Timestamp audio emissions from butler and hence discard very late

audio in FilmViewer.  This should help with the case where lots
of video frames are rapidly discarded when they are late but the
corresponding audio is not, hence audio buffers get overfilled.

1 files changed, 26 insertions, 16 deletions

diff --git a/src/lib/audio_ring_buffers.cc b/src/lib/audio_ring_buffers.cc
index 42115efa3..f51ff8a38 100644
--- a/src/lib/audio_ring_buffers.cc
+++ b/src/lib/audio_ring_buffers.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2016-2017 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2016-2018 Carl Hetherington <cth@carlh.net>
 
     This file is part of DCP-o-matic.
 
@@ -26,7 +26,11 @@
 
 using std::min;
 using std::cout;
+using std::make_pair;
+using std::pair;
+using std::list;
 using boost::shared_ptr;
+using boost::optional;
 
 AudioRingBuffers::AudioRingBuffers ()
 	: _used_in_head (0)
@@ -35,23 +39,26 @@ AudioRingBuffers::AudioRingBuffers ()
 }
 
 void
-AudioRingBuffers::put (shared_ptr<const AudioBuffers> data)
+AudioRingBuffers::put (shared_ptr<const AudioBuffers> data, DCPTime time)
 {
 	boost::mutex::scoped_lock lm (_mutex);
 
-	if (!_buffers.empty ()) {
-		DCPOMATIC_ASSERT (_buffers.front()->channels() == data->channels());
+	if (!_buffers.empty()) {
+		DCPOMATIC_ASSERT (_buffers.front().first->channels() == data->channels());
+		DCPOMATIC_ASSERT ((_buffers.back().second + DCPTime::from_frames(_buffers.back().first->frames(), 48000)) == time);
 	}
 
-	_buffers.push_back (data);
+	_buffers.push_back(make_pair(data, time));
 }
 
-/** @return true if there was an underrun, otherwise false */
-bool
+/** @return time of the returned data; if it's not set this indicates an underrun */
+optional<DCPTime>
 AudioRingBuffers::get (float* out, int channels, int frames)
 {
 	boost::mutex::scoped_lock lm (_mutex);
 
+	optional<DCPTime> time;
+
 	while (frames > 0) {
 		if (_buffers.empty ()) {
 			for (int i = 0; i < frames; ++i) {
@@ -60,14 +67,17 @@ AudioRingBuffers::get (float* out, int channels, int frames)
 				}
 			}
 			cout << "audio underrun; missing " << frames << "!\n";
-			return true;
+			return time;
 		}
 
-		shared_ptr<const AudioBuffers> front = _buffers.front ();
+		pair<shared_ptr<const AudioBuffers>, DCPTime> front = _buffers.front ();
+		if (!time) {
+			time = front.second + DCPTime::from_frames(_used_in_head, 48000);
+		}
 
-		int const to_do = min (frames, front->frames() - _used_in_head);
-		float** p = front->data();
-		int const c = min (front->channels(), channels);
+		int const to_do = min (frames, front.first->frames() - _used_in_head);
+		float** p = front.first->data();
+		int const c = min (front.first->channels(), channels);
 		for (int i = 0; i < to_do; ++i) {
 			for (int j = 0; j < c; ++j) {
 				*out++ = p[j][i + _used_in_head];
@@ -79,13 +89,13 @@ AudioRingBuffers::get (float* out, int channels, int frames)
 		_used_in_head += to_do;
 		frames -= to_do;
 
-		if (_used_in_head == front->frames()) {
+		if (_used_in_head == front.first->frames()) {
 			_buffers.pop_front ();
 			_used_in_head = 0;
 		}
 	}
 
-	return false;
+	return time;
 }
 
 void
@@ -101,8 +111,8 @@ AudioRingBuffers::size () const
 {
 	boost::mutex::scoped_lock lm (_mutex);
 	Frame s = 0;
-	BOOST_FOREACH (shared_ptr<const AudioBuffers> i, _buffers) {
-		s += i->frames ();
+	for (list<pair<shared_ptr<const AudioBuffers>, DCPTime> >::const_iterator i = _buffers.begin(); i != _buffers.end(); ++i) {
+		s += i->first->frames();
 	}
 	return s - _used_in_head;
 }