When it comes to audio effects processing, delay and reverb are two of the most commonly used effects. They can add depth, space, and ambience to audio signals, whether it’s a musical recording, a podcast, or a game.

In this blog post, we will explore how to implement delay and reverb effects using C++.

Delay Effect

The delay effect creates an echo-like sound by repeating the input signal after a certain delay period. The basic algorithm for a delay effect involves storing a buffer of the input signal and playing it back after a specified amount of time. Here’s an example code snippet:

const int bufferSize = 44100; // buffer size in samples
float buffer[bufferSize]; // buffer to store input signal

void delayEffect(float *input, float *output, int length, float delayTime, float feedback) {
    int delaySamples = int(delayTime * sampleRate); // convert delay time to samples

    for (int i = 0; i < length; i++) {
        output[i] = input[i] + feedback * buffer[i - delaySamples];
        buffer[i] = input[i];
    }
}

In the above code, input is the input signal, output is the output signal, length is the length of the signal in samples, delayTime is the delay time in seconds, and feedback controls the amount of feedback in the delay effect.

Reverb Effect

The reverb effect simulates the acoustic properties of different spaces, such as rooms, halls, or stadiums. It adds a series of delayed and attenuated reflections to the input signal to create a sense of spaciousness. Implementing a reverb effect can be more complex compared to a delay effect, as it involves multiple delay lines and feedback loops.

Here’s a simplified example code snippet that demonstrates a basic reverb effect using a simple feedback delay network (FDN):

const int numDelayLines = 4; // number of delay lines
const float delays[numDelayLines] = {0.02, 0.035, 0.045, 0.05}; // delay times for each line
const float feedbacks[numDelayLines] = {0.5, 0.3, 0.2, 0.1}; // feedback gains for each line

float buffer[numDelayLines][bufferSize]; // buffer for each delay line

void reverbEffect(float *input, float *output, int length) {
    for (int i = 0; i < length; i++) {
        float sample = input[i];

        for (int j = 0; j < numDelayLines; j++) {
            int delaySamples = int(delays[j] * sampleRate);
            sample += feedbacks[j] * buffer[j][i - delaySamples];
            buffer[j][i] = sample;
        }

        output[i] = sample;
    }
}

In the code above, delays and feedbacks define the delay times and feedback gains for each delay line, respectively. The buffer array stores the delayed samples for each delay line.

These examples provide a starting point for implementing delay and reverb effects in C++. You can further enhance these effects by incorporating additional features such as filtering, modulation, and more complex algorithms.

Implementing audio effects in C++ allows for fine-grained control and customization, making it a popular choice for audio processing applications. Experiment with different parameters and algorithms to achieve the desired sound and explore more advanced techniques in audio effect processing.

#programming #audioeffects