lisyarus/psemek
1
0
Fork 1
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Reimplement basic waveforms using a complex oscillator

Browse source
This commit is contained in:
Nikita Lisitsa 2022-10-05 20:48:39 +03:00
parent 051e812358
commit 65f71e54a8
6 changed files with 51 additions and 20 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

34
libs/audio/include/psemek/audio/oscillator.hpp Normal file
View file

@ -0,0 +1,34 @@
#pragma once
#include <psemek/audio/constants.hpp>
#include <psemek/geom/constants.hpp>
#include <complex>
namespace psemek::audio
{
struct oscillator
{
oscillator(float frequency)
: m_(std::exp(std::complex<float>{0.f, 2.f * geom::pi * frequency * inv_frequency}))
{}
std::complex<float> phase() const
{
return phase_;
}
std::complex<float> next()
{
phase_ *= m_;
phase_ /= std::abs(phase_);
return phase_;
}
private:
std::complex<float> phase_{1.f, 0.f};
std::complex<float> m_;
};
}

5
libs/audio/include/psemek/audio/wave/generator.hpp
View file

@ -12,7 +12,6 @@ namespace psemek::audio
{
generator_stream(Func func)
: func_(std::move(func))
, phase_(0.f)
{}
std::size_t read(float * data, std::size_t sample_count) override
@ -20,17 +19,15 @@ namespace psemek::audio
auto end = data + sample_count;
for (auto p = data; p != end;)
{
float v = func_(phase_);
float v = func_();
*p++ = v;
*p++ = v;
phase_ += inv_frequency;
}
return sample_count;
}
private:
Func func_;
float phase_;
};
}

9
libs/audio/source/wave/sawtooth.cpp
View file

@ -1,7 +1,8 @@
#include <psemek/audio/wave/sawtooth.hpp>
#include <psemek/audio/wave/generator.hpp>
#include <psemek/geom/math.hpp>
#include <psemek/audio/oscillator.hpp>
#include <psemek/util/to_shared.hpp>
#include <psemek/log/log.hpp>
#include <cmath>
@ -10,9 +11,9 @@ namespace psemek::audio
stream_ptr sawtooth_wave(float frequency)
{
auto func = [frequency](float t){
t *= frequency;
return (t - std::floor(t)) * 2.f - 1.f;
auto func = [o = oscillator{frequency}]() mutable {
auto z = o.next();
return (2.f / geom::pi) * (- std::atan2(z.real() + 1.f, z.imag()));
};
return util::to_shared(generator_stream(func));

9
libs/audio/source/wave/sine.cpp
View file

@ -1,19 +1,18 @@
#include <psemek/audio/wave/sine.hpp>
#include <psemek/audio/wave/generator.hpp>
#include <psemek/geom/math.hpp>
#include <psemek/audio/oscillator.hpp>
#include <psemek/util/to_shared.hpp>
#include <cmath>
#include <complex>
namespace psemek::audio
{
stream_ptr sine_wave(float frequency)
{
float angular_frequency = frequency * 2.f * geom::pi;
auto func = [angular_frequency](float t){
return std::sin(angular_frequency * t);
auto func = [o = oscillator{frequency}]() mutable {
return o.next().imag();
};
return util::to_shared(generator_stream(func));

7
libs/audio/source/wave/square.cpp
View file

@ -1,6 +1,6 @@
#include <psemek/audio/wave/square.hpp>
#include <psemek/audio/wave/generator.hpp>
#include <psemek/geom/math.hpp>
#include <psemek/audio/oscillator.hpp>
#include <psemek/util/to_shared.hpp>
#include <cmath>
@ -10,9 +10,8 @@ namespace psemek::audio
stream_ptr square_wave(float frequency)
{
auto func = [frequency](float t){
t *= frequency;
return (t - std::floor(t)) < 0.5f ? 1.f : -1.f;
auto func = [o = oscillator{frequency}]() mutable {
return o.next().imag() > 0.f ? 1.f : -1.f;
};
return util::to_shared(generator_stream(func));

7
libs/audio/source/wave/triangle.cpp
View file

@ -1,6 +1,6 @@
#include <psemek/audio/wave/triangle.hpp>
#include <psemek/audio/wave/generator.hpp>
#include <psemek/geom/math.hpp>
#include <psemek/audio/oscillator.hpp>
#include <psemek/util/to_shared.hpp>
#include <cmath>
@ -10,8 +10,9 @@ namespace psemek::audio
stream_ptr triangle_wave(float frequency)
{
auto func = [frequency](float t){
t *= frequency;
auto func = [o = oscillator{frequency}]() mutable {
auto const z = o.next();
float const t = 0.5f * std::atan2(z.imag(), z.real()) / (geom::pi) + 0.5f;
return 4.f * std::abs(t - std::floor(t + 0.5f)) - 1.f;
};