Ruby snippet for reencoding .mp4 videos using ffmpeg

ffmpeg_reencode.rb

# Returns the file path with extension removed
def strip_extension(filepath)
  File.join(
    File.dirname(filepath),
    File.basename(filepath, File.extname(filepath))
  )
end

# Re-encodes the given file as .mp4 using libh264 and MP3 audio. Returns the
# filename of the new file.
def convert_video(filename)
  new_name = strip_extension(filename) + ".mp4"
  puts "Will convert #{filename} -> #{new_name}"
  cmd = [
    "ffmpeg",
    "-y",
    "-i",
    filename,
    "-map_metadata",
    "0",
    "-movflags",
    "use_metadata_tags",
    "-c:v",
    "libx264",
    "-preset",
    "medium",
    "-crf",
    "22",
    "-c:a",
    "libmp3lame",
    "-q:a",
    "1",
    new_name,
  ]
  output = ""
  IO.popen(cmd, "r", :err=>[:child, :out]) do |cmd_output|
    output = cmd_output.read
  end
  puts "Conversion done; last 3 lines of stdout:"
  puts output.split(/\n+/)[-3..].join("\n")
  new_name
end