66 lines
1.4 KiB
C++
66 lines
1.4 KiB
C++
#include <psemek/audio/wave/karplus_strong.hpp>
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#include <psemek/audio/constants.hpp>
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#include <psemek/audio/white_noise.hpp>
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#include <psemek/random/generator.hpp>
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#include <psemek/random/uniform.hpp>
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#include <vector>
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#include <atomic>
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namespace psemek::audio
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{
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namespace
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{
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struct karplus_strong_impl
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: stream
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{
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karplus_strong_impl(float frequency)
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: buffer_(white_noise(2 * std::round(audio::frequency / frequency)))
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{}
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std::optional<std::size_t> length() const override
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{
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return std::nullopt;
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}
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std::size_t read(float * data, std::size_t sample_count) override
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{
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std::size_t const size = buffer_.size();
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for (std::size_t i = 0; i < sample_count; i += 2)
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{
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buffer_[buffer_pos_ + 0] = (buffer_[buffer_pos_ + 0] + buffer_[(buffer_pos_ + 2) % size + 0]) / 2.f;
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buffer_[buffer_pos_ + 1] = (buffer_[buffer_pos_ + 1] + buffer_[(buffer_pos_ + 2) % size + 1]) / 2.f;
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data[i + 0] = buffer_[buffer_pos_ + 0];
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data[i + 1] = buffer_[buffer_pos_ + 1];
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buffer_pos_ += 2;
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buffer_pos_ %= size;
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}
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return sample_count;
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}
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std::size_t played() const override
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{
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return played_.load();
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}
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private:
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std::vector<float> buffer_;
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std::size_t buffer_pos_{0};
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std::atomic<std::size_t> played_;
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};
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}
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stream_ptr karplus_strong(float frequency)
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{
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return std::make_shared<karplus_strong_impl>(frequency);
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}
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}
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