[FFmpeg-user] tinterlace broken - SAR & DAR wrong

[Paul B Mahol]

On Mon, Jan 4, 2021 at 9:21 PM Mark Filipak (ffmpeg) <markfilipak at bog.us>
wrote:

> On 01/04/2021 02:45 PM, pdr0 wrote:
> > Mark Filipak (ffmpeg) wrote
> >>
> >> You wrote: "What's wrong with using setsar filter after tinterlace?"
> >>
> >> I tried that from the git-go. I just reran it.
> >>
> >> ffmpeg -report -i "source 720x480 [SAR 8x9 DAR 4x3] 29.97 fps.VOB"
> >> -filter_complex "separatefields,
> >> shuffleframes=0 1 2 4 3 6 5 7 8 9, split[Ain][Bin],
> >>
> [Ain]select=not(eq(mod(n\,10)\,2)+eq(mod(n\,10)\,3)+eq(mod(n\,10)\,6)+eq(mod(n\,10)\,7))[Aout],
> >>
> [Bin]select=eq(mod(n\,10)\,2)+eq(mod(n\,10)\,3)+eq(mod(n\,10)\,6)+eq(mod(n\,10)\,7),
> >> tinterlace,
> >> setsar=sar=8/9, bwdif=mode=send_field:deint=all, decimate=cycle=2[Bout],
> >> [Aout][Bout]interleave,
> >> tinterlace, setsar=sar=8/9, bwdif=mode=send_frame:deint=interlaced"
> >> -codec:a copy -codec:s copy -dn
> >> output.mkv
> >>
> >> Putting setsar after tinterlace doesn't work. I did investigate that
> but I
> >> can't recall why -- I
> >> think it's because DAR is then wrong. The report is below.
> >
> >
> > You can't interleave images with different dimensions
> >
> > Aout has separated fields, to 720x240 , but Bout is 720x480
>
> [Bout] is 720x240: I'm using 'mode=send_field' in 'bwdif=mode=send_field',
> and the following
> 'decimate' doesn't change that. The problem is that 'tinterleave' is
> marking the output as "SAR =
> 16:9" instead of "8:9" (which is what it should be and should never be
> changed).
>
> SAR cannot change unless DAR/PAR changes (which it doesn't). Look:
>
> SAR = DAR/PAR = (8:3)/(720:240) = (8:3)/(6:2) = 8:9
> SAR = DAR/PAR = (4:3)/(720:480) = (4:3)/(3:2) = 8:9
>
> The current tinterlace filter is setting SAR = 16:9. That is just plain
> wrong.
>

That is just invalid statement.


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