[MEncoder-users] inverse telecine with 60 fps progressive video

Scott W. Larson scowl at pacifier.com
Sat Apr 9 08:16:06 CEST 2005

D Richard Felker III wrote:

>Even a 2:3 pattern is extremely choppy..
The 2:3 pattern makes 24 fps material look perfect at 60 frames per 
second. I've never seen film look this smooth outside of a movie theater.

>Never set -fps manually; mencoder knows the input fps. 
At least it wasn't hurting anything.

>Also, the
>numbers are 60000/1001 and 24000/1001, NOT 59.97 and 23.967.
Of course I meant to type 23.976. This value is suggested three times in 
the mencoder documentation. The documentation doesn't suggest 24000/1001 
anywhere. It doesn't even mention that -ofps accepts this fractional 

>Notice the word fields. If the output is still progressive, I call it
>framerate conversion by frame duplication, not pulldown. But this is
>getting into silly semantics.
Companies that transfer film to 720p still call them "telecine pulldown 
conversions" and treat them no differently from their other services 
that produce interlaced conversions. One popular 60 progressive fps HD 
camera says it uses a "telecine 2:3 pulldown" process to optionally 
convert its output to 24 fps. The term pulldown doesn't necessarily 
imply interlaced video any more now that progressive video formats (480p 
and 720p) are becoming more popular to convert to.

>>Well, it would be great if there were a filter that could lock onto the
>>2:3 progressive pattern. I wonder if decimate could just remove all the
>>duplicate frames leaving 24 fps output.
>Possibly, with the right settings. You need to adjust the thresholds
>so it doesn't drop too much or too little.
I'm half way through a conversion using decimate with no tuning. 
Everything I've reviewed so far looks absolutely perfect! No choppiness, 
no duplicates, exactly what I wanted. Thanks for steering me away from 
trying to use pulldown filters. It would have taken me months to figure 
out they weren't really doing anything.

I also put tinterlace=1 in front of decimate to throw away half the 
frames. It's faster since decimate has less work to do.

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