I think a derivative of the feedback endpoint patches just made it into the mainline 5.14 release, but not the volume controls.
That sounds very interesting.
I'm now looking for a way to build a virtual USB class compliant audio device with 8 input and 8 output channels for the sole purpose of providing audio loopback (Ch1 in is directly connected to Ch1 out, Ch2 in to Ch2 out etc.).
This might not make much sense using with a modern desktop DAW but it would make a huge difference when used with iPhones and iPads for music production because iOS lacks virtual audio ports and the sandboxed architecture won't allow 3rd party developers to build something like that.
I have a class compliant 8in, 8out USB audio interface here if that helps in any way (tracing USB communication maybe?) but I have no idea how to start with my Pi Zero W, which would be my device of choice because it's small and efficient.
Ideally, the Pi Zero W would plug into the USB port or Camera Connection Kit of the iPhone/iPad and show up as a class compliant audio interface with 8 ins and 8 outs so these can be used to route audio between different audio apps (synths, DAWs, effects...)
Any hints would be very welcome!
I've been searching for a solution like this for quite a while but I haven't found anything promising so far.
Thank you.