# Many DVDs released in Australia are sped up from 24fps to 25fps.
# This script reverses the procedure, correcting the audio pitch.
-# The video framerate is adjusted without re-encoding. The audio is slowed and
-# normalised then re-encoded as mp3.
+# The video framerate is adjusted without re-encoding. The audio is
+# slowed, volume normalised, down-mixed to stereo and encoded as mp3.
if [ -z "$1" -o -z "$2" ]; then
- echo "Usage: $0 destdir infile"
- exit 1
+ echo "Usage: $0 destdir infile [infile ...]"
+ exit 1
fi
+set -xe
FORCEFPS="24"
SLOWDOWN="0.96"
+function mux_replace_audio {
+ local infile="$1"
+ local audiofile="$2"
+ local outfile="$3"
+
+ local trackid="$(mkvmerge -i "$infile" | grep 'Track ID.*video' | sed 's/^Track ID \(.\):.*$/\1/')"
+ mkvmerge -o "${outfile}" --default-duration "${trackid}:${FORCEFPS}fps" --no-audio "$infile" "$audiofile"
+}
+
+function extract_audio {
+ local infile="$1"
+ local outfile="$2"
+
+ mplayer \
+ -noconfig all \
+ -novideo \
+ -ao "pcm:waveheader:file=${outfile}" \
+ "$infile"
+}
+
+function slow_audio {
+ local infile="$1"
+ local outfile="$2"
+
+ sox \
+ --temp "$tmpdir" \
+ "$infile" \
+ -t wav \
+ "$outfile" \
+ speed "${SLOWDOWN}" \
+ gain -n
+}
+
+function encode_audio {
+ local infile="$1"
+ local outfile="$2"
+
+ lame \
+ --preset standard \
+ "${infile}" "${outfile}"
+}
+
+function convert_file {
+ local infile="$1"
+ local outfile="$2"
+ local audio1="${tmpdir}/audio1.wav"
+ local audio2="${tmpdir}/audio2.wav"
+ local audio3="${tmpdir}/audio3.mp3"
+
+ extract_audio "${infile}" "${audio1}"
+ slow_audio "${audio1}" "${audio2}"
+ encode_audio "${audio2}" "${audio3}"
+ mux_replace_audio "${infile}" "${audio3}" "${outfile}"
+}
+
+
destdir="$1"
-infile="$2"
-outfile="$destdir/$(basename "$infile")"
-tmpdir="$(tempfile -p 'pal-')"
-rm "$tmpdir"
-
-if [ -f "$outfile" ]; then
- echo "Not overwriting $outfile"
- exit 0
-fi
+shift
+
+for infile in "$@"; do
+ outfile="$destdir/$(basename "$infile")"
-set -x
-mkdir "$tmpdir"
-mplayer -novideo -ao pcm:file="${tmpdir}/audio.wav" -vo null "$infile"
-sox "${tmpdir}/audio.wav" "${tmpdir}/audio-fixed.wav" speed "${SLOWDOWN}" gain -n
-lame --preset standard "${tmpdir}/audio-fixed.wav" "${tmpdir}/audio.mp3"
-mkvmerge -o "${outfile}" --default-duration "1:${FORCEFPS}fps" --no-audio "$infile" "${tmpdir}/audio.mp3"
+ if [ -f "$outfile" ]; then
+ echo "Not overwriting $outfile"
+ continue
+ fi
-rm -rf "$tmpdir"
+ tmpdir="$(mktemp -d "${TMPDIR:-/var/tmp}/pal-XXXXXXXX")"
+ convert_file "$infile" "$outfile"
+ rm -rf "$tmpdir"
+done