PulseAudio Solo Mode

pa_solo_mode.sh

#!/bin/sh

SLEEP_TIME=0.1

print_help() {
cat << EOF
This script can be used to run any shell command so that it's the only
process that can play sounds using PulseAudio. It continuously mutes all the
new streams that are not connected to the command passed as argument. Once
muted, it won't be managed by this script anymore (so that it will stay
unmuted if you want)

A typical use-case scenario is video-calling, when you want to avoid that
other apps unexpectedly play sounds (e.g. various websites do this)

Syntax: 
  $0 [-r regex] [-h] <yourcommand -with --yours --options>

Options:
  -r :  allows the usage of an awk regex; instead of non-muting children
        processes, patterns that match the regex will be not muted; this
        is useful for processes that internally use nohup or similar methods,
        spawining processes that are not children. E.g.
          $0 -r skype skypeforlinux

  -h :  show this help

Usage:
Just run the command. To exit, use ctrl+c.

EOF
}

get_stream_pid_list() {
  pactl list sink-inputs | awk '
    /application.process.id/ {
      gsub("\"", "", $3)
      print $3
    }'
}

get_stream_index_from_pid() {
  pid=$1
  pactl list sink-inputs | awk '
    /^Sink Input #[0-9]+$/ {
      sub("#", "", $3)
      x=$3
    } 
    /application.process.id = "'"$pid"'"/ {
      print x
    }'
}

daemon_mute_except() {
  except_pid=$1
  regex=$2
  echo "Muting all streams except $except_pid and its children!"
  already_toggled=""
  old_stream_list=""
  while true; do
    stream_list=$(get_stream_pid_list)
    if test "$stream_list" == "$old_stream_list":
    then
      continue
      sleep $SLEEP_TIME
    fi

    if test -z "$regex"
    then
      # get the target pid's children
      children=$(pstree "$except_pid" -p)
    else
      # if there is a regex, get the processes matching the regex
      children=$(pstree -ap | awk "/.*${regex}.*/{print}")
    fi
    children=$(echo "$children" | awk -v FPAT='([0-9]+)' '{$1=$1;print}')

    for pid in $stream_list; do
      case "$children" in
        *${pid}*)
          # this is the target pid or a child
          continue
          sleep $SLEEP_TIME
          ;;
      esac
      case "$already_toggled" in
        *${pid}*)
          # this pid was already toggled
          continue
          sleep $SLEEP_TIME
          ;;
      esac
      # mute the stream
      index=$(get_stream_index_from_pid "$pid")
      echo "Muting stream index $index"
      pactl set-sink-input-mute "$index" 1
      already_toggled="$already_toggled:$pid"
    done

    old_stream_list=$stream_list
    sleep $SLEEP_TIME
  done
}

# run our command and take its PID
option=$1
case "$option" in
  "-r")
    regex=$2
    shift 2
    ;;
  "-h")
    print_help
    exit
    ;;
  "")
    print_help
    exit
    ;;
  *) 
    regex=""
    ;;
esac

echo "Running command" "$@"
"$@" &
except_pid=$!
# start the daemon: continuously mute streams
daemon_mute_except $except_pid "$regex"