Introduction

In the world of audio synthesis, building interactive music applications requires efficient and flexible programming techniques. C++ coroutines, introduced in the C++20 standard, offer an elegant solution for asynchronous programming, making it easier to create real-time audio synthesis applications. In this article, we’ll explore how C++ coroutines can be leveraged to create powerful interactive music applications.

Understanding Coroutines

A coroutine is a special type of function that can be paused and resumed. It allows a program to suspend its execution and resume it later without losing its state. Coroutines are designed to provide a more structured approach to asynchronous programming, making it easier to write maintainable and readable code.

C++ Coroutines

C++20 introduces built-in support for coroutines through the co_await and co_yield keywords. This enables us to write code that suspends and resumes execution without manually managing callback functions or state machines.

Audio Synthesis with Coroutines

With the help of C++ coroutines, we can create an audio synthesis system that generates sound in real-time. Here’s a simplified example of how coroutines can be used to generate a sine wave:

#include <cmath>
#include <iostream>
#include <chrono>
#include <thread>

#include <experimental/coroutine>

using namespace std::chrono_literals;

// Coroutine that generates a sine wave
class SineWaveGenerator {
public:
    struct promise_type {
        float value;

        auto get_return_object() { return SineWaveGenerator{std::experimental::coroutine_handle<promise_type>::from_promise(*this)}; }

        auto initial_suspend() { return std::experimental::suspend_always{}; }
        auto final_suspend() noexcept { return std::experimental::suspend_always{}; }
        auto yield_value(float value) { this->value = value; return std::experimental::suspend_always{}; }
        void return_void() {}
        void unhandled_exception() {}
    };

    SineWaveGenerator(std::experimental::coroutine_handle<promise_type> handle) : handle(handle) {}

    ~SineWaveGenerator() { handle.destroy(); }

    bool next() {
        handle.resume();
        return !handle.done();
    }

    float current_value() const { return handle.promise().value; }

private:
    std::experimental::coroutine_handle<promise_type> handle;
};

// Example usage
int main() {
    SineWaveGenerator generator{SineWaveGenerator::promise_type{}.get_return_object()};
    
    while (generator.next()) {
        float sample = generator.current_value();
        // Output the sample value to the audio device or process it in any way
        std::cout << sample << std::endl;

        std::this_thread::sleep_for(10ms);
    }
    
    return 0;
}

In this example, the SineWaveGenerator coroutine generates a sine wave sample on each yield_value call. The main function iterates over the coroutine, retrieves the current value, and processes it accordingly. This approach allows us to generate sound in real-time, making it possible to create interactive music applications.

Conclusion

C++ coroutines provide an efficient and readable way to implement audio synthesis applications. By leveraging coroutines, we can build interactive music applications with real-time sound generation. With the power of C++ and coroutines, the possibilities in the realm of audio synthesis are endless.

#programming #cppcoroutines #audiosynthesis