[MEncoder-users] 23.976 --> 25 fps conversion problem

[Tamas Selmeci]

Hi all!

My task is to convert any incoming .AVI video into a well-defined 
format: AVI container, Xvid encoder, 25 fps @ 1800 kbps video, MP3 @ 
48000 Hz, 128 kbps.

Everything seemed to work fine until I've received a recent movie with 
an fps value of 23.976. What mencoder does is just duplicating the last 
frame after every 24 frames, thus producing a 25 fps output file. But in 
case of a bit more action in the scene, the viewer will realize a small 
"stop" in the movie flow and it destroys the "movie experience".

With the correct mixture/selection of noskip, -mc 0, etc. I was able to 
make mencoder not duplicating the last frame after each 24 frames, but 
then the A/V sync broke. Obviously, the sound was arriving much later, 
since a 23.976 fps video was played at 25 fps.

According to Wikipedia, telecine/pullup methods are for solving these 
problems for the case e.g. 23.976 fps --> 30 fps. In the case of mine 25 
fps is fixed, can not be changed at all.

Is there any way I can produce 25 fps movie output from 23.976 fps 
material with frame interpolation/appropriate telecine/pullup? -vf 
pullup did not solve my problem. That annoying "stop" in movie flow must 
not be present at all.

(My rescue idea is to recode video at 25 fps without frame duplication, 
thus the movie duration will decrease by ~4% [23.976/25], and the audio 
is resampled at a 4% higher frequency to keep A/V sync)

Thanks in advance!
-- 
Selmeci, Tamas
http://www.open-st.eu