cpal VS rubato

There is a cross-platform audio library for Rust: cpal https://github.com/rustaudio/cpal

I had to do something similar to this a while back. I used cpal.

Working on a live performance software that would let our band have live real-time practices over the internet. Top priority is minimum latency, so I'm trying to hook it up through ASIO. Not much luck yet. I've tried cpal, but I've run into numerous known random bugs (and some versions don't compile for me). At least I confirmed that I can push the audio through a TCP socket successfully.

you need to use a "loopback" device, as shown here - https://github.com/RustAudio/cpal/pull/478 (note, ive only tested this on windows - if its not supported on linux you could always plug your sound card output into its line-in/mic jack)

Regarding improving the API for 0.6, something that bugs me about the current Rust audio ecosystem is that everyone is reinventing the wheel with their own audio buffer types each with their own API that downstream users have to learn. This makes it more of a hassle to pass audio data from one library to another than it should be. I've been contributing to the audio crate which provides buffer structs and traits for working with audio buffers with a common API regardless of their layout in memory. I have a work-in-progress branch for Rubato refactoring it to use the audio crate, though there's a bit more work to do in the audio crate to complete that. Would you be interested in using the audio crate in Symphonia?

If you want to change tempo and pitch together, that's resampling. You can use Rubato's asynchronous resamplers for that.