[FFmpeg-user] Confusion about fieldmatch, decimate and framerate
Carl Eugen Hoyos
cehoyos at ag.or.at
Fri Nov 8 04:06:10 CET 2013
Nicholas Robbins <nickrobbins <at> yahoo.com> writes:
> > > Uploaded to upload.ffmpeg.org/incoming as
> > sample-robbins.mkv
> > The sample claims to be 60fps while it actually is 30fps.
> > Assuming you produced the mkv file from a MPEG original:
> > Is the problem also reproducible with the original mpeg
> > file?
> So I get the original file using mplayer's dumpstream.
Could you provide that sample?
I am not saying there is much difference, but reporting a
problem with the original sample is generally slightly
better (I will open a report).
Some random additional comments:
The decimate filter is "stupid", it will produce a cfr
output that depends on the fps of the input, the filter
can only work for cfr input with correct frame rate.
You can get this input by using the fps filter first,
since your sample is (apparently) really 30fps cfr, the
fps filter neither drops nor duplicates frames, it only
adjusts the frame rate.
I originally suggested "fps=30000/1001" and "r 24000/1001"
but it appears to me the sample is actually 30fps (and
not 29.9), so better values (if the sample is longer than
one minute) may be "fps=30" and "r 24".
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