Line data    Source code

       1              : /*
       2              :  * SPDX-License-Identifier: GPL-3.0-only
       3              :  * MuseScore-CLA-applies
       4              :  *
       5              :  * MuseScore Studio
       6              :  * Music Composition & Notation
       7              :  *
       8              :  * Copyright (C) 2021 MuseScore Limited and others
       9              :  *
      10              :  * This program is free software: you can redistribute it and/or modify
      11              :  * it under the terms of the GNU General Public License version 3 as
      12              :  * published by the Free Software Foundation.
      13              :  *
      14              :  * This program is distributed in the hope that it will be useful,
      15              :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      16              :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      17              :  * GNU General Public License for more details.
      18              :  *
      19              :  * You should have received a copy of the GNU General Public License
      20              :  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
      21              :  */
      22              : #include "equaliser.h"
      23              : 
      24              : #include <cmath>
      25              : 
      26              : #include "log.h"
      27              : 
      28              : using namespace muse::audio;
      29              : using namespace muse::audio::fx;
      30              : 
      31            0 : void Equaliser::setOutputSpec(const OutputSpec& spec)
      32              : {
      33            0 :     m_outputSpec = spec;
      34            0 :     calculate();
      35            0 : }
      36              : 
      37            0 : bool Equaliser::active() const
      38              : {
      39            0 :     return m_active;
      40              : }
      41              : 
      42            0 : void Equaliser::setActive(bool active)
      43              : {
      44            0 :     m_active = active;
      45            0 : }
      46              : 
      47            0 : void Equaliser::setMode(const ProcessMode)
      48              : {
      49            0 : }
      50              : 
      51            0 : bool Equaliser::shouldProcessDuringSilence() const
      52              : {
      53            0 :     return false;
      54              : }
      55              : 
      56            0 : void Equaliser::process(float* buffer, samples_t sampleCount, samples_t)
      57              : {
      58            0 :     for (samples_t i = 0; i < sampleCount; ++i) {
      59            0 :         m_x[2] = m_x[1];
      60            0 :         m_x[1] = m_x[0];
      61            0 :         m_x[0] = buffer[i];
      62              : 
      63            0 :         m_y[2] = m_y[1];
      64            0 :         m_y[1] = m_y[0];
      65            0 :         m_y[0] = (m_b[2] * m_x[2] + m_b[1] * m_x[1] + m_b[0] * m_x[0] - m_a[1] * m_y[1] - m_a[2] * m_y[2]) / m_a[0];
      66              : 
      67            0 :         buffer[i] = m_y[0];
      68              :     }
      69            0 : }
      70              : 
      71            0 : void Equaliser::calculate()
      72              : {
      73            0 :     if (!m_outputSpec.sampleRate) {
      74            0 :         return;
      75              :     }
      76            0 :     float a = std::pow(10.f, m_gain / 40.f);
      77            0 :     float w0 = 2 * M_PI * m_frequency / m_outputSpec.sampleRate;
      78            0 :     float alpha = std::sin(w0) * a / (2 * m_q);
      79              : 
      80            0 :     m_b[0] = 1 + alpha * a;
      81            0 :     m_b[1] = -2 * std::cos(w0);
      82            0 :     m_b[2] = 1 - alpha * a;
      83              : 
      84            0 :     m_a[0] = 1 + alpha / a;
      85            0 :     m_a[1] = -2 * std::cos(w0);
      86            0 :     m_a[2] = 1 - alpha / a;
      87              : }
      88              : 
      89            0 : void Equaliser::setFrequency(float value)
      90              : {
      91            0 :     m_frequency = value;
      92            0 :     calculate();
      93            0 : }
      94              : 
      95            0 : void Equaliser::setGain(float value)
      96              : {
      97            0 :     m_gain = value;
      98            0 :     calculate();
      99            0 : }
     100              : 
     101            0 : void Equaliser::setQ(float value)
     102              : {
     103            0 :     m_q = value;
     104            0 :     calculate();
     105            0 : }