Rake task to prepare MP3 files for Apple's HTTP Streaming protocol and upload them to S3

audio.rake

namespace :audio do
  desc "downsample, segment, and upload audio files"
  task :load => :environment do
    access_key_id = ENV['AWS_ACCESS_KEY_ID']
    secret_access_key = ENV['AWS_ACCESS_KEY']
    source_dir = ENV['SOURCE_DIR']

    fail "Must specify AWS_ACCESS_KEY_ID, AWS_ACCESS_KEY, and SOURCE_DIR" if access_key_id.blank? || secret_access_key.blank? || source_dir.blank?
    filenames = Dir["#{source_dir}/**/**.*"]
    fail "#{source_dir} is empty" if filenames.empty?

    require "shellwords"
    require 'cgi'

    today = Date.today.to_s
    dest_dir = "#{Rails.root}/tmp"
    s3_dest = "files.example.com/audio"
    prog_urls = []
    mp3_paths = []

    filenames.each do |filename|
      new_filename = File.basename(filename.gsub('\s-\s','-').gsub(/\s+/,'-'),".mp3")
      subdir = "#{today}/#{new_filename}"
      dir = "#{dest_dir}/#{subdir}"
      FileUtils.mkdir_p(dir)
      complete_file = "#{dir}/#{new_filename}.mp3"

      cmd = "ffmpeg -i '#{filename}' -ab 64k -acodec libmp3lame '#{complete_file}'"
      system cmd

      cmd = "/usr/bin/mediafilesegmenter -f #{dir} #{Shellwords.escape(complete_file)}"
      system cmd
      prog_urls << "http://#{s3_dest}/#{subdir}/prog_index.m3u8"
      mp3_paths << "#{subdir}/#{CGI.escape(File.basename(complete_file))}"
    end

    cmd = "s3cmd put -H -M --progress --recursive --acl-public #{dest_dir}/#{today} s3://#{s3_dest}/ 2>&1"
    system(cmd)

    prog_urls.each do |url|
      cmd = "mediastreamvalidator validate #{url} 2>&1"
      system cmd
    end
  end
end