Two-in/Stereo-out: simplified support for separate mixer channels for a user's instrument and microphone

[seanogdelaney]

Already possible, but awkward (run two jamulus clients, on platforms where that's possible).
To simplify for users, we can implement it directly (one client).

Proposal:
Client-only code change.
Mixer shows an independent, duplicate fader with name suffix "Mic" and vocal icon.

PR to follow.

• Implements a narrow subset of Multi Channel Fader on one Jamulus #96.
• Related to Allow mono input device and channel selection for stereo input devices. #2344.

[pljones]

So...

Would the two-in client have two jitter buffers at the server, one of each channel? I guess it would need to be at that point.

Each of those jitter buffers would take up two slots on the server -- essentially to every other user, the same as if you'd run two clients.

Would you want each of the two channels to have a separate profile? How would anyone identify between them on the mixer?

The simpler approach remains running separate Jamulus instances using a virtual audio cable if needed.