cehoyos at ag.or.at
Thu Dec 3 15:19:34 CET 2015

On Tuesday 01 December 2015 09:32:14 am Tobias Rapp wrote:
> > I coundn’t find what is codec SAR, and why it differs from streams SAR.
> > Could you explain it for me?

SAR - sample aspect ratio or pixel aspect ratio

It can differ for several reasons including bugs in the recording software.

> Some video codecs allow to store the aspect ratio within the binary data
> chunk of each encoded frame. Also some container formats allow to store
> the aspect ratio globally for the whole stream (file). Now when both
> values exist they possibly contain mismatching information. Which value
> is the correct one is not obvious, I guess media players have some own
> guessing algorithm to decide which one to use.

It makes sense to use the container aspect ratio if they disagree.

Carl Eugen

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