diff options
Diffstat (limited to 'gtk2_ardour/fft.cc')
-rw-r--r-- | gtk2_ardour/fft.cc | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/gtk2_ardour/fft.cc b/gtk2_ardour/fft.cc index eda1a96e3f..f78a1e94ad 100644 --- a/gtk2_ardour/fft.cc +++ b/gtk2_ardour/fft.cc @@ -26,7 +26,8 @@ FFT::FFT(uint32_t windowSize) : _window_size(windowSize), _data_size(_window_size/2), - _iterations(0) + _iterations(0), + _hann_window(0) { _fftInput = (float *) fftwf_malloc(sizeof(float) * _window_size); @@ -50,12 +51,19 @@ FFT::reset() } void -FFT::analyze(ARDOUR::Sample *input) +FFT::analyze(ARDOUR::Sample *input, WindowingType windowing_type) { _iterations++; memcpy(_fftInput, input, sizeof(float) * _window_size); + if (windowing_type == HANN) { + float *window = get_hann_window(); + for (uint32_t i = 0; i < _window_size; i++) { + _fftInput[i] *= window[i]; + } + } + fftwf_execute(_plan); _power_at_bin[0] += _fftOutput[0] * _fftOutput[0]; @@ -96,9 +104,37 @@ FFT::calculate() } } +float * +FFT::get_hann_window() +{ + if (_hann_window) + return _hann_window; + + + _hann_window = (float *) malloc(sizeof(float) * _window_size); + + double sum = 0.0; + + for (uint32_t i=0; i < _window_size; i++) { + _hann_window[i]=0.81f * ( 0.5f - (0.5f * (float) cos(2.0f * M_PI * (float)i / (float)(_window_size)))); + sum += _hann_window[i]; + } + + double isum = 1.0 / sum; + + for (uint32_t i=0; i < _window_size; i++) { + _hann_window[i] *= isum; + } + + return _hann_window; +} + FFT::~FFT() { + if (_hann_window) { + free(_hann_window); + } fftwf_destroy_plan(_plan); free(_power_at_bin); free(_phase_at_bin); |