[FFmpeg-user] Detelecine: I got the right result from the wrong command?

[Alex Xu]

Whoops, looks like I got cut off, the above command still has same issue of
duplicated frames 174+175 and skipped 173

On Wed, May 28, 2025 at 4:18 PM Alex Xu <alexkurosakimh3 at gmail.com> wrote:

> When I said, "doesn't matter" I meant that the issue of duplicated frames
> 174+175 and skipped 173. Yes, I understand that incorrectly specifying the
> fps can cause other issues though.
>
> Anyways, I tried:
>
> ffmpeg -i detelecine_input.mkv -vf
> "fieldmatch,decimate,drawtext=fontfile=Arial.ttf: text='%{frame_num}':
> start_number=0: x=(w-tw)/2: y=h-(2*lh): fontcolor=black: fontsize=20:
> box=1: boxcolor=white: boxborderw=5" -c:v libx264 -crf 18 -c:a aac -b:a
> 192k -pix_fmt yuv420p fieldmatch_decimate_only_no_r.mkv
>
> the issue of duplicated frames 174+175 and skipped 173.
>
> In case you missed it, my test file was in the first message of the chain.
> And using the detelecine filter got me the right result (with wrong params?)
>
> On Wed, May 28, 2025 at 3:54 PM Mark Filipak <markfilipak.imdb at gmail.com>
> wrote:
>
>> On 28/05/2025 18.46, Alex Xu wrote:
>> > I put it there since it was in Huspnet's original command.
>>
>> Ahem!
>>
>> > I don't think it
>> > matters,
>>
>> Of course it matters. You're taking 30/1.001fps, detelecining to
>> 24/1.001fps, then telling FFmpeg to
>> make 24fps from it. Of course, every 1000th frame is repeated.
>>
>> > same problem occurs if I omit it or use -r 24000/1001 instead.
>>
>> I think you must be fuddled.
>>
>> Your command should be
>> ffmpeg -i <input> -vf fieldmatch,decimate -map 0 -c <encoder> <output>
>>
>>
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>