[FFmpeg-user] Why are PTS values different from what's expected?

pdr0 pdr0 at shaw.ca
Thu Apr 1 20:40:22 EEST 2021

Mark Filipak (ffmpeg) wrote
> What I'm trying to do is make a 120000/1001fps cfr in which each frame is
> a proportionally weighted 
> pixel mix of the 24 picture-per-second original:
> I'm sure it would be way better than standard telecine -- zero judder --
> and I'm pretty sure it 
> would be so close to motion vector interpolation that any difference would
> be imperceptible. I'm 
> also sure that it would be a much faster process than mvinterpolate. The
> only question would be 
> resulting file size (though I think they would be very close).

Is this 120000/1001 CFR intended for a 60Hz display? Do you decimate by 2 to
make it 60000/1001 after ?

"proportionally weighted pixel mix" it sounds like a standard frame blended
conversion . eg. You drop a 23.976p asset on a 120000/1001fps timeline in a
NLE and enable frame blending. Or in avisynth it would be

This zip file example has the original 24000/1001, weighted frame blending
to 120000/1001, and decimation to 60000/1001 - is this something close to
what you had in mind ?

The "textbook" fps conversion categories are 1) duplicates 2) blends 3)
optical flow (such as minterpolate) . Each has various pros/cons

For what you are considering (blends), the frames will be "evenly spaced" in
time - technically less judder -  but there will be "strobing" and blurry
loss of quality (frame blending). Every 5th frame is an "original" frame,
original quality that "snaps" into view. What some people do to reduce that
is offset the timing (resample all frames, instead of keeping every 5th
original), to reduce that jarring effect; same with optical flow - resample
all frames instead of keeping T=0.0 (shift to T=0.1)

The "best" is to get a 120Hz/300Hz judder free display :) And if you're in
that group that likes motion interpolation,  a motion interpolation display

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