attempt to improve FFT zoom resolution

src/visual/WaterfallCanvas.cpp

@@ -36,7 +36,7 @@ wxEND_EVENT_TABLE()
 WaterfallCanvas::WaterfallCanvas(wxWindow *parent, int *attribList) :
         InteractiveCanvas(parent, attribList), spectrumCanvas(NULL), dragState(WF_DRAG_NONE), nextDragState(WF_DRAG_NONE), fft_size(0), waterfall_lines(
                 0), plan(
-        NULL), in(NULL), out(NULL), resampler(NULL), resamplerRatio(0), lastInputBandwidth(0), zoom(1), mouseZoom(1), otherWaterfallCanvas(NULL), polling(true) {
+        NULL), in(NULL), out(NULL), resampler(NULL), resamplerRatio(0), lastInputBandwidth(0), zoom(1), mouseZoom(1), otherWaterfallCanvas(NULL), polling(true), last_data_size(0), fft_in_data(NULL), fft_last_data(NULL) {
 
     glContext = new WaterfallContext(this, &wxGetApp().GetContext(this));
 
@@ -64,6 +64,14 @@ void WaterfallCanvas::setup(int fft_size_in, int waterfall_lines_in) {
         free(in);
     }
     in = (fftwf_complex*) fftwf_malloc(sizeof(fftwf_complex) * fft_size);
+    if (fft_in_data) {
+        free(fft_in_data);
+    }
+    fft_in_data = (fftwf_complex*) fftwf_malloc(sizeof(fftwf_complex) * fft_size);
+    if (fft_last_data) {
+        free(fft_last_data);
+    }
+    fft_last_data = (fftwf_complex*) fftwf_malloc(sizeof(fftwf_complex) * fft_size);
     if (out) {
         free(out);
     }
@@ -394,6 +402,8 @@ void WaterfallCanvas::setData(DemodulatorThreadIQData *input) {
             spectrum_points.resize(fft_size * 2);
         }
 
+        unsigned int num_written;
+
         if (isView) {
             if (!input->frequency || !input->sampleRate) {
                 return;
@@ -447,45 +457,69 @@ void WaterfallCanvas::setData(DemodulatorThreadIQData *input) {
                 resampleBuffer.resize(out_size);
             }
 
-            unsigned int num_written;
             msresamp_crcf_execute(resampler, &shiftBuffer[0], input->data.size(), &resampleBuffer[0], &num_written);
 
             resampleBuffer.resize(fft_size);
 
             if (num_written < fft_size) {
                 for (int i = 0; i < num_written; i++) {
-                    in[i][0] = resampleBuffer[i].real;
+                    fft_in_data[i][0] = resampleBuffer[i].real;
-                    in[i][1] = resampleBuffer[i].imag;
+                    fft_in_data[i][1] = resampleBuffer[i].imag;
                 }
                 for (int i = num_written; i < fft_size; i++) {
-                    in[i][0] = 0;
+                    fft_in_data[i][0] = 0;
-                    in[i][1] = 0;
+                    fft_in_data[i][1] = 0;
                 }
             } else {
                 for (int i = 0; i < fft_size; i++) {
-                    in[i][0] = resampleBuffer[i].real;
+                    fft_in_data[i][0] = resampleBuffer[i].real;
-                    in[i][1] = resampleBuffer[i].imag;
+                    fft_in_data[i][1] = resampleBuffer[i].imag;
                 }
             }
         } else {
-
+            num_written = data->size();
             if (data->size() < fft_size) {
                 for (int i = 0, iMax = data->size(); i < iMax; i++) {
-                    in[i][0] = (*data)[i].real;
+                    fft_in_data[i][0] = (*data)[i].real;
-                    in[i][1] = (*data)[i].imag;
+                    fft_in_data[i][1] = (*data)[i].imag;
                 }
                 for (int i = data->size(); i < fft_size; i++) {
-                    in[i][0] = 0;
+                    fft_in_data[i][0] = 0;
-                    in[i][1] = 0;
+                    fft_in_data[i][1] = 0;
                 }
             } else {
                 for (int i = 0; i < fft_size; i++) {
-                    in[i][0] = (*data)[i].real;
+                    fft_in_data[i][0] = (*data)[i].real;
-                    in[i][1] = (*data)[i].imag;
+                    fft_in_data[i][1] = (*data)[i].imag;
                 }
             }
         }
 
+        bool execute = false;
+
+        if (num_written >= fft_size) {
+            execute = true;
+            memcpy(in, fft_in_data, sizeof(fftwf_complex) * fft_size * sizeof(fftwf_complex));
+            memcpy(fft_last_data, in, fft_size * sizeof(fftwf_complex));
+
+        } else {
+            if (last_data_size + num_written < fft_size) { // priming
+                unsigned int num_copy = fft_size;
+                num_copy = fft_size - last_data_size;
+                if (num_written > num_copy) {
+                    num_copy = num_written;
+                }
+                memcpy(fft_last_data, fft_in_data, num_copy * sizeof(fftwf_complex));
+                last_data_size += num_copy;
+            } else {
+                unsigned int num_last = (fft_size - num_written);
+                memcpy(in, fft_last_data + (last_data_size - num_last), num_last * sizeof(fftwf_complex));
+                memcpy(in + num_last, fft_in_data, num_written * sizeof(fftwf_complex));
+                memcpy(fft_last_data, in, fft_size * sizeof(fftwf_complex));
+            }
+        }
+
+        if (execute) {
             fftwf_execute(plan);
 
             float fft_ceil = 0, fft_floor = 1;
@@ -548,6 +582,7 @@ void WaterfallCanvas::setData(DemodulatorThreadIQData *input) {
             }
         }
     }
+}
 
 void WaterfallCanvas::OnIdle(wxIdleEvent &event) {
     Refresh(false);

src/visual/WaterfallCanvas.h

@@ -56,7 +56,8 @@ private:
     WaterfallCanvas *otherWaterfallCanvas;
     bool polling;
 
-    fftwf_complex *in, *out;
+    fftwf_complex *in, *out, *fft_in_data, *fft_last_data;
+    unsigned int last_data_size;
     fftwf_plan plan;
 
     float fft_ceil_ma, fft_ceil_maa;
@@ -84,6 +85,8 @@ private:
 
     std::vector<liquid_float_complex> shiftBuffer;
     std::vector<liquid_float_complex> resampleBuffer;
+
+
     // event table
 wxDECLARE_EVENT_TABLE();
 };