From 43d540854fe75e01292891a299f852407ff54d65 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Sun, 23 Apr 2017 21:23:21 +0100
Subject: [PATCH] Discard audio received before the time of the last accurate
 seek.

---
 src/lib/player.cc | 42 ++++++++++++++++++++++++++++++------------
 src/lib/player.h  |  1 +
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/src/lib/player.cc b/src/lib/player.cc
index 5fb349b0e..e59451abe 100644
--- a/src/lib/player.cc
+++ b/src/lib/player.cc
@@ -585,12 +585,20 @@ Player::pass ()
 	list<pair<shared_ptr<AudioBuffers>, DCPTime> > audio = _audio_merger.pull (pull_from);
 	for (list<pair<shared_ptr<AudioBuffers>, DCPTime> >::iterator i = audio.begin(); i != audio.end(); ++i) {
 		if (_last_audio_time && i->second < _last_audio_time.get()) {
-			cout << "FAIL " << to_string(i->second) << " " << to_string(_last_audio_time.get()) << "\n";
+			/* There has been an accurate seek and we have received some audio before the seek time;
+			   discard it.
+			*/
+			pair<shared_ptr<AudioBuffers>, DCPTime> cut = discard_audio (i->first, i->second, *_last_audio_time);
+			if (!cut.first) {
+				continue;
+			}
+			*i = cut;
 		}
-		DCPOMATIC_ASSERT (!_last_audio_time || i->second >= _last_audio_time.get());
+
 		if (_last_audio_time) {
 			fill_audio (DCPTimePeriod (_last_audio_time.get(), i->second));
 		}
+
 		Audio (i->first, i->second);
 		_last_audio_time = i->second + DCPTime::from_frames(i->first->frames(), _film->audio_frame_rate());
 	}
@@ -795,17 +803,13 @@ Player::audio (weak_ptr<Piece> wp, AudioStreamPtr stream, ContentAudio content_a
 
 	/* Remove anything that comes before the start or after the end of the content */
 	if (time < piece->content->position()) {
-		DCPTime const discard_time = piece->content->position() - time;
-		Frame discard_frames = discard_time.frames_round(_film->audio_frame_rate());
-		Frame remaining_frames = content_audio.audio->frames() - discard_frames;
-		if (remaining_frames <= 0) {
+		pair<shared_ptr<AudioBuffers>, DCPTime> cut = discard_audio (content_audio.audio, time, piece->content->position());
+		if (!cut.first) {
 			/* This audio is entirely discarded */
 			return;
 		}
-		shared_ptr<AudioBuffers> cut (new AudioBuffers (content_audio.audio->channels(), remaining_frames));
-		cut->copy_from (content_audio.audio.get(), remaining_frames, discard_frames, 0);
-		content_audio.audio = cut;
-		time += discard_time;
+		content_audio.audio = cut.first;
+		time = cut.second;
 	} else if (time > piece->content->end()) {
 		/* Discard it all */
 		return;
@@ -907,6 +911,8 @@ Player::seek (DCPTime time, bool accurate)
 		i->second->reset ();
 	}
 
+	_audio_merger.clear ();
+
 	BOOST_FOREACH (shared_ptr<Piece> i, _pieces) {
 		i->done = false;
 		if (i->content->position() <= time && time < i->content->end()) {
@@ -917,11 +923,9 @@ Player::seek (DCPTime time, bool accurate)
 	if (accurate) {
 		_last_video_time = time - one_video_frame ();
 		_last_audio_time = time;
-		cout << "_last_audio_time -> " << to_string(time) << "\n";
 	} else {
 		_last_video_time = optional<DCPTime> ();
 		_last_audio_time = optional<DCPTime> ();
-		cout << "_last_audio_time -> []\n";
 	}
 }
 
@@ -990,3 +994,17 @@ Player::one_video_frame () const
 {
 	return DCPTime::from_frames (1, _film->video_frame_rate ());
 }
+
+pair<shared_ptr<AudioBuffers>, DCPTime>
+Player::discard_audio (shared_ptr<const AudioBuffers> audio, DCPTime time, DCPTime discard_to) const
+{
+	DCPTime const discard_time = discard_to - time;
+	Frame const discard_frames = discard_time.frames_round(_film->audio_frame_rate());
+	Frame remaining_frames = audio->frames() - discard_frames;
+	if (remaining_frames <= 0) {
+		return make_pair(shared_ptr<AudioBuffers>(), DCPTime());
+	}
+	shared_ptr<AudioBuffers> cut (new AudioBuffers (audio->channels(), remaining_frames));
+	cut->copy_from (audio.get(), remaining_frames, discard_frames, 0);
+	return make_pair(cut, time + discard_time);
+}
diff --git a/src/lib/player.h b/src/lib/player.h
index ea07e1fc8..dec4529ba 100644
--- a/src/lib/player.h
+++ b/src/lib/player.h
@@ -112,6 +112,7 @@ private:
 	void fill_audio (DCPTimePeriod period);
 	void audio_flush (boost::shared_ptr<Piece>, AudioStreamPtr stream);
 	void audio_transform (boost::shared_ptr<AudioContent> content, AudioStreamPtr stream, ContentAudio content_audio, DCPTime time);
+	std::pair<boost::shared_ptr<AudioBuffers>, DCPTime> discard_audio (boost::shared_ptr<const AudioBuffers> audio, DCPTime time, DCPTime discard_to) const;
 
 	boost::shared_ptr<const Film> _film;
 	boost::shared_ptr<const Playlist> _playlist;
-- 
2.30.2