code.delx.au - transcoding/blob - fix-pal-speedup

   1 #!/bin/bash -e
   2
   3 # Many DVDs released in Australia are sped up from 24fps to 25fps.
   4 # This script reverses the procedure, correcting the audio pitch.
   5 # The video framerate is adjusted without re-encoding. The audio is slowed and
   6 # normalised then re-encoded as mp3.
   7
   8 if [ -z "$1" -o -z "$2" ]; then
   9         echo "Usage: $0 destdir infile"
  10         exit 1
  11 fi
  12
  13 FORCEFPS="24"
  14 SLOWDOWN="0.96"
  15
  16 destdir="$1"
  17 infile="$2"
  18 outfile="$destdir/$(basename "$infile")"
  19 tmpdir="$(tempfile -p 'pal-')"
  20 rm "$tmpdir"
  21
  22 if [ -f "$outfile" ]; then
  23         echo "Not overwriting $outfile"
  24         exit 0
  25 fi
  26
  27 set -x
  28 mkdir "$tmpdir"
  29 mplayer -novideo -ao pcm:file="${tmpdir}/audio.wav" -vo null "$infile"
  30 sox "${tmpdir}/audio.wav" "${tmpdir}/audio-fixed.wav" speed "${SLOWDOWN}" gain -n
  31 lame --preset standard "${tmpdir}/audio-fixed.wav" "${tmpdir}/audio.mp3"
  32 mkvmerge -o "${outfile}" --default-duration "1:${FORCEFPS}fps" --no-audio "$infile" "${tmpdir}/audio.mp3"
  33
  34 rm -rf "$tmpdir"
  35