[FFmpeg-user] ffmpeg architecture question #2

pdr0 pdr0 at shaw.ca
Fri Apr 24 20:28:24 EEST 2020

Mark Filipak wrote
>> I've been told that, for soft telecined video
>>  the decoder is fully compliant and therefore outputs 30fps
>> I've also been told that the 30fps is interlaced (which I found
>> surprising)
>> Is this correct so far?


If you take a soft telecine input, encode it directly to rawvideo or
lossless output, you can confirm this. 
The output is 29.97 (interlaced content) . 

> When I do 'telecine=pattern=5', I wind up with this
> |<--------------------------1/6s-------------------------->|
> [A/a_][A/a_][A/b_][B/b_][B/b_][C/c_][C/c_][C/d_][D/d_][D/d_] 55-telecine
> I have confirmed it by single-frame stepping through test videos.


Pattern looks correct, but unless you are doing something differently , your
timescale is not correct

When input is vob, mpeg2-ps or mpeg-es using soft telecine in my test, using
telecine=pattern=5 the output frame rate is 74.925 as expected  (2.5 * 29.97
= 74.925). This mean RF flags are used, 29.97i output from decoder. Since
its 74.925fps, the scale in your diagram for 1/6s is wrong for

Both ffplay and mpv look like they ignore the repeat field flags, the
preview is progressive 23.976p

Sent from: http://www.ffmpeg-archive.org/

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