Set empty images to all blank since uninitialized pixels cause problems with some renders

apps/flowgraphs/satnogs_sstv_pd120_demod.py

@@ -54,6 +54,7 @@ class satnogs_sstv_pd120_demod(gr.top_block):
         ##################################################
         # Variables
         ##################################################
+        self.sstv_low_pass = sstv_low_pass = firdes.low_pass(1.0, 4*4160*4 , 1e3,2e3, firdes.WIN_HAMMING, 6.76)
         self.intermediate_samp_rate = intermediate_samp_rate = int(4*4160*4 / 5)
         self.audio_samp_rate = audio_samp_rate = 48000
 
@@ -198,7 +199,7 @@ class satnogs_sstv_pd120_demod(gr.top_block):
                 firdes.WIN_HAMMING,
                 6.76))
         self.hilbert_fc_0 = filter.hilbert_fc(65, firdes.WIN_HAMMING, 6.76)
-        self.freq_xlating_fir_filter_xxx_0_0 = filter.freq_xlating_fir_filter_ccc(5, [63], 1750, (4*4160*4 ))
+        self.freq_xlating_fir_filter_xxx_0_0 = filter.freq_xlating_fir_filter_ccc(5, sstv_low_pass, 1750, (4*4160*4 ))
         self.analog_wfm_rcv_0 = analog.wfm_rcv(
         	quad_rate=4*4160*4,
         	audio_decimation=1,
@@ -349,6 +350,13 @@ class satnogs_sstv_pd120_demod(gr.top_block):
     def set_waterfall_file_path(self, waterfall_file_path):
         self.waterfall_file_path = waterfall_file_path
 
+    def get_sstv_low_pass(self):
+        return self.sstv_low_pass
+
+    def set_sstv_low_pass(self, sstv_low_pass):
+        self.sstv_low_pass = sstv_low_pass
+        self.freq_xlating_fir_filter_xxx_0_0.set_taps(self.sstv_low_pass)
+
     def get_intermediate_samp_rate(self):
         return self.intermediate_samp_rate
 

lib/sstv_pd120_sink_impl.cc

@@ -67,7 +67,9 @@ sstv_pd120_sink_impl::sstv_pd120_sink_impl(const char *filename_png)
 {
   set_history(sync_length);
   d_line = new float[line_length];
+
   d_image = png::image<png::rgb_pixel>(image_width, image_height);
+  blank_image();
 }
 
 /*
@@ -179,6 +181,18 @@ sstv_pd120_sink_impl::render_line()
     d_image_y = 0;
     d_initial_sync = true;
     d_num_image++;
+    blank_image();
+  }
+}
+
+void
+sstv_pd120_sink_impl::blank_image()
+{
+  std::cout << "Blanking Image" << std::endl;
+  for (size_t y = 0; y < image_height; y++) {
+    for (size_t x = 0; x < image_width; x++) {
+      d_image.set_pixel(x, y, png::rgb_pixel(0, 0, 0));
+    }
   }
 }
 

lib/sstv_pd120_sink_impl.h

@@ -49,6 +49,7 @@ private:
   bool is_sync(size_t pos, const float *samples);
 
   void render_line();
+  void blank_image();
 
 public:
   sstv_pd120_sink_impl(const char *filename_png);