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/*
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"
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))
, _next_emission (0)
, _t_to_f (t_to_f)
, _f_to_t (f_to_t)
{}
void push (boost::shared_ptr<const AudioBuffers> audio, T time)
{
if (time > _next_emission) {
/* We can emit some audio from our buffer; this is how many frames
we are going to emit.
*/
F const to_emit = _t_to_f (time - _next_emission);
boost::shared_ptr<AudioBuffers> emit (new AudioBuffers (_buffers->channels(), to_emit));
/* And this is how many we will get from our buffer */
F const to_emit_from_buffers = min (to_emit, _buffers->frames ());
/* Copy the data that we have to the back end of `emit' */
emit->copy_from (_buffers.get(), to_emit_from_buffers, 0, to_emit - to_emit_from_buffers);
/* Silence any gap at the start */
emit->make_silent (0, to_emit - to_emit_from_buffers);
/* Emit that */
Audio (emit, _next_emission);
_next_emission += _f_to_t (to_emit);
/* And remove the data we've emitted from our buffers */
if (_buffers->frames() > to_emit_from_buffers) {
_buffers->move (to_emit_from_buffers, 0, _buffers->frames() - to_emit_from_buffers);
}
_buffers->set_frames (_buffers->frames() - to_emit_from_buffers);
}
/* Now accumulate the new audio into our buffers */
F frame = _t_to_f (time);
F after = max (_buffers->frames(), frame + audio->frames() - _t_to_f (_next_emission));
_buffers->ensure_size (after);
_buffers->accumulate_frames (audio.get(), 0, frame - _t_to_f (_next_emission), 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;
}
void flush ()
{
if (_buffers->frames() > 0) {
Audio (_buffers, _next_emission);
}
}
boost::signals2::signal<void (boost::shared_ptr<const AudioBuffers>, T)> Audio;
private:
boost::shared_ptr<AudioBuffers> _buffers;
T _next_emission;
boost::function<F (T)> _t_to_f;
boost::function<T (F)> _f_to_t;
};
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