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https://github.com/RGBCube/serenity
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59bde64ba6
Notice that we are calculating release time according to the level when the note is turned off rather than the sustain level. Naively using the sustain level gives very long release times if you turn the note off during attack, whereas this deterministically gives the same release time.
274 lines
7.6 KiB
C++
274 lines
7.6 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2019-2020, William McPherson <willmcpherson2@gmail.com>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "AudioEngine.h"
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#include <limits>
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#include <math.h>
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AudioEngine::AudioEngine()
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{
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set_sustain_impl(0);
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set_attack(0);
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set_decay(0);
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set_release(0);
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}
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AudioEngine::~AudioEngine()
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{
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}
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void AudioEngine::fill_buffer(FixedArray<Sample>& buffer)
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{
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memset(buffer.data(), 0, buffer_size);
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for (size_t i = 0; i < buffer.size(); ++i) {
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for (size_t note = 0; note < note_count; ++note) {
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switch (m_envelope[note]) {
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case Done:
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continue;
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case Attack:
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m_power[note] += m_attack_step;
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if (m_power[note] >= 1) {
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m_power[note] = 1;
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m_envelope[note] = Decay;
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}
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break;
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case Decay:
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m_power[note] -= m_decay_step;
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if (m_power[note] < m_sustain_level)
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m_power[note] = m_sustain_level;
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break;
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case Release:
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m_power[note] -= m_release_step[note];
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if (m_power[note] <= 0) {
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m_power[note] = 0;
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m_envelope[note] = Done;
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continue;
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}
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break;
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default:
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ASSERT_NOT_REACHED();
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}
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double val = 0;
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switch (m_wave) {
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case Wave::Sine:
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val = (volume * m_power[note]) * sine(note);
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break;
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case Wave::Saw:
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val = (volume * m_power[note]) * saw(note);
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break;
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case Wave::Square:
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val = (volume * m_power[note]) * square(note);
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break;
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case Wave::Triangle:
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val = (volume * m_power[note]) * triangle(note);
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break;
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case Wave::Noise:
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val = (volume * m_power[note]) * noise();
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break;
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default:
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ASSERT_NOT_REACHED();
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}
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buffer[i].left += val;
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}
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buffer[i].right = buffer[i].left;
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}
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if (m_delay) {
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if (m_delay_buffers.size() >= m_delay) {
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auto to_blend = m_delay_buffers.dequeue();
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for (size_t i = 0; i < to_blend->size(); ++i) {
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buffer[i].left += (*to_blend)[i].left * 0.333333;
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buffer[i].right += (*to_blend)[i].right * 0.333333;
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}
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}
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auto delay_buffer = make<FixedArray<Sample>>(buffer.size());
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memcpy(delay_buffer->data(), buffer.data(), buffer_size);
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m_delay_buffers.enqueue(move(delay_buffer));
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}
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if (++m_time == m_tick)
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m_time = 0;
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memcpy(m_back_buffer_ptr->data(), buffer.data(), buffer_size);
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swap(m_front_buffer_ptr, m_back_buffer_ptr);
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}
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// All of the information for these waves is on Wikipedia.
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double AudioEngine::sine(size_t note)
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{
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double pos = note_frequencies[note] / sample_rate;
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double sin_step = pos * 2 * M_PI;
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double w = sin(m_pos[note]);
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m_pos[note] += sin_step;
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return w;
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}
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double AudioEngine::saw(size_t note)
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{
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double saw_step = note_frequencies[note] / sample_rate;
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double t = m_pos[note];
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double w = (0.5 - (t - floor(t))) * 2;
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m_pos[note] += saw_step;
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return w;
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}
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double AudioEngine::square(size_t note)
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{
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double pos = note_frequencies[note] / sample_rate;
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double square_step = pos * 2 * M_PI;
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double w = sin(m_pos[note]) >= 0 ? 1 : -1;
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m_pos[note] += square_step;
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return w;
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}
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double AudioEngine::triangle(size_t note)
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{
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double triangle_step = note_frequencies[note] / sample_rate;
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double t = m_pos[note];
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double w = fabs(fmod((4 * t) + 1, 4) - 2) - 1;
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m_pos[note] += triangle_step;
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return w;
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}
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double AudioEngine::noise() const
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{
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double random_percentage = static_cast<double>(rand()) / RAND_MAX;
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double w = (random_percentage * 2) - 1;
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return w;
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}
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static inline double calculate_step(double distance, int milliseconds)
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{
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if (milliseconds == 0)
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return distance;
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constexpr double samples_per_millisecond = sample_rate / 1000.0;
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double samples = milliseconds * samples_per_millisecond;
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double step = distance / samples;
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return step;
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}
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void AudioEngine::set_note(int note, Switch switch_note)
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{
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ASSERT(note >= 0 && note < note_count);
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if (switch_note == On) {
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if (m_note_on[note] == 0) {
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m_pos[note] = 0;
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m_envelope[note] = Attack;
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}
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++m_note_on[note];
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} else {
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if (m_note_on[note] >= 1) {
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if (m_note_on[note] == 1) {
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m_release_step[note] = calculate_step(m_power[note], m_release);
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m_envelope[note] = Release;
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}
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--m_note_on[note];
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}
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}
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ASSERT(m_note_on[note] != std::numeric_limits<u8>::max());
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ASSERT(m_power[note] >= 0);
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}
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void AudioEngine::set_note_current_octave(int note, Switch switch_note)
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{
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set_note(note + octave_base(), switch_note);
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}
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void AudioEngine::set_octave(Direction direction)
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{
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if (direction == Up) {
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if (m_octave < octave_max)
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++m_octave;
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} else {
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if (m_octave > octave_min)
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--m_octave;
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}
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}
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void AudioEngine::set_wave(int wave)
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{
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ASSERT(wave >= first_wave && wave <= last_wave);
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m_wave = wave;
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}
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void AudioEngine::set_wave(Direction direction)
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{
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if (direction == Up) {
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if (++m_wave > last_wave)
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m_wave = first_wave;
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} else {
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if (--m_wave < first_wave)
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m_wave = last_wave;
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}
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}
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void AudioEngine::set_attack(int attack)
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{
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ASSERT(attack >= 0);
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m_attack = attack;
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m_attack_step = calculate_step(1, m_attack);
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}
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void AudioEngine::set_decay(int decay)
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{
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ASSERT(decay >= 0);
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m_decay = decay;
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m_decay_step = calculate_step(1 - m_sustain_level, m_decay);
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}
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void AudioEngine::set_sustain_impl(int sustain)
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{
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ASSERT(sustain >= 0);
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m_sustain = sustain;
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m_sustain_level = sustain / 1000.0;
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}
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void AudioEngine::set_sustain(int sustain)
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{
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set_sustain_impl(sustain);
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set_decay(m_decay);
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}
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void AudioEngine::set_release(int release)
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{
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ASSERT(release >= 0);
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m_release = release;
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}
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void AudioEngine::set_delay(int delay)
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{
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ASSERT(delay >= 0);
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m_delay_buffers.clear();
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m_delay = delay;
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}
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