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

[Andrew Randrianasulu]

чт, 29 мая 2025 г., 01:38 Mark Filipak <markfilipak.imdb at gmail.com>:

> On 28/05/2025 18.15, Paul B Mahol wrote:
> > On Wed, May 28, 2025 at 9:35 PM Mark Filipak <markfilipak.imdb at gmail.com
> >
> > wrote:
> >
> >> On 28/05/2025 17.27, Paul B Mahol wrote:
> >>> On Wed, May 28, 2025 at 9:19 PM Mark Filipak <
> markfilipak.imdb at gmail.com
> >>>
> >>> wrote:
> >>>
> >>>> On 28/05/2025 15.39, Alex Xu wrote:
> >>>>> 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.
> >>>>
> >>>> Yes, there are 'strange' telecines. I've seen 'NTSC' field sequences
> in
> >>>> which authors inserted
> >>>> varying telecined sequences at varying times (when bad timing became
> >>>> obvious to them) to maintain
> >>>> running time and sync with audio, and even 'PAL' that took cinema to
> 25
> >>>> fps via varying telecine,
> >>>> again to maintain running time and audio sync. I gave up trying to
> make
> >>>> them 24p in the usual ways
> >>>> and simply 'bobbed' them at 59.940p and 50p.
> >>>>
> >>>> None of those experiences justify keeping the 'detelecine' filter.
> >>>>
> >>>> I'm simply using 'detelecine' as a clear-cut example of all the
> filters
> >>>> that should be deprecated,
> >>>> or at least marked "obsolete". That would really help novices avoid
> >>>> headaches.
> >>>>
> >>>>
> >>> But user above just reported only single usecase where detelecine just
> >>> works for him.
> >>
> >> That's not what Alex wrote. Alex wrote "got strange results with the
> >> `fieldmatch+decimate` combo" --
> >> which I proceeded to explain. He didn't claim that 'detelecine' works.
> In
> >> addition,
> >> 'fieldmatch'+'decimate' can be configured to match the static
> >> functionality of 'detelecine', and
> >> such static matching to a deprecated filter should be included in the
> >> documentation, as an aid.
> >>
> >> The alternative is to continue emasculating FFmpeg.
> >>
> >
> > Your futile and toxic attempts are in vain.
>
> Thanks for your opinion, Paul. Your desire to distract from real issues is
> well known to us.
>
> > Detelecine filter is for fixed patterns, other filters try to guess
> pattern
> > by some heuristic which might be correct only in 99.9% cases.
>
> Yes, for static patterns, which 'fieldmatch' can also do.
>
> > Detelecine filter is just an attempt for inverse of telecine filter. And
> as
> > such its primary objective is testing.
>
> An attempt, you say? It's for testing, you say? Gee, I don't remember
> reading that in the
> documentation. Wasting the valuable word "detelecine" on a test filter is
> a shame, wouldn't you say?
>

Generally I prefer to have two versions of similar things, so when one
broke at least I have plan B or some easy way to compare them.




> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
> To unsubscribe, visit link above, or email
> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".
>