Mute Spotify ads on OS X

spotify_mute_ads.rb

# coding: utf-8
#!/usr/bin/env ruby
#
# Mutes Spotify ads by monitoring Growl's output in syslog, and changing the
# system-wide audio output to dummy output when an ad is detected.
#
# == Installation
#
# 1. Install Soundflower (http://code.google.com/p/soundflower/)
# 2. Run the following command in your home directory, or wherever you prefer.
#    curl -L -O http://gisthead.heroku.com/350200/spotify_ads_mute.rb && ruby spotify_mute_ads.rb
#
# NOTE: Everything except installation of Soundflower is done automatically,
#       but I've left all the steps here for the sake of clarity.
#       All you have to do is install Soundflower and run this script.
#
# Requires Soundflower and SwitchAudioSource utility for switching audio to dummy output
# http://code.google.com/p/soundflower/
# http://switchaudio-osx.googlecode.com/files/SwitchAudioSource-v1.0.zip
#
# Make Growl log to syslog:
#
# defaults write com.Growl.GrowlHelperApp GrowlLoggingEnabled -int 1
# sudo killall GrowlHelperApp
#
# Restart GrowlHelperApp with one of the following:
#
# open ~/Library/PreferencePanes/Growl.prefPane/Contents/Resources/GrowlHelperApp.app
# open /Library/PreferencePanes/Growl.prefPane/Contents/Resources/GrowlHelperApp.app
#
# Run the script.
#

PATH_TO_AUDIO_SWITCHER = "#{ENV['HOME']}/SwitchAudioSource"
NORMAL_OUTPUT_DEVICE   = "Built-in Output"
DUMMY_OUTPUT_DEVICE    = "Soundflower (2ch)"

AD_MATCHERS = ["spotify:track:", "spotify:album:", /https?:\/\//]

def sh cmd
  puts cmd; system cmd
end

###
# Setup
#
unless File.exist? PATH_TO_AUDIO_SWITCHER
  puts "SwitchAudioSource not found at #{PATH_TO_AUDIO_SWITCHER}, fetching and unzipping…"

  sh 'curl -o /tmp/sas.zip http://switchaudio-osx.googlecode.com/files/SwitchAudioSource-v1.0.zip'
  sh 'cd /tmp; unzip -o sas.zip; mv SwitchAudioSource ~/SwitchAudioSource'
end

growl_logging = %x[defaults read com.Growl.GrowlHelperApp GrowlLoggingEnabled].to_i

if growl_logging.zero?
  sh 'defaults write com.Growl.GrowlHelperApp GrowlLoggingEnabled -int 1'
  sh 'sudo killall GrowlHelperApp'
  sh 'open ~/Library/PreferencePanes/Growl.prefPane/Contents/Resources/GrowlHelperApp.app'
  sh 'open /Library/PreferencePanes/Growl.prefPane/Contents/Resources/GrowlHelperApp.app'
end

unless `#{PATH_TO_AUDIO_SWITCHER} -a` =~ /Soundflower \(2ch\)/
  sh "#{PATH_TO_AUDIO_SWITCHER} -a"
  puts
  puts "Soundflower output device not found. Is Soundflower installed?"
  exit
end

###

def set_output_device(device)
  `#{PATH_TO_AUDIO_SWITCHER} -t output -s '#{device}'`
end

def is_ad?(string)
  string =~ Regexp.union(*AD_MATCHERS)
end

def spotify_log
  IO.popen("syslog -F '$(Message)' -w 1 -E none -d") do |f|
    while line = f.gets
      # Spotify GrowlHelper messages are split in two lines
      if line =~ /^Spotify:/
        buffer = line.tr("\n", ' ')
      else
        if buffer
          buffer << line.chomp
          yield(buffer)
          buffer = nil
        end
      end
    end
  end
end

spotify_log do |line|
  puts line

  if is_ad? line
    set_output_device(DUMMY_OUTPUT_DEVICE)
  else
    set_output_device(NORMAL_OUTPUT_DEVICE)
  end
end