From 6bec4750da08011e944ab53bda1ff9a51065c795 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Mon, 22 Oct 2012 13:40:55 +0100
Subject: [PATCH] Try to make audio discard work properly.

---
 src/lib/decoder.cc    |  4 +++-
 src/lib/film.cc       |  1 +
 src/lib/film_state.cc | 12 ++++++++++++
 src/lib/film_state.h  | 13 +++++++++++++
 4 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/lib/decoder.cc b/src/lib/decoder.cc
index a90c14b2b..c9235f8e1 100644
--- a/src/lib/decoder.cc
+++ b/src/lib/decoder.cc
@@ -90,10 +90,12 @@ Decoder::~Decoder ()
 void
 Decoder::process_begin ()
 {
-	_delay_in_bytes = _fs->audio_delay() * _fs->audio_sample_rate() * _fs->audio_channels() * bytes_per_audio_sample() / 1000;
+	_delay_in_bytes = _fs->total_audio_delay() * _fs->audio_sample_rate() * _fs->audio_channels() * bytes_per_audio_sample() / 1000;
 	delete _delay_line;
 	_delay_line = new DelayLine (_delay_in_bytes);
 
+	_log->log (String::compose ("Decoding audio with total delay of %1", _fs->total_audio_delay()));
+
 	_audio_frames_processed = 0;
 }
 
diff --git a/src/lib/film.cc b/src/lib/film.cc
index aa0bfa211..3a8b29f86 100644
--- a/src/lib/film.cc
+++ b/src/lib/film.cc
@@ -256,6 +256,7 @@ void
 Film::examine_content_post_gui ()
 {
 	set_length (_examine_content_job->last_video_frame ());
+	set_audio_to_discard (_examine_content_job->audio_to_discard ());
 	_examine_content_job.reset ();
 
 	string const tdir = dir ("thumbs");
diff --git a/src/lib/film_state.cc b/src/lib/film_state.cc
index c8d519d71..deaacca84 100644
--- a/src/lib/film_state.cc
+++ b/src/lib/film_state.cc
@@ -809,6 +809,13 @@ FilmState::set_frames_per_second (float f)
 	_frames_per_second = f;
 	signal_changed (FRAMES_PER_SECOND);
 }
+
+void
+FilmState::set_audio_to_discard (int a)
+{
+	_audio_to_discard = a;
+	signal_changed (AUDIO_TO_DISCARD);
+}
 	
 void
 FilmState::signal_changed (Property p)
@@ -833,3 +840,8 @@ FilmState::audio_channels () const
 	return _audio_streams[_audio_stream].channels ();
 }
 
+int
+FilmState::total_audio_delay () const
+{
+	return _audio_delay - _audio_to_discard;
+}
diff --git a/src/lib/film_state.h b/src/lib/film_state.h
index 294b9aa10..d1d7489f6 100644
--- a/src/lib/film_state.h
+++ b/src/lib/film_state.h
@@ -73,6 +73,7 @@ public:
 		, _audio_sample_rate (0)
 		, _has_subtitles (false)
 		, _frames_per_second (0)
+		, _audio_to_discard (0)
 		, _dirty (false)
 	{}
 
@@ -113,6 +114,7 @@ public:
 		, _audio_streams     (o._audio_streams)
 		, _subtitle_streams  (o._subtitle_streams)
 		, _frames_per_second (o._frames_per_second)
+		, _audio_to_discard  (o._audio_to_discard)
 		, _dirty             (o._dirty)
 	{}
 
@@ -148,6 +150,7 @@ public:
 	}
 
 	int audio_channels () const;
+	int total_audio_delay () const;
 
 	enum Property {
 		NONE,
@@ -179,6 +182,7 @@ public:
 		AUDIO_STREAMS,
 		SUBTITLE_STREAMS,
 		FRAMES_PER_SECOND,
+		AUDIO_TO_DISCARD
 	};
 
 
@@ -338,6 +342,10 @@ public:
 		return _frames_per_second;
 	}
 
+	int audio_to_discard () const {
+		return _audio_to_discard;
+	}
+
 	
 	/* SET */
 
@@ -382,6 +390,7 @@ public:
 	void set_audio_streams (std::vector<AudioStream>);
 	void set_subtitle_streams (std::vector<SubtitleStream>);
 	void set_frames_per_second (float);
+	void set_audio_to_discard (int);
 
 	/** Emitted when some property has changed */
 	mutable sigc::signal1<void, Property> Changed;
@@ -471,6 +480,10 @@ private:
 	std::vector<SubtitleStream> _subtitle_streams;
 	/** Frames per second of the source */
 	float _frames_per_second;
+	/** Number of milliseconds of audio to discard at the start of this film
+	    in order to sync audio with video.  Can be negative.
+	*/
+	int _audio_to_discard;
 
 	mutable bool _dirty;
 
-- 
2.30.2