symptom:
- no audio in some applications.
- pulseaudio only shows a dummy audio output channel.
$ pulseaudio -k
$ pulseaudio -D
E: [pulseaudio] main.c: Daemon startup failed.
Check if there is any application blocking the output sound card:
$ fuser -v /dev/snd/pcm*
USER PID ACCESS COMMAND
/dev/snd/pcmC0D0c: overshoot 4454 F...m Application
/dev/snd/pcmC2D0c: overshoot 12878 F...m pulseaudio
Quit or kill that application and try again.
