1 files changed, 109 insertions, 0 deletions
diff --git a/src/lib/audio_merger.h b/src/lib/audio_merger.h
new file mode 100644
index 000000000..226601e0e
--- /dev/null
+++ b/src/lib/audio_merger.h
@@ -0,0 +1,109 @@
+/*
+    Copyright (C) 2013 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_buffers.h"
+#include "util.h"
+
+template <class T, class F>
+class AudioMerger
+{
+public:
+	AudioMerger (int channels, boost::function<F (T)> t_to_f, boost::function<T (F)> f_to_t)
+		: _buffers (new AudioBuffers (channels, 0))
+		, _last_pull (0)
+		, _t_to_f (t_to_f)
+		, _f_to_t (f_to_t)
+	{}
+
+	/** Pull audio up to a given time; after this call, no more data can be pushed
+	 *  before the specified time.
+	 */
+	TimedAudioBuffers<T>
+	pull (T time)
+	{
+		TimedAudioBuffers<T> out;
+		
+		F const to_return = _t_to_f (time - _last_pull);
+		out.audio.reset (new AudioBuffers (_buffers->channels(), to_return));
+		/* And this is how many we will get from our buffer */
+		F const to_return_from_buffers = min (to_return, _buffers->frames ());
+		
+		/* Copy the data that we have to the back end of the return buffer */
+		out.audio->copy_from (_buffers.get(), to_return_from_buffers, 0, to_return - to_return_from_buffers);
+		/* Silence any gap at the start */
+		out.audio->make_silent (0, to_return - to_return_from_buffers);
+		
+		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 out;
+	}
+
+	void
+	push (boost::shared_ptr<const AudioBuffers> audio, T time)
+	{
+		assert (time >= _last_pull);
+
+		F frame = _t_to_f (time);
+		F after = max (_buffers->frames(), frame + audio->frames() - _t_to_f (_last_pull));
+		_buffers->ensure_size (after);
+		_buffers->accumulate_frames (audio.get(), 0, frame - _t_to_f (_last_pull), audio->frames ());
+		_buffers->set_frames (after);
+	}
+
+	F min (F a, int b)
+	{
+		if (a < b) {
+			return a;
+		}
+
+		return b;
+	}
+
+	F max (int a, F b)
+	{
+		if (a > b) {
+			return a;
+		}
+
+		return b;
+	}
+		
+	TimedAudioBuffers<T>
+	flush ()
+	{
+		if (_buffers->frames() == 0) {
+			return TimedAudioBuffers<T> ();
+		}
+		
+		return TimedAudioBuffers<T> (_buffers, _last_pull);
+	}
+	
+private:
+	boost::shared_ptr<AudioBuffers> _buffers;
+	T _last_pull;
+	boost::function<F (T)> _t_to_f;
+	boost::function<T (F)> _f_to_t;
+};