Partial fix to sync according to pts.

4 files changed, 34 insertions, 1 deletions

diff --git a/src/lib/decoder.h b/src/lib/decoder.h
index 2285cf4f9..7559217eb 100644
--- a/src/lib/decoder.h
+++ b/src/lib/decoder.h
@@ -71,6 +71,11 @@ public:
 	virtual int64_t audio_channel_layout () const = 0;
 	virtual bool has_subtitles () const = 0;
 
+	/** @return amount of extra unwanted audio at the start (or -ve for unwanted video) in milliseconds */
+	virtual int audio_to_discard () const {
+		return 0;
+	}
+
 	void process_begin ();
 	bool pass ();
 	void process_end ();
diff --git a/src/lib/examine_content_job.cc b/src/lib/examine_content_job.cc
index cad560908..d91fc2136 100644
--- a/src/lib/examine_content_job.cc
+++ b/src/lib/examine_content_job.cc
@@ -28,6 +28,7 @@
 #include "decoder.h"
 #include "imagemagick_encoder.h"
 #include "transcoder.h"
+#include "log.h"
 
 using namespace std;
 using namespace boost;
@@ -67,7 +68,12 @@ ExamineContentJob::run ()
 
 	_decoder = decoder_factory (fs, o, this, _log, true, true);
 	_decoder->go ();
-	fs->set_length (last_video_frame ());
+
+	fs->set_length (_decoder->last_video_frame ());
+	fs->set_audio_delay (-_decoder->audio_to_discard ());
+
+	_log->log (String::compose ("Video length is %1 frames", _decoder->last_video_frame()));
+	_log->log (String::compose ("%1ms of audio to discard", _decoder->audio_to_discard()));
 
 	ascend ();
 
diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index e52ea735f..d8a541be3 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -66,6 +66,7 @@ FFmpegDecoder::FFmpegDecoder (boost::shared_ptr<const FilmState> s, boost::share
 	, _audio_codec (0)
 	, _subtitle_codec_context (0)
 	, _subtitle_codec (0)
+	, _first_video_pts (-1)
 {
 	setup_general ();
 	setup_video ();
@@ -221,6 +222,8 @@ FFmpegDecoder::do_pass ()
 		_packet.data = 0;
 		_packet.size = 0;
 
+		/* XXX: should we reset _packet.data and size after each *_decode_* call? */
+
 		int frame_finished;
 
 		while (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
@@ -245,6 +248,9 @@ FFmpegDecoder::do_pass ()
 
 		int frame_finished;
 		if (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
+			if (_first_video_pts == -1) {
+				_first_video_pts = _packet.pts;
+			}
 			process_video (_frame);
 		}
 
@@ -417,3 +423,15 @@ FFmpegDecoder::stream_name (AVStream* s) const
 
 	return n.str ();
 }
+
+int
+FFmpegDecoder::audio_to_discard () const
+{
+	AVStream* v = _format_context->streams[_video_stream];
+	AVStream* a = _format_context->streams[_audio_stream];
+
+	assert (v->time_base.num == a->time_base.num);
+	assert (v->time_base.den == a->time_base.den);
+
+	return rint (av_q2d (v->time_base) * 1000 * (_first_video_pts - _first_audio_pts));
+}
diff --git a/src/lib/ffmpeg_decoder.h b/src/lib/ffmpeg_decoder.h
index 339afbaef..dc10635a5 100644
--- a/src/lib/ffmpeg_decoder.h
+++ b/src/lib/ffmpeg_decoder.h
@@ -66,6 +66,7 @@ public:
 	int64_t audio_channel_layout () const;
 	bool has_subtitles () const;
 	int bytes_per_audio_sample () const;
+	int audio_to_discard () const;
 
 	std::vector<AudioStream> audio_streams () const;
 	std::vector<SubtitleStream> subtitle_streams () const;
@@ -105,4 +106,7 @@ private:
 	AVCodec* _subtitle_codec;                ///< may be 0 if there is no subtitle
 
 	AVPacket _packet;
+
+	int64_t _first_video_pts;
+	int64_t _first_audio_pts;
 };