Script for macOS to save and restore audio input/output device and volume settings

volumetoggle.rb

#!/usr/bin/env ruby
# frozen_string_literal: true

# Brett Terpstra <https://brettterpstra.com>
#
# macOS: Stores all input/output devices and volume settings to a
# text file, restores on demand
#
## Dependencies
# SwitchAudioSource <https://github.com/deweller/switchaudio-osx>
# Install with Homebrew: `brew install switchaudio-osx`
#
## Usage:
#   volumetoggle.rb save
#   volumetoggle.rb restore

require 'yaml'
TYPE_OUTPUT = 'output'
TYPE_INPUT = 'input'
TYPE_SYSTEM = 'system'
STORE_FILE = File.expand_path('~/.saved_volume')
SWITCH_AUDIO = '/usr/local/bin/SwitchAudioSource'

def get_device(type)
  `#{SWITCH_AUDIO} -c -t #{type}`.strip
end

def set_device(type, device)
  `#{SWITCH_AUDIO} -t #{type} -s "#{device}"`
end

def set_volume(type, volume, muted = nil)
  script = "set volume #{type} volume #{volume}"
  if type == TYPE_OUTPUT
    script += " #{(muted ? ' with' : ' without')} output muted"
  end
  `osascript -e "#{script}"`
end

# String helpers
class String
  def to_literal
    case self
    when /\d+/
      to_i
    when /true/
      true
    when /false/
      false
    when /missing value/
      nil
    end
  end

  def to_literal!
    replace to_literal
  end

  def to_h
    output = {}
    split(/, /).each do |item|
      parts = item.split(/:/)[0..1]
      k = parts[0] =~ /muted/ ? 'muted' : parts[0].sub(/ volume/, '')
      k = k.to_sym
      v = parts[1].to_literal
      output[k] = v
    end
    output
  end
end

case ARGV[0]
when /save/
  devices = {}
  devices[:input] = get_device(TYPE_INPUT)
  devices[:output] = get_device(TYPE_OUTPUT)
  devices[:system] = get_device(TYPE_SYSTEM)
  settings = `osascript -e 'return (get volume settings)'`.strip.to_h

  settings[:devices] = devices
  File.open(STORE_FILE, 'w') do |f|
    f.puts YAML.dump(settings)
  end
  warn "Settings written to #{STORE_FILE}"
when /restore/
  raise "No store file found at #{STORE_FILE}" unless File.exist?(STORE_FILE)

  settings = YAML.load(IO.read(STORE_FILE))

  settings[:devices].each { |k, v| set_device(k.to_s, v) }

  %i[output input alert].each do |sym|
    set_volume(sym.to_s, settings[sym], settings[:muted]) if settings[sym]
  end
  warn 'Settings restored'
  warn YAML.dump settings
else
  warn 'Requires argument'
  warn "#{File.basename(__FILE__)} save or #{File.basename(__FILE__)} save"
  Process.exit 1
end