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/*
Copyright (C) 2006 Paul Davis
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 <cstring>
#include <cmath>
#include <algorithm>
#include "ardour/amp.h"
#include "ardour/buffer_set.h"
#include "ardour/audio_buffer.h"
namespace ARDOUR {
/** Apply a declicked gain to the audio buffers of @a bufs */
void
Amp::run_in_place (BufferSet& bufs, nframes_t nframes, gain_t initial, gain_t target, bool invert_polarity)
{
if (nframes == 0)
return;
if (bufs.count().n_audio() == 0)
return;
// assert(bufs.buffer_capacity(DataType::AUDIO) >= nframes);
// if we don't need to declick, defer to apply_simple_gain
if (initial == target) {
if (target == 0.0) {
for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
memset (i->data(), 0, sizeof (Sample) * nframes);
}
} else if (target != 1.0) {
for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
apply_gain_to_buffer (i->data(), nframes, target);
}
}
return;
}
const nframes_t declick = std::min ((nframes_t)128, nframes);
gain_t delta;
double fractional_shift = -1.0/declick;
double fractional_pos;
gain_t polscale = invert_polarity ? -1.0f : 1.0f;
if (target < initial) {
/* fade out: remove more and more of delta from initial */
delta = -(initial - target);
} else {
/* fade in: add more and more of delta from initial */
delta = target - initial;
}
for (BufferSet::audio_iterator i = bufs.audio_begin(); i != bufs.audio_end(); ++i) {
Sample* const buffer = i->data();
fractional_pos = 1.0;
for (nframes_t nx = 0; nx < declick; ++nx) {
buffer[nx] *= polscale * (initial + (delta * (0.5 + 0.5 * cos (M_PI * fractional_pos))));
fractional_pos += fractional_shift;
}
/* now ensure the rest of the buffer has the target value applied, if necessary. */
if (declick != nframes) {
if (invert_polarity) {
target = -target;
}
if (target == 0.0) {
memset (&buffer[declick], 0, sizeof (Sample) * (nframes - declick));
} else if (target != 1.0) {
apply_gain_to_buffer (&buffer[declick], nframes - declick, target);
}
}
}
}
void
Amp::apply_simple_gain (BufferSet& bufs, nframes_t nframes, gain_t target)
{
}
} // namespace ARDOUR
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