ffmpeg_ipod_touch.rb

mp3 = false

input = ARGV.shift
while input =~ /^-/
  case input
  when /^-mp3/
    mp3 = true
  end
  input = ARGV.shift
end

vcodec = nil
width = nil
height = nil
acodec = nil
ar = nil
ac = nil
ab = nil

info = `ffmpeg -i '#{input}' 2>&1 | grep Stream`
exit 1 if $? != 0

info.each_line {|line|
  case line
  when /Video:\s+([^,]+),\s+([^,]+),\s+(\d+)x(\d+),\ ([\.\d]+)/
    # Stream #0.0: Video: vp6f, yuv420p, 512x384, 30.83 tb(r)
    vcodec = $1
    width = $3.to_i
    height = $4.to_i
  when /Audio:\s+([^,]+),\s+(\d+)\s+Hz,\s+([^,]+),\s+([^,]+),\s+(\d+)\s+kb\/s/
    # Stream #0.1: Audio: mp3, 44100 Hz, stereo, s16, 128 kb/s
    acodec = $1
    ar = $2.to_i
    ac = ($3 == 'stereo') ? 2 : 1
    ab = $5.to_i
  end
}

padtop = nil
padbottom = nil
padleft = nil
padright = nil

new_width = 480
new_height = (height*(new_width/width.to_f)).to_i
if new_height > 320
  new_height = 320
  new_width = (width*(new_height/height.to_f)).to_i
  padleft = (480 - new_width)/2
  padleft -= 1 unless padleft % 2 == 0
  padright = 480 - new_width - padleft
else
  padtop = (480 - new_height)/2
  padtop -= 1 unless padleft % 2 == 0
  padbottom = 480 - new_height - padtop
end

opts = ['-i', input]

# format
opts << '-f'
opts << (mp3 ? 'mp3' : 'mp4')

# video
if mp3
  opts << '-vn'
else
  # vcodec
  opts << '-vcodec'
  opts << 'libx264'

  # size
  opts << '-s'
  opts << "#{new_width}x#{new_height}"

  # padding
  opts += ['-padtop', padtop.to_s] if padtop
  opts += ['-padbottom', padbottom.to_s] if padbottom
  opts += ['-padleft', padleft.to_s] if padleft
  opts += ['-padright', padright.to_s] if padright
end

# audio
if mp3
  opts << '-acodec'
  if acodec == 'mp3'
    opts << 'copy'
  else
    opts << 'libmp3lame'
  end
else
  opts << '-acodec'
  opts << 'libfaac'
end

output = input.sub(/\.[^\.]+$/, mp3 ? '.mp3' : '.mp4')
opts << output

system('ffmpeg', *opts)