Converting 25 fps PAL back to the original 24 fps

In my quest to find all the different versions of the SW saga, I found that some are only in 25 fps PAL or 30 fps NTSC. NTSC preserves the running time but not the original 24 fps. PAL preserves the frames. I've tried a few things with no luck. I just need to know how to convert it and keep all the frames. Also how to do it without too many conversion steps.

I usually deinterlace it if necessary and then I do AssumeFPS(23.976) in Avisynth, but no idea if it's an "optimal" method, it's just fast and delivers acceptable results for me. If you want to start with an NTSC source you need to do an inverse telecine

Danfun128 said:

And as for the reverse (24 fps to original 25 fps)?

You mean a 25fps TV source released on Blu-Ray at 23.976 like some BBC stuff, or what?

AssumeFPS("pal_video",sync_audio=true).SSRC(48000)

-or-

AssumeFPS(25,1,sync_audio=true).ResampleAudio(48000)

[-or- etc.]

If the audio was pitch-corrected when it was converted from the original 25fps to "24"fps, you will need to correct it again as part of your conversion back. Unfortunately every pitch correction step introduces unavoidable and unrecoverable artifacts.