X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=gtk2_ardour%2Ffft.cc;h=a4e34bf2aafedbb56116c372772ef017c2320506;hb=20ea90a186748f34061fec323faa74f084c7937c;hp=eda1a96e3f6c601b6cad76fdd5d80cc15d2db969;hpb=1bca6b5c74064b9e8a6f70b45fb1c04a95534d30;p=ardour.git

diff --git a/gtk2_ardour/fft.cc b/gtk2_ardour/fft.cc
index eda1a96e3f..a4e34bf2aa 100644
--- a/gtk2_ardour/fft.cc
+++ b/gtk2_ardour/fft.cc
@@ -23,10 +23,13 @@
 #include <string.h>
 #include <math.h>
 
+using namespace GTKArdour;
+
 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);
 
@@ -45,17 +48,24 @@ FFT::reset()
 {
 	memset(_power_at_bin, 0, sizeof(float) * _data_size);
 	memset(_phase_at_bin, 0, sizeof(float) * _data_size);
-	
+
 	_iterations = 0;
 }
 
 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];
@@ -66,11 +76,11 @@ FFT::analyze(ARDOUR::Sample *input)
 
 #define Re (_fftOutput[i])
 #define Im (_fftOutput[_window_size-i])
-       	for (uint32_t i=1; i < _data_size - 1; i++) { 
+       	for (uint32_t i=1; i < _data_size - 1; i++) {
 
 		power = (Re * Re) + (Im * Im);
 		phase = atanf(Im / Re);
-	
+
 		if (Re < 0.0 && Im > 0.0) {
 			phase += M_PI;
 		} else if (Re < 0.0 && Im < 0.0) {
@@ -88,7 +98,7 @@ void
 FFT::calculate()
 {
 	if (_iterations > 1) {
-	       	for (uint32_t i=0; i < _data_size - 1; i++) { 
+	       	for (uint32_t i=0; i < _data_size - 1; i++) {
 			_power_at_bin[i] /= (float)_iterations;
 			_phase_at_bin[i] /= (float)_iterations;
 		}
@@ -96,9 +106,37 @@ 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);