X-Git-Url: https://code.delx.au/transcoding/blobdiff_plain/21ef2ffe6ac21ee9c34dbf029132dcf8bf3da9b7..3f4e270f745bb047a89416d6f2d9a6b2977611c2:/fix-pal-speedup

diff --git a/fix-pal-speedup b/fix-pal-speedup
index 85e7d1e..05a4b9a 100755
--- a/fix-pal-speedup
+++ b/fix-pal-speedup
@@ -2,16 +2,45 @@
 
 # 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
-# volume 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
 fi
 
+set -xe
 FORCEFPS="24"
-SLOWDOWN="0.96"
+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}"
+}
+
 
 destdir="$1"
 shift
@@ -24,14 +53,8 @@ for infile in "$@"; do
         continue
     fi
 
-    set -x
     tmpdir="$(mktemp -d "${TMPDIR:-/var/tmp}/pal-XXXXXXXX")"
-    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" "${tmpdir}/audio.mp3"
-    trackid="$(mkvmerge -i "$infile" | grep video | sed 's/^Track ID \(.\):.*$/\1/')"
-    mkvmerge -o "${outfile}" --default-duration "${trackid}:${FORCEFPS}fps" --no-audio "$infile" "${tmpdir}/audio.mp3"
-
+    convert_file "$infile" "$outfile"
     rm -rf "$tmpdir"
 done