67 lines
1.3 KiB
C++
67 lines
1.3 KiB
C++
#include <psemek/audio/effect/echo.hpp>
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#include <vector>
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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 echo_impl
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: stream
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{
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echo_impl(stream_ptr stream, duration delay, float gain)
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: stream_(std::move(stream))
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, buffer_(2 * std::max(1l, delay.samples()), 0.f)
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, gain_(gain)
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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(util::span<float> samples) override
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{
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auto count = stream_->read(samples);
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for (std::size_t i = 0; i < count; ++i)
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{
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float output = buffer_[buffer_pos_];
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buffer_[buffer_pos_] = samples[i] + buffer_[buffer_pos_] * gain_;
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samples[i] = output;
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++buffer_pos_;
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buffer_pos_ %= buffer_.size();
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}
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for (std::size_t i = count; i < samples.size(); ++i)
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{
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samples[i] = buffer_[buffer_pos_];
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buffer_[buffer_pos_] = buffer_[buffer_pos_] * gain_;
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++buffer_pos_;
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buffer_pos_ %= buffer_.size();
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}
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return samples.size();
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}
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std::size_t played() const override
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{
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return stream_->played();
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}
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private:
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stream_ptr stream_;
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std::vector<float> buffer_;
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std::size_t buffer_pos_ = 0;
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float gain_;
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};
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}
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stream_ptr echo(stream_ptr stream, duration delay, float gain)
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{
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return std::make_shared<echo_impl>(std::move(stream), delay, gain);
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}
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}
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