mkv_to_mp4.rb

#!/usr/bin/env ruby
require 'fileutils'
raise 'please input mkv' unless ARGV[0] =~ /\.mkv$/

ARGV.select{|x| x =~ /\.mkv$/ }.each{|x|
  mp4 = x.sub(/\.mkv$/, 'mp4')
  info = `mkvmerge --identify "#{x}"`.split("\n")
  video_id = info.select{|s| s =~ /video/}.first.split(' ')[1].to_i
  audio_id = info.select{|s| s =~ /audio/}.first.split(' ')[1].to_i
  system 'mkvextract', 'tracks', x, "#{video_id}:vid.h264", "#{audio_id}:audio.aac"
  system 'MP4Box', '-add', "vid.h264", '-add', 'audio.aac', '-new', mp4
  FileUtils.rm 'vid.h264'
  FileUtils.rm 'audio.aac'
}