[FFmpeg-user] ffmpeg architecture question #2

[pdr0]

Carl Eugen Hoyos-2 wrote
>> Am 24.04.2020 um 11:10 schrieb Mark Filipak <

> markfilipak.windows+ffmpeg@

> >:
>> 
>> I've been told that, for soft telecined video the decoder is fully
>> compliant and therefore outputs 30fps
> 
> (“fps” is highly ambiguous in this sentence.)
> 
> This is not correct.
> I believe I told you some time ago that this is not how the decoder
> behaves. I believe such a behaviour would not make sense for FFmpeg
> (because you cannot connect FFmpeg’s output to an NTSC CRT). The telecine
> filter would not work at all if above were the case.
> Or in other words: FFmpeg outputs approximately 24 frames per second for
> typical soft-telecined program streams.
> 
> The only thing FFmpeg does to be “compliant” is to forward the correct
> time base.


If you use direct encode, no filters, no switches, the output from soft
telecine input video is 29.97p, where every 5th frame is a duplicate

e.g
ffmpeg -i input.mpeg -c:v rawvideo -an output.yuv

But you can "force" it to output 23.976p by using -vf fps

Is this what you mean by "forward the correct time base" ?



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