fix-pal-speedup: don't try to adjust chapter-sync if there are zero chapters

[transcoding] / fix-pal-speedup

diff --git a/fix-pal-speedup b/fix-pal-speedup
index 5b77d451163c122b638e618f181167fd0f675064..51ab6ed52fcacf4742c489eec58bc2cc458aaaf5 100755 (executable)
--- a/fix-pal-speedup
+++ b/fix-pal-speedup
@@ -2,31 +2,74 @@
 
 # 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 encoded as AAC, preserving surround sound.
+# - The video framerate is adjusted without re-encoding.
+# - The audio is slowed, and encoded as AAC, preserving surround sound.
+# - Chapters and subtitles are also adjusted to match the new timing.
 
-if [ -z "$1" -o -z "$2" ]; then
+if [ -z "$1" ] || [ -z "$2" ]; then
     echo "Usage: $0 infile outfile"
     exit 1
 fi
 
 set -o pipefail -eux
-FORCEFPS="24"
-SLOWFILTER="-filter asetrate=46080,aresample=osr=48000:resampler=soxr"
+OLDFPS="25"
+NEWFPS="24"
+SLOWFILTER=("-filter" "asetrate=46080,aresample=osr=48000:resampler=soxr")
 
-function mux_replace_audio {
+function main {
+    local infile="$1"
+    local outfile="$2"
+
+    local tmpdir=""
+    tmpdir="$(mktemp -d "${TMPDIR:-/var/tmp}/pal-XXXXXXXX")"
+    local audiofile="${tmpdir}/audiofile.m4a"
+
+    encode_audio "$infile" "$audiofile"
+    remux_file "$infile" "$audiofile" "$outfile"
+
+    rm -rf "$tmpdir"
+}
+
+function encode_audio {
+    ffmpeg \
+        -i "$1" \
+        -vn \
+        "${SLOWFILTER[@]}" \
+        -c:a libfdk_aac -vbr 3 \
+        "$2"
+}
+
+function remux_file {
     local infile="$1"
     local audiofile="$2"
     local outfile="$3"
 
-    local audiodelay="$(get_minimum_timestamp "$infile" "audio")"
-    local videodelay="$(get_minimum_timestamp "$infile" "video")"
-    local videotrackid="$(get_track_id "$infile" "video")"
+    local audiodelay=""
+    audiodelay="$(get_minimum_timestamp "$infile" "audio")"
+
+    local videodelay=""
+    videodelay="$(get_minimum_timestamp "$infile" "video")"
+
+    local videotrackid=""
+    videotrackid="$(get_track_id "$infile" "video")"
+
+    local suboptions=()
+    local subtitletrackid=""
+    while read -r subtitletrackid; do
+        suboptions+=("--sync" "${subtitletrackid}:0,${OLDFPS}/${NEWFPS}")
+    done < <(get_track_id "$infile" "subtitles")
+
+    local chapteroptions=()
+    if [ "$(get_chapter_count "$infile")" -gt 0 ]; then
+        chapteroptions=("--chapter-sync" "0,${OLDFPS}/${NEWFPS}")
+    fi
 
     mkvmerge \
         -o "${outfile}" \
-        --default-duration "${videotrackid}:${FORCEFPS}fps" \
+        --default-duration "${videotrackid}:${NEWFPS}fps" \
         --sync "${videotrackid}:$((videodelay / 1000000))" \
+        "${chapteroptions[@]}" \
+        "${suboptions[@]}" \
         --no-audio "$infile" \
         --sync "0:$((audiodelay / 1000000))" \
         "$audiofile"
@@ -37,30 +80,11 @@ function get_track_id {
 }
 
 function get_minimum_timestamp {
-    mkvmerge -F json -i "$1" | jq -r ".tracks[] | select(.type == \"$2\") | .properties.minimum_timestamp"
+    mkvmerge -i -F json "$1" | jq -r ".tracks[] | select(.type == \"$2\") | .properties.minimum_timestamp"
 }
 
-function encode_audio {
-    ffmpeg \
-        -i "$1" \
-        -vn \
-        $SLOWFILTER \
-        -c:a libfdk_aac -vbr 3 \
-        "$2"
+function get_chapter_count {
+    mkvmerge -i -F json "$1" | jq -r ".chapters | length"
 }
 
-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"
+main "$@"