PaperclipMp3

Paperclip Mp3 is a Paperclip post-processor that convert to mp3 file of the audio attachment .

has_attached_file :sound,
      styles: {
              mp3: {
                      format: :mp3,
                      :convert_options => {:ar => '44100', :ac => '2', :ab => '192000'},
                      :processors => [:mp3]
              }
      }