Try to fix up subtitle timing a bit.

4 files changed, 7 insertions, 6 deletions

diff --git a/src/lib/decoder.cc b/src/lib/decoder.cc
index c0ad85da3..da75decc8 100644
--- a/src/lib/decoder.cc
+++ b/src/lib/decoder.cc
@@ -352,7 +352,7 @@ Decoder::process_video (AVFrame* frame)
 			}
 
 			shared_ptr<Subtitle> sub;
-			if (_timed_subtitle && _timed_subtitle->displayed_at (double (last_video_frame()) / rint (_fs->frames_per_second()))) {
+			if (_timed_subtitle && _timed_subtitle->displayed_at (double (last_video_frame()) / _fs->frames_per_second())) {
 				sub = _timed_subtitle->subtitle ();
 			}
 
diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index e2aa8add0..e954294ec 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -304,7 +304,7 @@ FFmpegDecoder::do_pass ()
 			process_audio (_frame->data[0], data_size);
 		}
 			
-	} else if (_subtitle_stream >= 0 && _packet.stream_index == _subtitle_stream && _opt->decode_subtitles) {
+	} else if (_subtitle_stream >= 0 && _packet.stream_index == _subtitle_stream && _opt->decode_subtitles && _first_video) {
 
 		int got_subtitle;
 		AVSubtitle sub;
@@ -313,7 +313,7 @@ FFmpegDecoder::do_pass ()
 			   no AVSubtitleRects.
 			*/
 			if (sub.num_rects > 0) {
-				process_subtitle (shared_ptr<TimedSubtitle> (new TimedSubtitle (sub)));
+				process_subtitle (shared_ptr<TimedSubtitle> (new TimedSubtitle (sub, _first_video.get())));
 			}
 			avsubtitle_free (&sub);
 		}
diff --git a/src/lib/subtitle.cc b/src/lib/subtitle.cc
index f851d5643..37c372c20 100644
--- a/src/lib/subtitle.cc
+++ b/src/lib/subtitle.cc
@@ -32,13 +32,14 @@ using namespace boost;
 /** Construct a TimedSubtitle.  This is a subtitle image, position,
  *  and a range of time over which it should be shown.
  *  @param sub AVSubtitle to read.
+ *  @param c Fractional seconds that should be subtracted from the AVSubtitle's PTS.
  */
-TimedSubtitle::TimedSubtitle (AVSubtitle const & sub)
+TimedSubtitle::TimedSubtitle (AVSubtitle const & sub, double c)
 {
 	assert (sub.rects > 0);
 	
 	/* subtitle PTS in seconds */
-	float const packet_time = (sub.pts / AV_TIME_BASE) + float (sub.pts % AV_TIME_BASE) / 1e6;
+	double const packet_time = ((sub.pts / AV_TIME_BASE) + float (sub.pts % AV_TIME_BASE) / 1e6) - c;
 	
 	/* hence start time for this sub */
 	_from = packet_time + (double (sub.start_display_time) / 1e3);
diff --git a/src/lib/subtitle.h b/src/lib/subtitle.h
index 38ba4e70e..590e0dd31 100644
--- a/src/lib/subtitle.h
+++ b/src/lib/subtitle.h
@@ -63,7 +63,7 @@ subtitle_transformed_area (
 class TimedSubtitle
 {
 public:
-	TimedSubtitle (AVSubtitle const &);
+	TimedSubtitle (AVSubtitle const &, double c);
 
 	bool displayed_at (double t) const;