I have some problems when running shell-fm and another application using Alsa. Scenarios tried:
1.) Start shell-fm and play a song. Start VLC. A message appears:
Audio output failed:
The audio device "default" could not be used:
Device or resource busy.
2.) Start shell-fm and play a song. Run aplay and similar message appears:
ALSA lib pcm_dmix.c:1018:(snd_pcm_dmix_open) unable to open slave
aplay: main:682: audio open error: Device or resource busy
3.) Start VLC and play a movie. Start shell-fm. A different message appears:
ao_alsa WARNING: Unable to open surround playback. Trying default device...
This does seem like Alsa problem, however the issue only occurs when shell-fm is running. I can play aplay, youtube and vlc altogether without any problems.