[Cin] DAR, PAR and SAR, again

[Andrew Randrianasulu]

сб, 20 янв. 2024 г., 01:10 Terje J. Hanssen via Cin <
cin at lists.cinelerra-gg.org>:

>
>
> Den 19.01.2024 22:58, skrev Andrea paz:
> > Well, I would say that I just don't understand how CinGG works!
> > I was wrong in thinking that since Info-->Detail provided the same
> > information as ffmpeg, then CinGG and ffmpeg worked the same way with
> > non-square pixels. Instead we return to Raffaella Traniello's guide:
> > the definitions of PAR=pixel aspecrt ratio; SAR=Storage aspect ratio;
> > and DAR=display aspect ratio apply. And consequently the PAR=DAR/SAR
> > formula applies, and so does the wikipedia table.
> > However without knowing how to read the code of CinGG I am not able to
> > understand anything. I think I will sleep on it now...
> > My apologize.
>
> Maybe a reason is that FFmpeg became implementet (heavily) in Cinelerra
> by GG version 4.6mod or was it 5.0?
>
> But I want to ask Andrew here: How do the Set Format Presets take care
> of SAR, because selecting one I can't see it, or is it behind the scene
> somewhere?
>

Behind the scene in ffmpeg.C

you can set SAR on encoding by going into ffmpeg parameters, it will be
there as just aspect. We know DAR from preset, we can calculate Pixel
Aspect Ratio themselves, and thus SAR ( I did this in recent  bluray
patches).


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