Hi there,

I was wondering whether it's possible to relax the constraints of the data callback closure of Stream to not be Sync.

What I'm trying to do at the moment is to prepare audio processors on the main thread before the audio stream starts, then move them into the audio stream's data callback so that they can be used to process audio input/output. With the data callback closure constrained to Sync, I was only able to use structures that are Sync themselves in the audio processors. (For example, it won't work for the resamplers from https://github.com/HEnquist/rubato).

I took a bit closer look into the mechanism of the audio stream, and I think it might be ok to relax the constraint to only require Send for the data callback - at least for the limited use cases I can think of, though I might be missing something.

Keen to hear your thoughts. Cheers.