To get started, we need to define the equalization filter coefficients which determine how the different frequency components of the input signal will be adjusted. These coefficients can be obtained through various methods such as using an equalizer design algorithm or manually specifying them based on desired frequency response.

First, let’s define a struct to hold the filter coefficients:

struct EqualizationCoefficients {
    double gain;    // overall gain adjustment
    double* gains;  // gain adjustments for individual frequency bands
};

The gain member variable represents the overall gain adjustment, and gains is an array that holds the gain adjustments for each frequency band.

Next, we can implement the equalization function that takes in an input signal and applies the equalization filter:

void equalizeSignal(double* inputSignal, int signalLength, EqualizationCoefficients& eqCoefficients) {
    // Apply overall gain adjustment
    for (int i = 0; i < signalLength; i++) {
        inputSignal[i] *= eqCoefficients.gain;
    }
    
    // Apply individual gain adjustments for each frequency band
    for (int i = 0; i < signalLength; i++) {
        inputSignal[i] *= eqCoefficients.gains[i % numFrequencyBands];
    }
}

In this implementation, we first apply the overall gain adjustment to the entire signal. Then, we iterate through the signal and apply the individual gain adjustments for each frequency band. The % operator is used to cycle through the gain adjustments in a repeating pattern.

To use this equalization function, you would need to provide an input signal, the length of the signal, and the equalization coefficients. Here’s an example usage:

int main() {
    // Define input signal
    double inputSignal[] = {0.1, 0.2, 0.3, 0.4, 0.5};

    // Define equalization coefficients
    EqualizationCoefficients eqCoefficients;
    eqCoefficients.gain = 1.5;
    double gains[] = {1.0, 0.8, 1.2}; // Adjustments for 3 frequency bands
    eqCoefficients.gains = gains;

    // Apply equalization
    equalizeSignal(inputSignal, 5, eqCoefficients);

    // Display equalized signal
    for (int i = 0; i < 5; i++) {
        std::cout << inputSignal[i] << " ";
    }

    return 0;
}

In this example, we define an input signal and equalization coefficients. We then call the equalizeSignal function to apply the equalization. Finally, we display the equalized signal using std::cout.

Implementing equalization in C++ allows you to customize the frequency response of your audio signals or any other forms of digital signals. This technique is widely used in audio processing applications, multimedia systems, and communication systems to achieve desired sound characteristics.

#programming #audio #cplusplus