Squeezing 12/8 MIDI into 4/4 song

I have a song which was recorded in 4/4 but is essentially in 12/8, ie. all the beats are subdivided into 3. However I now have a MIDI drum track that was recorded in a 12/8 project that I want to paste in, and getting them to align is difficult.

The problem is that to do this, the conversion from 12/8 to 4/4 requires that I scale the length and starting positions by 66.6%, because I'm going from measures with 12 eighth notes to measures with 8 eighth notes. Sonar provides a function to scale MIDI length, but only lets me enter a whole number for the percentage. So, the nearest I can use is 67%, and that has noticeable error even at the end of a 4-measure clip, never mind across the whole song.

Is there a way of getting the precise ratio I need? Or some other combination of length adjustments I can perform that will approximate 66.666666% closely enough? The best I've found so far is to scale up by 833% and then down by 8% which gives 66.64%, which isn't bad! (Maybe this will be useful to someone even if I don't get a better answer.)

Kylotan

The problem is that to do this, the conversion from 12/8 to 4/4 requires that I scale the length and starting positions by 66.6%, because I'm going from measures with 12 eighth notes to measures with 8 eighth notes. Sonar provides a function to scale MIDI length, but only lets me enter a whole number for the percentage. So, the nearest I can use is 67%, and that has noticeable error even at the end of a 4-measure clip, never mind across the whole song.

If you can only get the timing approximate, you could then quantize.  You will need to set the "snap to" in PRV to 8th triplets.

Unfortunately not, because the MIDI is from a purchased pack which I'd not be allowed to share except once inside the finished song. I did manage to get it working well enough by using the ratio in my first post, re-aligning the start of individual sections to the beginning of the nearest measure, and quantising to 16th triplets (probably could have used 8th triplets.

It is an interesting issue though because I would have thought a 12/8 to 4/4 conversion is one of the more common use cases for changing a MIDI file's length. (I do it the other way around too, for example where I have MIDI in 4/4 triplets that I need in 12/8, but that's easy as I can just multiply by 150%.) Yet it can't easily be done. Even just letting the dialogue box take a decimal point would have helped as 66.66% would be good enough. Anyone know if X1 has anything like this, or should I file a suggestion (somewhere)?