process_spectral_windows()

template<typename ProcessorFunc >

std::vector< double > MayaFlux::Yantra::process_spectral_windows	(	std::span< double >	data,
		uint32_t	window_size,
		uint32_t	hop_size,
		ProcessorFunc &&	processor
	)

Common spectral processing helper to eliminate code duplication.

Template Parameters

ProcessorFunc

Function type for spectral processing

Parameters

data	Input data span
window_size	Size of analysis window
hop_size	Hop size between windows
processor	Function to process spectrum in each window

Returns

Processed audio data

Definition at line 44 of file SpectralHelper.hpp.

{
    const size_t num_windows = (data.size() >= window_size) ? (data.size() - window_size) / hop_size + 1 : 0;
 
    if (num_windows == 0) {
        return { data.begin(), data.end() };
    }
 
    std::vector<double> output(data.size(), 0.0);
 
    auto hann_window = Nodes::Generator::generate_window(window_size, Nodes::Generator::WindowType::HANNING);
 
    Eigen::FFT<double> fft;
 
    auto window_indices = std::views::iota(size_t { 0 }, num_windows);
 
    std::ranges::for_each(window_indices, [&](size_t win) {
        size_t start_idx = win * hop_size;
        auto window_data = data.subspan(start_idx,
            std::min(static_cast<size_t>(window_size), data.size() - start_idx));
 
        Eigen::VectorXd windowed = Eigen::VectorXd::Zero(static_cast<Eigen::Index>(window_size));
        const size_t actual_size = std::min(window_data.size(), hann_window.size());
 
        for (size_t j = 0; j < actual_size; ++j) {
            windowed(static_cast<Eigen::Index>(j)) = window_data[j] * hann_window[j];
        }
 
        Eigen::VectorXcd spectrum;
        fft.fwd(spectrum, windowed);
 
        std::forward<ProcessorFunc>(processor)(spectrum, win);
 
        Eigen::VectorXd result;
        fft.inv(result, spectrum);
 
        for (size_t i = 0; i < static_cast<size_t>(result.size()) && start_idx + i < output.size(); ++i) {
            output[start_idx + i] += result[static_cast<Eigen::Index>(i)];
        }
    });
 
    return output;
}

References MayaFlux::Nodes::Generator::generate_window(), and MayaFlux::Nodes::Generator::HANNING.

Referenced by MayaFlux::Yantra::SpectralTransformer< InputType, OutputType >::transform_implementation(), transform_pitch_shift(), transform_pitch_shift(), transform_spectral_filter(), transform_spectral_filter(), transform_spectral_invert(), and transform_spectral_invert().

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