[FFmpeg-devel] [PATCH] telecine filter

Derek Buitenhuis derek.buitenhuis at gmail.com
Mon Apr 8 20:10:18 CEST 2013

On 2013-04-08 1:58 PM, Paul B Mahol wrote:
>>> + at item pattern
>>> +String representing for how many fields a frame is to be displayed.
>>> +The default value is @code{23}.
>>> + at end table
>> This is a woefully inadequate explanation. Not only does it not explain
>> the format the string should be it, it breaks from the standard ordering
>> convention (which is calling it, e.g. "3:2 Pulldown" ). Examples are not
>> a substitute for an actual explanation.
>> Also, it is a grammatically invalid English sentence.
> I will need hand for this because I'm not that guy to write valid English
> sentence in this case.

"A string of numbers representing the pulldown pattern you wish to apply.
 The default value is @code{23}."

As for why 23 is used instead of the normal notation of 32, I guess only
the original plugin authors knows that. Maybe he just wanted to be special.

>>> +        tc->frame[nout]->pts = AV_NOPTS_VALUE;
>> This seems broken behavior at best.
> Yes, that why there is TODO, note that there is no perfect solution
> possible with current lavfi API.
> (FYI original code does not have this issue)
> So I need fedback in that area.

For CFR content, it's pretty simple: calculate then new framerate and
generate PTS from it.

For VFR content, the only thing I can think of is to set the time base to
some multiple of what it used to be (calculated from the pattern), in order
to use finer grained PTS (since there are new frames now). But yeah, this
is ugly. On the other hand, if you are trying to apply telecine to VFR
content, you're likely insane anyway.

- Derek

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