FFT Test

fftTest.cpp

void FFTTest() {
    AudioFile<float> audioFile, audioFileReference, audioFileResult;
    string filename = "../" + std::string("test1mono") + ".wav";
    string filenameResult = "../" + std::string("fftResult") + ".wav";
    audioFile.load(filename);

    using namespace SMP;

    FormantFFTProcessor m_fftProcessor;

    // Prepare output vector
    std::vector<float> output_samples(audioFile.getNumSamplesPerChannel(), 0.0f);

    // Iterate over the input in chunks of FORMANT_TIME_DOMAIN_FFT_LENGTH samples
    for (size_t i = 0; i < audioFile.getNumSamplesPerChannel(); i += FORMANT_TIME_DOMAIN_FFT_LENGTH) {
        // Prepare the chunk
        std::vector<float, FFTAllocator> chunk(FORMANT_TIME_DOMAIN_FFT_LENGTH, 0.0f);
        for (size_t j = 0; j < FORMANT_TIME_DOMAIN_FFT_LENGTH; ++j) {
            if (i + j < audioFile.getNumSamplesPerChannel()) {
                chunk[j] = audioFile.samples[0][i + j];
#ifdef USE_ACCELERATE_FFT
                chunk[j] *= 0.5f;
#elif defined(USE_AV_FFT)
                chunk[j] *= 2.0f;
#endif
            }
        }

        // Prepare complex vectors for FFT
        //std::vector<ComplexType> dft(FORMANT_TIME_DOMAIN_FFT_LENGTH, ComplexType{});
        ARRAY_WRAPPER<SMP::ComplexType, FORMANT_FREQ_DOMAIN_FFT_LENGTH> dft_transfer{SMP::ComplexType{}};

        // Apply forward FFT
        m_fftProcessor.processForwardFFT(chunk, dft_transfer);

        // Apply inverse FFT
        m_fftProcessor.processInverseFFT(dft_transfer, chunk);

        // Apply scaling
        float norm_factor = 1.0 / FORMANT_TIME_DOMAIN_FFT_LENGTH;
        for (float &sample : chunk) {
            sample *= norm_factor;
        }

        // Save the chunk into the output vector
        for (size_t j = 0; j < FORMANT_TIME_DOMAIN_FFT_LENGTH; ++j) {
            if (i + j < output_samples.size()) {
                output_samples[i + j] = chunk[j];
            }
        }
    }

    // Replace input samples with output samples
    audioFile.samples[0] = output_samples;

    audioFile.save(filenameResult);
}