static Matrixcf stft()

in StreamingASR/StreamingASR/app/src/main/cpp/librosa/librosa.h [78:95]

• 14 lines of code
• 3 McCabe index (conditional complexity)

static Matrixcf stft(Vectorf &x, int n_fft, int n_hop, const std::string &win, bool center, const std::string &mode){
  // hanning
  Vectorf window = 0.5*(1.f-(Vectorf::LinSpaced(n_fft, 0.f, static_cast<float>(n_fft-1))*2.f*M_PI/n_fft).array().cos());

  int pad_len = center ? n_fft / 2 : 0;
  Vectorf x_paded = pad(x, pad_len, pad_len, mode, 0.f);

  int n_f = n_fft/2+1;
  int n_frames = 1+(x_paded.size()-n_fft) / n_hop;
  Matrixcf X(n_frames, n_fft);
  Eigen::FFT<float> fft;

  for (int i = 0; i < n_frames; ++i){
    Vectorf x_frame = window.array()*x_paded.segment(i*n_hop, n_fft).array();
    X.row(i) = fft.fwd(x_frame);
  }
  return X.leftCols(n_f);
}