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/*
Clip.cc
Copyright 2003-5 Tim Goetze <tim@quitte.de>
http://quitte.de/dsp/
simple oversampled hard clipper
*/
/*
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., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA or point your web browser to http://www.gnu.org.
*/
#include "basics.h"
#include "Clip.h"
#include "Descriptor.h"
void
Clip::init (double _fs)
{
fs = _fs;
gain = 1;
threshold[0] = -.9;
threshold[1] = +.9;
/* going a bit lower than nominal with fc */
double f = .5 * M_PI / OVERSAMPLE;
/* construct the upsampler filter kernel */
DSP::sinc (f, up.c, FIR_SIZE);
DSP::kaiser<DSP::apply_window> (up.c, FIR_SIZE, 6.4);
/* copy upsampler filter kernel for downsampler, make sum */
double s = 0;
for (int i = 0; i < up.n; ++i)
down.c[i] = up.c[i],
s += up.c[i];
/* scale downsampler kernel for unity gain */
s = 1 / s;
for (int i = 0; i < down.n; ++i)
down.c[i] *= s;
/* scale upsampler kernel for unity gain */
s *= OVERSAMPLE;
for (int i = 0; i < up.n; ++i)
up.c[i] *= s;
}
inline d_sample
Clip::clip (d_sample a)
{
if (a < threshold[0])
return threshold[0];
if (a > threshold[1])
return threshold[1];
return a;
}
template <sample_func_t F>
void
Clip::one_cycle (int frames)
{
d_sample * s = ports[0];
double gf;
if (*ports[1] == gain_db)
gf = 1;
else
{
gain_db = *ports[1];
d_sample g = DSP::db2lin (gain_db);
gf = pow (g / gain, 1 / (double) frames);
}
d_sample * d = ports[2];
*ports[3] = OVERSAMPLE;
for (int i = 0; i < frames; ++i)
{
register d_sample a = gain * s[i];
a = down.process (clip (up.upsample (a)));
for (int o = 1; o < OVERSAMPLE; ++o)
down.store (clip (up.pad (o)));
F (d, i, a, adding_gain);
gain *= gf;
}
}
/* //////////////////////////////////////////////////////////////////////// */
PortInfo
Clip::port_info [] =
{
{
"in",
INPUT | AUDIO,
{BOUNDED, -1, 1}
}, {
"gain (dB)",
INPUT | CONTROL,
{BOUNDED | DEFAULT_1, -72, 72}
}, {
"out",
OUTPUT | AUDIO,
{0}
}, {
"latency",
OUTPUT | CONTROL,
{0}
}
};
template <> void
Descriptor<Clip>::setup()
{
UniqueID = 1771;
Label = "Clip";
Properties = HARD_RT;
Name = "CAPS: Clip - Hard clipper, 8x oversampled";
Maker = "Tim Goetze <tim@quitte.de>";
Copyright = "GPL, 2003-5";
/* fill port info and vtable */
autogen();
}
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