Upload a WAV file with Paperclip and store both .wav and .mp3 versions

I have a Rails application where people can use an in browser sound editor to create wav files and upload them t开发者_运维技巧o the server.

I use Paperclip for handling the sound file upload.

I would like to be able to convert the wav file to an mp3, but keep both files.

I have read about Paperclip processors, but I'm not sure how to use them to get both files instead of just converting to mp3 only.

Ok, this probably isn't optimal but it works pretty well. I ended up adding another attachment to my Sound class for the mp3, and added a before_validation filter to hook into it. In addition, since I had some existing wav attachments, I created a reconvert_to_mp3 method to handle the migrating of the existing records.

has_attached_file :mp3,
  :storage => :s3,
  :s3_credentials => "#{RAILS_ROOT}/config/s3.yml",
  :path => "sounds/:id/:style.:extension"

before_validation :convert_to_mp3

def reconvert_to_mp3
  wavfile = Tempfile.new(".wav")
  wavfile.binmode

  open(wav.url) do |f|
    wavfile << f.read
  end

  wavfile.close

  convert_tempfile(wavfile)
end

def convert_to_mp3
  tempfile = wav.queued_for_write[:original]

  unless tempfile.nil?
    convert_tempfile(tempfile)
  end
end

def convert_tempfile(tempfile)
  dst = Tempfile.new(".mp3")

  cmd_args = [File.expand_path(tempfile.path), File.expand_path(dst.path)]
  system("lame", *cmd_args)

  dst.binmode
  io = StringIO.new(dst.read)
  dst.close

  io.original_filename = "sound.mp3"
  io.content_type = "audio/mpeg"

  self.mp3 = io
end