How to convert 20 fps OGM file to MPEG-2?

[digicube]

I have an OGM file which I extracted the video(XVID), audio(OGG) and subtitle file(SRT). The video and audio is 20 fps. Is there a way to convert it to 23.976 fps and keeping the audio and subtitle in sync?
I used AVISYNTH with assumefps(23.976, true) since this is what I used to convert 25 fps to 23.976 fps, but it made the 20 fps video shorter/faster. I used besweet to change the fps from 20 to 23.976 which resulted in the chipmunk effect; the audio became faster.
I'm using CCE to encode to MPEG-2.

[BlackAdder]

A few years back I found a trick to do this with some AVI files I had. The trick is that 20fps is really a 3:2 pulldown from 25. I used TMPGenc, but the principal could be adapted to any encoder. Also, I'm sure that this trick could be improved upon, so don't be afraid to experiment.

For the audio use BeSweet to change it from 25 FPS to 23.976 FPS.



Here's the text from a post I wrote about it. The original post is HERE :

I encode to 23.976 from 20 fps with the described method and the results are much better then letting TMPGenc do the frame rate conversion. It's not perfect, but it's watchable. I've also updated the AVISynth script:

#PULLDOWN
AVISource("e:\test.avi")
BicubicResize(352,576)
AssumeFrameBased
SeparateFields
SelectEvery(8, 0,1, 2,3,2, 5,4, 7,6,7)
Weave
#At this point your AVI will be 25fps.
#Uncomment the next line to slow the avi down to 23.976
#AssumeFPS(23.976)
# END of script

Open the script in Virtual Dub and add a 2:1 Verticle reduction filter. This will bring the video back down to 352x288. Believe it or not this helps to reduce interlace lines in the final mpeg. Basically, just double the height of your source avi for the BicubicResize in the script, do the 2:1 V-reduction in Vdub, and then crop if needed. Then frameserve out to TMPGenc.

[digicube]

AssumeFrameBased
SeparateFields
SelectEvery(8, 0,1, 2,3,2, 5,4, 7,6,7)
Weave
#At this point your AVI will be 25fps.
AssumeFPS(23.976)

Cool this one works, the video and audio are in synch although the original 23 min video became 24 min now but I don't really notice much of a slow down.

[digicube]

ChangeFPS is an easier and better method, I think. The result MPEG-2 has the same duration as the 20fps original video.

[BlackAdder]

Does the audio stay in synch with ChangeFPS? Is there any jerkiness?

As for the change in time, this is normal.. This is how films (23.976 FPS) are converted to PAL (25 FPS). They just speed it up and bit and no one notices the differences. That's why IMDB will have slighly different run times for North American and English (as in England) movie run times.

[thor300]

ConvertFPS is the best in my opinion. ChangeFps is good too, but works slightly different. Have a look at http://www.avisynth.org/index.php?page=FPS

Both will keep the original file's duration, so the audio can be converted as normal without any change in pitch and lenght.