[HELP] Slow down by 4%

[Miranda]

I have a 29.97 interlaced NTSC MKV file which has been standards converted from PAL (it's from a DVD). As it was originally shot on film, it should have been slowed down from its original PAL speed of 25fps by 4%.

I guess I need to do QTGMC to 23.976, and at the same time slow it down from its original 25fps speed whilst retaining the 23.976 frame rate. Is this possible? Or should I first QTGMC to 25fps, and then do a conform to 23.976?

[Selur]

I don't really know the characteristics of the source or what you are aiming to archive, but here we go:

I have a 29.97 interlaced NTSC MKV file which has been standards converted from PAL (it's from a DVD).

There are so many ways to convert between NTSC and PAL,.. (for amusement check out https://forum.doom9.org/showthread.php?t=176104 and read the translation of Scharfis_Brain "Exotic Interlacing")

I guess I need to do QTGMC to 23.976

Not possible. QTGMC does deinterlacing, not IVTC (= inversed telecine, which converts 29.97 telecined back to 23.976 progressive content).

and at the same time slow it down from its original 25fps speed whilst retaining the 23.976 frame rate

What? I don't get it.

Knowing that your source was created through a norm conversion between PAL and NTSC probably only is interesting if you want to undo the conversion.

If your source is 29.97 interlaced (!not telecined!) and you want to convert to 23.976 (which will destroy tons of motion information), I would recommend to QTGMC-Bob and then use sRestore to get to 23.976.
If your source is 29.97 telecined (!not interlaced!) and you want to convert to 23.976, simple use some IVTC method.

(You could also always deinterlace and then speed up / slow down the video, but that would also require doing the same with the audio.)

Cu Selur