Fix merging of audio in various circumstances.

1 files changed, 88 insertions, 30 deletions

diff --git a/src/lib/audio_merger.cc b/src/lib/audio_merger.cc
index 49cdea6a3..5e0589bb1 100644
--- a/src/lib/audio_merger.cc
+++ b/src/lib/audio_merger.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2013-2016 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2013-2017 Carl Hetherington <cth@carlh.net>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -24,12 +24,14 @@
 using std::pair;
 using std::min;
 using std::max;
+using std::list;
+using std::cout;
 using std::make_pair;
 using boost::shared_ptr;
+using boost::optional;
 
-AudioMerger::AudioMerger (int channels, int frame_rate)
-	: _buffers (new AudioBuffers (channels, 0))
-	, _last_pull (0)
+AudioMerger::AudioMerger (int frame_rate)
+	: _last_pull (0)
 	, _frame_rate (frame_rate)
 {
 
@@ -38,31 +40,36 @@ AudioMerger::AudioMerger (int channels, int frame_rate)
 /** Pull audio up to a given time; after this call, no more data can be pushed
  *  before the specified time.
  */
-pair<shared_ptr<AudioBuffers>, DCPTime>
+list<pair<shared_ptr<AudioBuffers>, DCPTime> >
 AudioMerger::pull (DCPTime time)
 {
-	/* Number of frames to return */
-	Frame const to_return = time.frames_floor (_frame_rate) - _last_pull.frames_floor (_frame_rate);
-	shared_ptr<AudioBuffers> out (new AudioBuffers (_buffers->channels(), to_return));
-
-	/* And this is how many we will get from our buffer */
-	Frame const to_return_from_buffers = min (to_return, Frame (_buffers->frames()));
-
-	/* Copy the data that we have to the back end of the return buffer */
-	out->copy_from (_buffers.get(), to_return_from_buffers, 0, to_return - to_return_from_buffers);
-	/* Silence any gap at the start */
-	out->make_silent (0, to_return - to_return_from_buffers);
-
-	DCPTime out_time = _last_pull;
-	_last_pull = time;
-
-	/* And remove the data we're returning from our buffers */
-	if (_buffers->frames() > to_return_from_buffers) {
-		_buffers->move (to_return_from_buffers, 0, _buffers->frames() - to_return_from_buffers);
+	list<pair<shared_ptr<AudioBuffers>, DCPTime> > out;
+
+	DCPTimePeriod period (_last_pull, time);
+	_buffers.sort (AudioMerger::BufferComparator());
+
+	list<Buffer> new_buffers;
+
+	BOOST_FOREACH (Buffer i, _buffers) {
+		if (i.period().to < time) {
+			/* Completely within the pull period */
+			out.push_back (make_pair (i.audio, i.time));
+		} else if (i.time < time) {
+			/* Overlaps the end of the pull period */
+			shared_ptr<AudioBuffers> audio (new AudioBuffers (i.audio->channels(), DCPTime(time - i.time).frames_floor(_frame_rate)));
+			audio->copy_from (i.audio.get(), audio->frames(), 0, 0);
+			out.push_back (make_pair (audio, i.time));
+			i.audio->trim_start (audio->frames ());
+			i.time += DCPTime::from_frames(audio->frames(), _frame_rate);
+			new_buffers.push_back (i);
+		} else {
+			/* Not involved */
+			new_buffers.push_back (i);
+		}
 	}
-	_buffers->set_frames (_buffers->frames() - to_return_from_buffers);
 
-	return make_pair (out, out_time);
+	_buffers = new_buffers;
+	return out;
 }
 
 void
@@ -70,9 +77,60 @@ AudioMerger::push (boost::shared_ptr<const AudioBuffers> audio, DCPTime time)
 {
 	DCPOMATIC_ASSERT (time >= _last_pull);
 
-	Frame const frame = time.frames_floor (_frame_rate);
-	Frame after = max (Frame (_buffers->frames()), frame + audio->frames() - _last_pull.frames_floor (_frame_rate));
-	_buffers->ensure_size (after);
-	_buffers->accumulate_frames (audio.get(), 0, frame - _last_pull.frames_floor (_frame_rate), audio->frames ());
-	_buffers->set_frames (after);
+	DCPTimePeriod period (time, time + DCPTime::from_frames (audio->frames(), _frame_rate));
+
+	/* Mix any parts of this new block with existing ones */
+	BOOST_FOREACH (Buffer i, _buffers) {
+		optional<DCPTimePeriod> overlap = i.period().overlap (period);
+		if (overlap) {
+			int32_t const offset = DCPTime(overlap->from - i.time).frames_floor(_frame_rate);
+			int32_t const frames = overlap->duration().frames_floor(_frame_rate);
+			if (i.time < time) {
+				i.audio->accumulate_frames(audio.get(), frames, 0, offset);
+			} else {
+				i.audio->accumulate_frames(audio.get(), frames, offset, 0);
+			}
+		}
+	}
+
+	list<DCPTimePeriod> periods;
+	BOOST_FOREACH (Buffer i, _buffers) {
+		periods.push_back (i.period ());
+	}
+
+	/* Add the non-overlapping parts */
+	BOOST_FOREACH (DCPTimePeriod i, subtract (period, periods)) {
+		list<Buffer>::iterator before = _buffers.end();
+		list<Buffer>::iterator after = _buffers.end();
+		for (list<Buffer>::iterator j = _buffers.begin(); j != _buffers.end(); ++j) {
+			if (j->period().to == i.from) {
+				before = j;
+			}
+			if (j->period().from == i.to) {
+				after = j;
+			}
+		}
+
+		/* Get the part of audio that we want to use */
+		shared_ptr<AudioBuffers> part (new AudioBuffers (audio->channels(), i.to.frames_floor(_frame_rate) - i.from.frames_floor(_frame_rate)));
+		part->copy_from (audio.get(), part->frames(), DCPTime(i.from - time).frames_floor(_frame_rate), 0);
+
+		if (before == _buffers.end() && after == _buffers.end()) {
+			/* New buffer */
+			_buffers.push_back (Buffer (part, time, _frame_rate));
+		} else if (before != _buffers.end() && after == _buffers.end()) {
+			/* We have an existing buffer before this one; append new data to it */
+			before->audio->append (part);
+		} else if (before ==_buffers.end() && after != _buffers.end()) {
+			/* We have an existing buffer after this one; append it to the new data and replace */
+			part->append (after->audio);
+			after->audio = part;
+			after->time = time;
+		} else {
+			/* We have existing buffers both before and after; coalesce them all */
+			before->audio->append (part);
+			before->audio->append (after->audio);
+			_buffers.erase (after);
+		}
+	}
 }