[theora-dev] ffmpeg2theora aspect ratio

Stefan Bender oraqhf at gmx.net
Sun Dec 6 08:17:36 PST 2009


On 2009-12-05 21:32:52 wrote Lino Mastrodomenico:
> 2009/12/4 Stefan Bender <oraqhf at gmx.net>:
> > FWIW, it didn't change any encoding parameters;
> > it just prevented e.g. mplayer to automatically scale 720x576
> > theora content to the correct 768x576 (for 4:3 frame aspect)
> Sorry for nitpicking, but the 4:3 or 16:9 aspect for PAL content isn't
> for the whole 720x576 frame: it's the aspect ratio of the 702x576
> active area. Which means that the overall aspect ratio for PAL frames
> is 160:117 (for "4:3" content) or 640:351 (for "16:9" movies).
> I.e. they should played at approximately 788x576 or 1050x576
> respectively (not 768x576 or 1024x576 as most software players do).

No problem, I didn't know about that.
Actually, some of the saved dvb streams I have are already 704x576.

However, the piece of code in question was like an arbitrary
restriction on the pixel aspect ratio (values smaller than 1.09
were set to 1.0), unrelated to the input or output sizes.

It would be a nice feature to be able to set the pixel aspect ratio
from the command line.

> A complete guide to all this aspect ratio madness is:
>     http://lipas.uwasa.fi/~f76998/video/conversion/

Thanks for the link, quite useful to know.


More information about the theora-dev mailing list