[FFmpeg-user] sntsc

[Devin Heitmueller]

On Mon, Dec 25, 2023 at 4:04 AM Mark Filipak <markfilipak.imdb at gmail.com>
wrote:

> On 12/22/23 16:09, Devin Heitmueller wrote:
> > On Fri, Dec 22, 2023 at 3:57 PM Mark Filipak <markfilipak.imdb at gmail.com>
> wrote:
> >> On 12/22/23 15:14, Devin Heitmueller wrote:
> >>> On Fri, Dec 22, 2023 at 2:38 PM Mark Filipak <
> markfilipak.imdb at gmail.com> wrote:
> >>>> This page: https://ffmpeg.org/ffmpeg-utils.html
> >>>> 'says' this:
> >>>>
> >>>> "The following abbreviations are recognized:
> >>>> "‘sntsc’
> >>>> "    640x480"
> >>>>
> >>>> What is it? I'm not aware that any such thing exists.
> >>>
> >>> It's NTSC with square pixels...
> >>
> >> How do you go from 720x480 to 640x480 without throwing away 80 pixels
> per line?
> >> Normally, 720x480 decodes to 720x540.
> -snip-
> >
> > Even worse, you can have 720x480 video with a display aspect ratio of
> > 16:9 (i.e. standard definition widescreen).  In this case the pixel
> > aspect ratio is going to be 40:33.
>
> Huh? "720x480 video with a display aspect ratio of 16:9" is what's on most
> 'NTSC' DVDs. The PAR is
> 32/27.
>
>
Is that what you calculated the PAR to be?  Or is that what "ffmpeg -i"
says when run against the VOB?

DVDs in general are a pretty poor reference as to what constitutes
"correct", given there are so many different authoring tools that were used
and many of them were poor quality.  That said, I haven't reviewed the
underlying DVD specs, so perhaps they put in there some sort of clause
where widescreen encodings should be 720x480 with explicitly no overscan
region.

Devin

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