THINK 320k mp3s are better than 96k mp3? TAKE THE BIT RATE CHALLENGE. On your commandline.

abtester.rb

# THINK 320k mp3s are better than 96k mp3?
# TAKE THE BIT RATE CHALLENGE!

# Needs ruby, ffmpeg and mplayer on your commandline.
# Some sample flac files can be found at:
#  http://www.eclassical.com/pages/24-bit-faq.html
#  http://www.2l.no/hires/
#  http://www.findhdmusic.com/high-res-audio/free-music/

# LICENSE: This scripe is released under Public Domain.

require 'io/console'
puts "-----\nanilg's bit-rate busting script!\n-----"
if ARGV.length == 0
  puts "Usage: ruby abtester.rb <flacfile>"
  puts "       ruby abtester.rb <flacfile> <runs> <sampleseconds>"
  puts "  (needs ffmpeg and mplayer installed)"
  puts "----"
  exit
end

def randstr len = 8
  key_space = [('a'..'z'), ('0'..'9')].map { |i| i.to_a }.flatten
  pass = (0...len).map { key_space[rand(key_space.length)] }.join
  return pass
end

runs = ARGV[1] && ARGV[1].to_i || 10 # 10 runs default
sample = ARGV[2] && ARGV[2].to_i || 10 # 10 seconds default

if runs <=4
  puts "\n** WARNING: #{runs} runs is too few to be definitive. (minimum 8 recommended) **\n\n"
end

r1 = "320k"
r2 = "96k"

v1 = "tmp"+randstr(5)
v2 = "tmp"+randstr(5)

puts "Working with flac file #{ARGV[0]}"
puts "  cleaning up older files"
`rm -f tmp* 2>&1 > /dev/null`
puts "  building #{r1} version.."
`ffmpeg -loglevel panic -i '#{ARGV[0]}' -ab #{r1} -acodec libmp3lame #{v1}.mp3`
puts "  ..done"
puts "  building #{r2} version.."
`ffmpeg -loglevel panic -i '#{ARGV[0]}' -ab #{r2} -acodec libmp3lame #{v2}.mp3`
puts "  ..done"

# play

puts "\n\nLet the games begin!\nWe will now play a random section from both bitrates, and you can choose which was 'better'.\nReady? Press key.."
STDIN.getch

# set random order for 10 runs, and a random point to play music from
data = {}
runs.times.map{|i| data[i] = [v1, v2].shuffle + [(rand*90).to_i]}

currentrun = 0

while currentrun < runs do
  puts "\n-----\nRUN #{currentrun+1}/#{runs}"
  puts "  playing 'a'"; sleep 1
  `mplayer -ss 00:00:#{data[currentrun][2]} -endpos 00:00:#{sample}  #{data[currentrun][0]}.mp3 2>&1 >/dev/null`
  puts "  playing 'b'"; sleep 1
  `mplayer -ss 00:00:#{data[currentrun][2]} -endpos 00:00:#{sample}  #{data[currentrun][1]}.mp3 2>&1 >/dev/null`
  puts "  which was better? [a] , [b] , [r]eplay"
  k = STDIN.getch
  if k == "a"
    data[currentrun].push("a")
    puts "..marked " + k
    currentrun += 1
  elsif k == "b"
    data[currentrun].push("b")
    puts " ..marked " + k
    currentrun += 1
  end
end

# Build report
puts "\n#{'='*15}\nREPORT\n#{'='*15}"
puts "#{r1} is #{v1}.mp3"
puts "#{r2} is #{v2}.mp3"
report = data.keys.map{|i|
  r = data[i]
  reverse = (r[0] == v2)
  s1 = reverse ? "#{r1}, #{r2}": "#{r2}, #{r1}"
  if r[3] == "a"
    s2 = (reverse ? "#{r2}": "#{r1}")
  else
    s2 = (reverse ? "#{r1}": "#{r2}")
  end
  "[RUN #{i+1}/#{runs}] Presented: " + s1 + ". You picked " + s2
}

puts "-----"
puts report.join("\n") + "\n#{'='*15}"
puts "So how close were you? ;) Spread the word, and this gist!\n\n"