AVI 8fps > 24fps

ConvertFPS(24) will work and every frame should appear three times in a row. Just a warning that the playback would be jerky and not very smooth so do this only if you have to. Just a note that 24 fps is not DVD compatible, so after the conversion make sure it's 25 or 23.976 fps (with pulldown of course, use AssumeFPS()). in this case you should also change the length of the audio.

Convertfps will blend adjacent frames to create the new ones and you can go directly to 23.976 or 25fps if you use that. If you want duplicates you should use SelectEvery(1,0,0,0).AssumeFPS(23.976) instead.

Why not just ChangeFPS(23.976)? Xesdeeni