Testing, from a script, if audio devices are in silent?

Question

Is there a default program where I can check if my audio devices are in silent?

Edit: By silence, I mean that if there is something playing on that (not just activated or opened)

Something like this:

if [[ device0 is silent ]] ; then
    radio $RANDOM
fi

Edit 2: What I'm trying to achieve is a script that plays radio and can keep playing when the player fails, e.g. if the internet connection goes down and the player didn't recovery, I will kill the player and start over again

Answer 1

If you're using PulseAudio (Gnome-based Linux distributions tend to use PulseAudio, you can check if one is running with ps -C pulseaudio) and you want to know whether some applications are sending any data to any "sink", you could do:

pacmd list-sink-inputs | grep -c 'state: RUNNING'

Still with PulseAudio, if you want to check whether your sound output is muted, there might be simpler but you can get the "mute" status of the default "sink" using:

pacmd dump | awk '
  $1 == "set-sink-mute" {m[$2] = $3}
  $1 == "set-default-sink" {s = $2}
  END {print m[s]}'

Answer 2

If I understand you right, here an example:

Silence:

fuser /dev/snd/timer && echo "Something is playing" || echo "There's silence"
There's silence

I turn on audacious:

fuser /dev/snd/timer && echo "Something is playing" || echo "There's silence"
/dev/snd/timer:      47663
Something is playing

For OSS chande /dev/snd/timer to /dev/dsp.

This is a very dependent method.

Answer 3

Assuming you are using ALSA mixer for your sound, you can use amixer to query information about audio devices. An audio device typically has several audio channels - or controls - each which can be muted and unmuted. For example to check if the Master control is muted you would do something like:

if amixer get Master | grep -q off; then
    # action
fi

Use the set option to perform things on the controls. See man amixer for more help.

Answer 4

htor's answer will probably work, but it is entirely possible that "off" will appear somewhere else in the output, causing an incorrect result. Here is a more strict check using GNU awk:

if amixer get Master | gawk 'END{ if ( $NF != "[off]" ) { exit 1 } }'; then
    # muted
else
    # unmuted
fi