[FFmpeg-user] Why does the 'detelecine' filter exist?

[Alex Xu]

I recently used the detelecine command in this thread:
https://ffmpeg.org/pipermail/ffmpeg-user/2025-May/059249.html

I got strange results with the `fieldmatch+decimate` combo, where decimate
wasn't removing the correct frame.

I also got strange results with the `pullup` filter.

This may just be because my sample file was really exotic though.

But yea, there's a lot of different ways to detelecine. It was confusing
trying them all. But detelecine is supposedly the dumbest and simplest.

I suspect detelecine has some bugs, trying a `telecine` filter on a 23.976 fps
video and then applying a `detelecine` filter on a video doesn't give a
correct result for me, all with default params.

On Wed, May 28, 2025 at 12:10 PM Paul B Mahol <onemda at gmail.com> wrote:

> On Wed, May 28, 2025 at 7:07 PM Mark Filipak <markfilipak.imdb at gmail.com>
> wrote:
>
> > On 28/05/2025 15.04, Paul B Mahol wrote:
> > > On Wed, May 28, 2025 at 7:00 PM Mark Filipak <
> markfilipak.imdb at gmail.com
> > >
> > > wrote:
> > >
> > >> Why does the 'detelecine' filter exist? It is weak and clumsy.
> > >>
> > >> The 'fieldmatch' filter followed by 'decimate' do a better job and are
> > >> robust.
> > >>
> > >> By continuing to carry obsolete filters, FFmpeg emasculates itself.
> That
> > >> makes FFmpeg appear to be
> > >> chaotic and ties up names that could be, should be reused to better
> > effect.
> > >>
> > >> The same could be written about many FFmpeg filters. Dump them, or
> > create
> > >> a "Legacy" category in the
> > >> documentation and put them there. Also, include documentation in
> > "Legacy"
> > >> that shows how to replace
> > >> the obsolete filters in existing scripts. Promote the best filters,
> not
> > >> the worst.
> > >>
> > >
> > > You are extremely biased and unhelpful.
> >
> > Paul, do you _ever_ use 'detelecine'?
> >
>
> Nope.
>
>
> >
> > > What other filters you want to purge and why?
> >
> > Shall we, together, begin a list?
> >
>
> Just you, please!
>
>
> >
> >
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