Fix overlapping burnt-in subtitles in some cases (#959).

[dcpomatic.git] / src / lib / text_subtitle_decoder.cc

diff --git a/src/lib/text_subtitle_decoder.cc b/src/lib/text_subtitle_decoder.cc
index bec2ab9b7b32029802e2d8dbdb8a5efb62a378a7..05bde829cb6237dcb4a02d7d14ff4ab6372278bf 100644 (file)
--- a/src/lib/text_subtitle_decoder.cc
+++ b/src/lib/text_subtitle_decoder.cc
@@ -85,10 +85,20 @@ TextSubtitleDecoder::text_subtitles_during (ContentTimePeriod p, bool starting)
 
        list<ContentTimePeriod> d;
 
+       /* Only take `during' (not starting) subs if they overlap more than half the requested period;
+          here's the threshold for being significant.
+       */
+       ContentTime const significant (p.duration().get() / 2);
+
        for (vector<sub::Subtitle>::const_iterator i = _subtitles.begin(); i != _subtitles.end(); ++i) {
                ContentTimePeriod t = content_time_period (*i);
-               if ((starting && p.contains (t.from)) || (!starting && p.overlap (t))) {
+               if (starting && p.contains(t.from)) {
                        d.push_back (t);
+               } else if (!starting) {
+                       optional<ContentTimePeriod> const o = p.overlap (t);
+                       if (o && o->duration() > significant) {
+                               d.push_back (t);
+                       }
                }
        }