This is a first cut at this to evaluate buffer size adjustments on
supported platforms. A final version might limit status bar reports to
>1000 dropped frames or similar.
This enforces an audio input device in the settings dialog since we
can't do anything without an input device. A nil audio output device
is allowed with a warning.
Adjusting these may help with audio drop-outs, particularly on slower
CPU systems or heavily loaded systems. Smaller buffer sizes leave less
margin for process interruptions, larger sizes waste resources that
could impact other processes.