The following is a series of steps for poly BPM. The first two series are currently possible. The proposed idea is the last one.
00 Using Renoise Tools (It-Alien’s Beat Slicer and dBlue’s Slices to Pattern)
01 render empty selection to sample_1 at original BPM
02 select where in the pattern you’d like to start with new BPM
03 go to sample_1, select the position that matches step 2’s starting point and highlight this all the way to end. you may also mark this starting point
04 copy the matching highlight to new instrument_2
05 at sample_2, use It-Alien’s Beat Slicer, where you have options to auto mark in number of slices, seconds or BPM
06 select and auto mark new BPM, or slices, or seconds. later if you don’t like it, you can always make new slice mark’s with sample_2
07 go to sample_1, highlight the beggining to the starting point at step 3
08 copy and paste on the beggining of sample_2
09 there should be a highlight of this paste, hit the right key to maintain location and mark it
10 mark the beggining of sample_2
11 adjust sample_2 to sync pattern length
12 use dBlue’s Slices to Pattern
00 Rendering (this one is much much simpler)
01 render selection to sample or disk (audio sample with original bpm)
02 change bpm
03 render selection to sample or disk (different audio sample with new bpm)
04 playback at original BPM if you like
00 Proposed Idea
01 select pattern data: note, pan, vol, delay
02 adjust pattern data to new bpm
