[Csnd-dev] UDO local sr

This is mainly for Victor Lazzarini,

I saw you added code in a PR to implement local sample rate in UDOs which I
think is absolutely fantastic.
It seems there are two limitations that I really hope could be addressed in
the future:
1. The code allows for upsampling but not for downsampling
2. The code does not allow for a-rate opcodes

The use case I am hoping will be possible in the future is when having a
reasonably high global sr (say 48kHz or even 96kHz) where I would like to
apply relatively narrow band filters with center frequencies at say 20Hz,
25Hz 32Hz or the like. Such filters tend to be somewhat unstable at such
high SR if they also need to be reasonably steep, and by downsampling
before filtering a better result is often achieved. This is commonly done
in signal processing for analysis in e.g. Matlab or GNU octave.
The idea is e.g. to be able to manipulate individual bands, like in the pvs
group of opcodes, and combining the individual bands back to one signal
afterwords, so just docking global reduction of SR would not be a viable
route, unless of course starting several instances of csound and using
channel opcodes to combine everything in the end.

Would this be a possibility in some future iteration of the newly
implemented code?

Regards,
Anders