fix-pal-speedup now preserves surround sound for movies

[transcoding] / fix-pal-speedup

diff --git a/fix-pal-speedup b/fix-pal-speedup
index c6461374d71db1711ea421637751c25d535e2467..ab4949028287a9e1d9fb118ef64b83e4719cdd45 100755 (executable)
--- a/fix-pal-speedup
+++ b/fix-pal-speedup
@@ -3,7 +3,7 @@
 # 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, volume normalised, down-mixed to stereo and encoded as mp3.
+# slowed, and encoded as AAC, preserving surround sound.
 
 if [ -z "$1" -o -z "$2" ]; then
     echo "Usage: $0 destdir infile [infile ...]"
@@ -12,55 +12,47 @@ fi
 
 set -xe
 FORCEFPS="24"
-SLOWDOWN="0.96"
+SLOWFILTER="-filter asetrate=46080,aresample=48000"
 
 function mux_replace_audio {
-    infile="$1"
-    audiofile="$2"
-    outfile="$3"
+    local infile="$1"
+    local audiofile="$2"
+    local outfile="$3"
 
-    trackid="$(mkvmerge -i "$infile" | grep video | sed 's/^Track ID \(.\):.*$/\1/')"
-    exec mkvmerge -o "${outfile}" --default-duration "${trackid}:${FORCEFPS}fps" --no-audio "$infile" "$audiofile"
+    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 {
-    infile="$1"
-
-    exec mpv \
-        --no-terminal \
-        --no-video \
-        --ao pcm:waveheader:file=/dev/stdout \
+    local infile="$1"
+    local outfile="$2"
+
+    mplayer \
+        -noconfig all \
+        -novideo \
+        -channels 8 \
+        -dumpaudio \
+        -dumpfile "$outfile" \
         "$infile"
 }
 
-function slow_audio {
-    exec sox \
-        --temp "$tmpdir" \
-        - \
-        -t wav - \
-        speed "${SLOWDOWN}" \
-        gain -n \
-        channels 2
-}
-
 function encode_audio {
-    outfile="$1"
-    exec lame \
-        --preset standard \
-        - \
-        "${outfile}"
+    ffmpeg \
+        -i "$1" \
+        $SLOWFILTER \
+        -strict experimental \
+        "$2"
 }
 
 function convert_file {
-    infile="$1"
-    outfile="$2"
-    tmpdir="$(mktemp -d "${TMPDIR:-/var/tmp}/pal-XXXXXXXX")"
-    audiofile="${tmpdir}/audio.mp3"
-
-    extract_audio "${infile}" | slow_audio | encode_audio "${audiofile}"
-    mux_replace_audio "${infile}" "${audiofile}" "${outfile}"
-
-    rm -rf "$tmpdir"
+    local infile="$1"
+    local outfile="$2"
+    local audio1="${tmpdir}/audio1.ac3"
+    local audio2="${tmpdir}/audio2.m4a"
+
+    extract_audio "${infile}" "${audio1}"
+    encode_audio "${audio1}" "${audio2}"
+    mux_replace_audio "${infile}" "${audio2}" "${outfile}"
 }
 
 
@@ -75,6 +67,8 @@ for infile in "$@"; do
         continue
     fi
 
+    tmpdir="$(mktemp -d "${TMPDIR:-/var/tmp}/pal-XXXXXXXX")"
     convert_file "$infile" "$outfile"
+    rm -rf "$tmpdir"
 done