@spacelordmother thanks, that was exactly what I was looking for. It does a similar thing as pd's [line~], interpolates between two values over time at k-rate.
I did like this now. Basically it lets you play samples with the encoder in the way you do it with a CD-DJ controller. Maybe it helps someone else. If you have any suggestions to improve or simplify it please tell me.
The hardest parts was (and still is) to get an idea of the fixed point number computation and all the different value ranges ranges. Before I only used puredata which uses floating point computation and you don't have to worry about anything. This made me a little mad in the beginning, but now I think it all has its deeper purpose and I'm learning something new about bit-shifting and computer math.
Now some serious advertisement ...groupie talk ... or resume ... (converted right after the first day really using it!)
I think as a high quality tool for (interactive) audio installations the axoloti totaly wins.
There are so many clever things about it and it has a very good workflow i.e. ...
- voltage monitor (which showed me that mý usb cable was too long)
- file manager (which is slow, but still useful)
- shrinkable board with allot of solder pads (I additionally had to desolder the 6.3mm jacks and the USB connector)
- very goop object browser and active community
- fixed grid in the patch editor (no more "snap-to-grid/clean-up" function that does not work like in pd)
- ultra fast compilation and live mode with displays and buttons/dials (missing all this was a pain with patchblocks, and made me sell and never use them again)
Before I would have used a raspberry + puredata, which also works great if you have an i2c soundcard and all the right settings. But setup takes long and the when using gpios and raspberry specific things which can't run on the pc the workflow is very bad (patch on pc, ssh, stop all running scripts/pd-patches, copy new patch, restart all scripts/pd_patches ... and again ...).
I can even run the axoloti on 18650 lipo cells and so have very good, mobile, controllable audio-stuff.