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Piano: Make decay more accurate

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1. Make decay sample-granular rather than buffer-granular
You only have ~43 buffers per second which can make a jagged signal.

2. Calculate decay in milliseconds
Decay is supposed to be a time value.
This commit is contained in:
William McPherson 2020-02-05 01:36:30 +11:00 • committed by Andreas Kling
parent 44c81ee9db
commit 421a340572
3 changed files with 21 additions and 12 deletions
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28
Applications/Piano/AudioEngine.cpp
View file

@ -31,6 +31,7 @@
AudioEngine::AudioEngine() AudioEngine::AudioEngine()
{ {
set_decay(0);
} }
AudioEngine::~AudioEngine() AudioEngine::~AudioEngine()
@ -45,6 +46,11 @@ void AudioEngine::fill_buffer(FixedArray<Sample>& buffer)
for (size_t note = 0; note < note_count; ++note) { for (size_t note = 0; note < note_count; ++note) {
if (!m_note_on[note]) if (!m_note_on[note])
continue; continue;
m_power[note] -= m_decay_step;
if (m_power[note] < 0)
m_power[note] = 0;
double val = 0; double val = 0;
switch (m_wave) { switch (m_wave) {
case Wave::Sine: case Wave::Sine:
@ -70,16 +76,6 @@ void AudioEngine::fill_buffer(FixedArray<Sample>& buffer)
buffer[i].right = buffer[i].left; buffer[i].right = buffer[i].left;
} }
if (m_decay) {
for (size_t note = 0; note < note_count; ++note) {
if (m_note_on[note]) {
m_power[note] -= m_decay / 100.0;
if (m_power[note] < 0)
m_power[note] = 0;
}
}
}
if (m_delay) { if (m_delay) {
if (m_delay_buffers.size() >= m_delay) { if (m_delay_buffers.size() >= m_delay) {
auto to_blend = m_delay_buffers.dequeue(); auto to_blend = m_delay_buffers.dequeue();
@ -201,10 +197,22 @@ void AudioEngine::set_wave(Direction direction)
} }
} }
static inline double calculate_step(double distance, int milliseconds)
{
if (milliseconds == 0)
return distance;
constexpr double samples_per_millisecond = sample_rate / 1000.0;
double samples = milliseconds * samples_per_millisecond;
double step = distance / samples;
return step;
}
void AudioEngine::set_decay(int decay) void AudioEngine::set_decay(int decay)
{ {
ASSERT(decay >= 0); ASSERT(decay >= 0);
m_decay = decay; m_decay = decay;
m_decay_step = calculate_step(1, m_decay);
} }
void AudioEngine::set_delay(int delay) void AudioEngine::set_delay(int delay)

3
Applications/Piano/AudioEngine.h
View file

@ -77,7 +77,8 @@ private:
int m_octave { 4 }; int m_octave { 4 };
int m_wave { first_wave }; int m_wave { first_wave };
int m_decay { 0 }; int m_decay;
double m_decay_step;
int m_delay { 0 }; int m_delay { 0 };
int m_time { 0 }; int m_time { 0 };

2
Applications/Piano/KnobsWidget.cpp
View file

@ -91,7 +91,7 @@ KnobsWidget::KnobsWidget(GUI::Widget* parent, AudioEngine& audio_engine, MainWid
m_wave_value->set_text(wave_strings[new_wave]); m_wave_value->set_text(wave_strings[new_wave]);
}; };
constexpr int max_decay = 20; constexpr int max_decay = 1000;
m_decay_knob = GUI::Slider::construct(Orientation::Vertical, m_knobs_container); m_decay_knob = GUI::Slider::construct(Orientation::Vertical, m_knobs_container);
m_decay_knob->set_range(0, max_decay); m_decay_knob->set_range(0, max_decay);
m_decay_knob->set_value(max_decay - m_audio_engine.decay()); m_decay_knob->set_value(max_decay - m_audio_engine.decay());