[FFmpeg-user] ffmpeg architecture question #2

Carl Eugen Hoyos ceffmpeg at gmail.com
Fri Apr 24 22:35:37 EEST 2020

> Am 24.04.2020 um 19:34 schrieb pdr0 <pdr0 at shaw.ca>:
> 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

(Consider to test with other output formats.)

> But you can "force" it to output 23.976p by using -vf fps
> Is this what you mean by "forward the correct time base" ?


Carl Eugen 

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