X-Git-Url: https://code.delx.au/transcoding/blobdiff_plain/cdba15d01c5c9cf934360e5e6e8aaa4432af40fa..b0c2d4418346c184c767022c5d7eb3573c83f621:/fix-pal-speedup

diff --git a/fix-pal-speedup b/fix-pal-speedup
index c951ed2..5eddef8 100755
--- a/fix-pal-speedup
+++ b/fix-pal-speedup
@@ -2,34 +2,64 @@
 
 # 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, and encoded as AAC, preserving surround sound.
 
 if [ -z "$1" -o -z "$2" ]; then
-	echo "Usage: $0 destdir infile"
-	exit 1
+    echo "Usage: $0 infile outfile"
+    exit 1
 fi
 
+set -xe
 FORCEFPS="24"
-SLOWDOWN="0.96"
+SLOWFILTER="-filter asetrate=46080,aresample=osr=48000:resampler=soxr"
 
-destdir="$1"
-infile="$2"
-outfile="$destdir/$(basename "$infile")"
-tmpdir="$(tempfile -p 'pal-')"
-rm "$tmpdir"
+function mux_replace_audio {
+    local infile="$1"
+    local audiofile="$2"
+    local outfile="$3"
 
-if [ -f "$outfile" ]; then
-	echo "Not overwriting $outfile"
-	exit 0
-fi
+    local audiodelay="$(get_audio_delay "$infile")"
+    local videotrackid="$(get_video_trackid "$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"
+    mkvmerge \
+        -o "${outfile}" \
+        --default-duration "${videotrackid}:${FORCEFPS}fps" \
+        --no-audio "$infile" \
+        --sync "0:$((audiodelay / 1000000))" \
+        "$audiofile"
+}
 
-rm -rf "$tmpdir"
+function get_video_trackid {
+    mkvmerge -i "$1" | sed -n 's/Track ID \([0-9]*\): .*video.*/\1/p'
+}
+
+function get_audio_delay {
+    mkvmerge -F verbose-text -i "$1" | \
+        sed -n 's/Track ID [0-9]*: .*audio.*minimum_timestamp:\([0-9]*\).*/\1/p'
+}
+
+function encode_audio {
+    ffmpeg \
+        -i "$1" \
+        -vn \
+        $SLOWFILTER \
+        -c:a libfdk_aac -vbr 3 \
+        "$2"
+}
 
+function convert_file {
+    local infile="$1"
+    local outfile="$2"
+    local audiofile="${tmpdir}/audiofile.m4a"
+
+    encode_audio "$infile" "$audiofile"
+    mux_replace_audio "$infile" "$audiofile" "$outfile"
+}
+
+
+infile="$1"
+outfile="$2"
+tmpdir="$(mktemp -d "${TMPDIR:-/var/tmp}/pal-XXXXXXXX")"
+convert_file "$infile" "$outfile"
+rm -rf "$tmpdir"