Use '-' instead of /dev/{stdin,stdout}

[transcoding] / fix-pal-speedup

diff --git a/fix-pal-speedup b/fix-pal-speedup
index 85e7d1e35c7f7ed408d2c45da81621d01d4d23f4..c6461374d71db1711ea421637751c25d535e2467 100755 (executable)
--- a/fix-pal-speedup
+++ b/fix-pal-speedup
@@ -2,17 +2,68 @@
 
 # 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, volume normalised, down-mixed to stereo and encoded as mp3.
 
 if [ -z "$1" -o -z "$2" ]; then
     echo "Usage: $0 destdir infile [infile ...]"
     exit 1
 fi
 
+set -xe
 FORCEFPS="24"
 SLOWDOWN="0.96"
 
+function mux_replace_audio {
+    infile="$1"
+    audiofile="$2"
+    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"
+}
+
+function extract_audio {
+    infile="$1"
+
+    exec mpv \
+        --no-terminal \
+        --no-video \
+        --ao pcm:waveheader:file=/dev/stdout \
+        "$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}"
+}
+
+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"
+}
+
+
 destdir="$1"
 shift
 
@@ -24,14 +75,6 @@ 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"
-
-    rm -rf "$tmpdir"
+    convert_file "$infile" "$outfile"
 done