From 1ccf4d163d1897e76c5536d1c334f664d813a91f Mon Sep 17 00:00:00 2001
From: James Bunton <jamesbunton@delx.net.au>
Date: Thu, 29 Jun 2017 21:37:20 +1000
Subject: [PATCH] fix-pal-speedup: delay audio track when necessary

---
 fix-pal-speedup | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/fix-pal-speedup b/fix-pal-speedup
index b8cee2c..5eddef8 100755
--- a/fix-pal-speedup
+++ b/fix-pal-speedup
@@ -19,8 +19,24 @@ function mux_replace_audio {
     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"
+    local audiodelay="$(get_audio_delay "$infile")"
+    local videotrackid="$(get_video_trackid "$infile")"
+
+    mkvmerge \
+        -o "${outfile}" \
+        --default-duration "${videotrackid}:${FORCEFPS}fps" \
+        --no-audio "$infile" \
+        --sync "0:$((audiodelay / 1000000))" \
+        "$audiofile"
+}
+
+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 {
@@ -37,8 +53,8 @@ function convert_file {
     local outfile="$2"
     local audiofile="${tmpdir}/audiofile.m4a"
 
-    encode_audio "${infile}" "${audiofile}"
-    mux_replace_audio "${infile}" "${audiofile}" "${outfile}"
+    encode_audio "$infile" "$audiofile"
+    mux_replace_audio "$infile" "$audiofile" "$outfile"
 }
 
 
-- 
2.39.2