Various work on the audio code.

1 files changed, 77 insertions, 0 deletions

diff --git a/src/lib/audio_merger.cc b/src/lib/audio_merger.cc
new file mode 100644
index 000000000..a0d300b7f
--- /dev/null
+++ b/src/lib/audio_merger.cc
@@ -0,0 +1,77 @@
+/*
+    Copyright (C) 2013-2016 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
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include "audio_merger.h"
+#include "dcpomatic_time.h"
+
+using std::pair;
+using std::min;
+using std::max;
+using std::make_pair;
+using boost::shared_ptr;
+
+AudioMerger::AudioMerger (int channels, int frame_rate)
+	: _buffers (new AudioBuffers (channels, 0))
+	, _last_pull (0)
+	, _frame_rate (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>
+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);
+	}
+	_buffers->set_frames (_buffers->frames() - to_return_from_buffers);
+
+	return make_pair (out, out_time);
+}
+
+void
+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);
+}