Proper method changing FPS from 59.94p > 29.970p???

59.94 progressive? I'd leave that as it is.

Given that you want an output frame rate of exactly half the input I would just write 'ChangeFPS("NTSC_Video")' in the AVISynth script. Do this before other filters (unless it's a bob deinterlacer or something else that changes the amount of frames) otherwise you will waste time processing twice as many frames as you need to only to throw half of them away. If for some reason (I can't think of any) that doesn't work 'SelectEven()', 'SelectOdd()' or 'Decimate(2)' would also give you the output frame rate you want. ConvertFPS() isnt ideal as it blends adjacent frames, wasting time processing and creating a 'ghosted' output picture. It is only useful (debatably) if you arn't dividing the frame rate by a multiple of 2, for example going from 29.970fps (NTSC Video) to 25fps (PAL) Ben

thx guys I appreciate the replies:)

Another quick question on this topic...How does halving the frame-rate like this effect my audio? Will it remain in-sync or do I need to re-encode it changing the audio frame-rate as well?

All the methods mentioned above (ChangeFPS, ConvertFPS, SelectEven, SelectOdd) preserve the clip running-time, so audio stays in sync (assuming it was in sync to start with).