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tdemultimedia/arts/modules/synth/synth_fm_source_impl.cc

62 lines
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/*
Copyright (C) 2000 Jeff Tranter
tranter@pobox.com
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include "artsmodulessynth.h"
#include "stdsynthmodule.h"
using namespace Arts;
// This is used for frequency modulation. Put your frequency to the
// frequency input and put another signal on the modulator input. Then
// set modlevel to something, say 0.3. The frequency will be modulated
// with modulator then. Just try it. Works nice when you put a
// feedback in there, that means take a combination of the delayed
// output signal from the Synth_FM_SOURCE (you need to put it to some
// oscillator as it only takes the role of Synth_FREQUENCY) and some
// other signal to get good results. Works nicely in combination with
// Synth_WAVE_SIN oscillators.
class Synth_FM_SOURCE_impl : virtual public Synth_FM_SOURCE_skel,
virtual public StdSynthModule
{
protected:
static const int SAMPLINGRATE = 44100;
float posn;
public:
void streamInit() { posn = 0; }
void calculateBlock(unsigned long samples)
{
for (unsigned long i=0; i<samples; i++)
{
float pinc = frequency[i] / (float) SAMPLINGRATE;
posn += pinc;
if (posn > 1)
posn -= 1;
pos[i] = posn + modulator[i] * modlevel[i];
}
}
};
REGISTER_IMPLEMENTATION(Synth_FM_SOURCE_impl);