102 lines
2.4 KiB
C++
102 lines
2.4 KiB
C++
/*
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* Copyright (C) 2008-2011 Fons Adriaensen <fons@linuxaudio.org>
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* Copyright (C) 2013-2019 Robin Gareus <robin@gareus.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <math.h>
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#include "ardour/kmeterdsp.h"
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float Kmeterdsp::_omega;
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Kmeterdsp::Kmeterdsp (void)
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: _z1 (0)
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, _z2 (0)
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, _rms (0)
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, _flag (false)
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{}
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Kmeterdsp::~Kmeterdsp (void) {}
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void
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Kmeterdsp::init (int fsamp)
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{
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_omega = 9.72f / fsamp; // ballistic filter coefficient
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}
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void
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Kmeterdsp::process (float const* p, int n)
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{
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float s, z1, z2;
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// Get filter state.
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z1 = _z1 > 50 ? 50 : (_z1 < 0 ? 0 : _z1);
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z2 = _z2 > 50 ? 50 : (_z2 < 0 ? 0 : _z2);
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// Perform filtering. The second filter is evaluated
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// only every 4th sample - this is just an optimisation.
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n /= 4; // Loop is unrolled by 4.
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while (n--) {
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s = *p++;
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s *= s;
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z1 += _omega * (s - z1); // Update first filter.
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s = *p++;
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s *= s;
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z1 += _omega * (s - z1); // Update first filter.
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s = *p++;
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s *= s;
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z1 += _omega * (s - z1); // Update first filter.
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s = *p++;
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s *= s;
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z1 += _omega * (s - z1); // Update first filter.
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z2 += 4 * _omega * (z1 - z2); // Update second filter.
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}
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if (isnan(z1)) z1 = 0;
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if (isnan(z2)) z2 = 0;
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// Save filter state. The added constants avoid denormals.
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_z1 = z1 + 1e-20f;
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_z2 = z2 + 1e-20f;
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s = sqrtf (2.0f * z2);
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if (_flag) {
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// Display thread has read the rms value.
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_rms = s;
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_flag = false;
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} else {
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// Adjust RMS value and update maximum since last read().
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if (s > _rms) _rms = s;
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}
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}
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/* Returns highest _rms value since last call */
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float
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Kmeterdsp::read ()
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{
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float rv= _rms;
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_flag = true; // Resets _rms in next process().
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return rv;
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}
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void
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Kmeterdsp::reset ()
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{
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_z1 = _z2 = _rms = .0f;
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_flag = false;
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}
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