- The toolbar's Mic: on / off (red while on) turns the microphone on and off while recording;
its state is saved as microphone in [video] for the next recording. A microphone that cannot
be opened turns it off again, with a toast saying why.
- modules/Screen_Record: record_set_microphone, record_microphone, record_microphone_failed. The
audio thread opens the microphone only while it is on (so Windows shows it in use only then)
and closes it when turned off. Record_Options.audio_track gives the MP4 a sound track whatever
is on at the start, silent while nothing is, as one cannot be added once the header is
written; the app always asks for it. The sources heard and the failures are kept as they
happen, not only at the start.
- record-probe -mic-toggle: the microphone on at 3 s and off at 7 s. With system sound and with
nothing else on, the track runs the whole recording without a break.