Method spectralMag

src/extended/SpectralMonitorNode.cpp:201–230

}

void SpectralMonitorNode::spectralMag(std::vector<float> & result)
{
    std::vector<float> window;

    {
        std::lock_guard<std::recursive_mutex> lock(internalNode->magMutex);
        window.swap(internalNode->buffer);
        internalNode->setWindowSize(internalNode->windowSize->valueUint32());
    }

    // http://www.ni.com/white-paper/4844/en/
    ApplyWindowFunctionInplace(WindowFunction::blackman, window.data(), static_cast<int>(window.size()));
    internalNode->fft->forward(window);

    // similar to cinder audio2 Scope object, although Scope smooths spectral samples frame by frame
    // remove nyquist component - the first imaginary component
    window[1] = 0.0f;

    // compute normalized magnitude spectrum
    /// @TODO @tofix - break this into vector Cartesian -> polar and then vector lowpass. skip lowpass if smoothing factor is very small
    const float kMagScale = 1.0f;  /// detail->windowSize;
    for (int i = 0; i < window.size(); i += 2)
    {
        float re = window[i];
        float im = window[i + 1];
        window[i / 2] = sqrt(re * re + im * im) * kMagScale;
    }

    result.swap(window);
}

void SpectralMonitorNode::windowSize(unsigned int ws)
{