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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"
#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;
};
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