X-Git-Url: https://code.delx.au/transcoding/blobdiff_plain/ef14618c34c9e025a97b374db7324763f77f0817..8a7446729d846bb3d5680add37ab2bab24b35963:/fix-pal-speedup

diff --git a/fix-pal-speedup b/fix-pal-speedup
index 3ac096e..b8cee2c 100755
--- a/fix-pal-speedup
+++ b/fix-pal-speedup
@@ -2,37 +2,48 @@
 
 # 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 [infile ...]"
-	exit 1
+    echo "Usage: $0 infile outfile"
+    exit 1
 fi
 
+set -xe
 FORCEFPS="24"
-SLOWDOWN="0.96"
-
-destdir="$1"
-shift
-
-for infile in "$@"; do
-	outfile="$destdir/$(basename "$infile")"
-	tmpdir="$(tempfile -p 'pal-')"
-	rm "$tmpdir"
-
-	if [ -f "$outfile" ]; then
-		echo "Not overwriting $outfile"
-		continue
-	fi
-
-	set -x
-	mkdir "$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" "${tmpdir}/audio.mp3"
-
-	rm -rf "$tmpdir"
-done
-
+SLOWFILTER="-filter asetrate=46080,aresample=osr=48000:resampler=soxr"
+
+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 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"