add hacky snr peak masking

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/audiowmark.cc

@@ -419,13 +419,32 @@ test_snr (const string& orig_file, const string& wm_file)
   assert (orig_data.n_values() == wm_data.n_values());
   assert (orig_data.n_channels() == orig_data.n_channels());
 
-  const auto& orig_signal = orig_data.samples();
+  auto orig_signal = orig_data.samples();
   const auto& wm_signal = wm_data.samples();
 
+  for (int m = 0; m < orig_signal.size(); m++)
+    {
+      if (fabs (orig_signal[m]) > 0.9)
+        {
+          for (int k = -1000; k < 1000; k++)
+            {
+              if (m + k >= 0 && m + k < int (orig_signal.size()))
+                orig_signal[m + k] = 0;
+            }
+        }
+    }
+
+#if 0
+  WavData out_wav_data (orig_signal, orig_data.n_channels(), orig_data.sample_rate(), orig_data.bit_depth());
+  out_wav_data.save ("/tmp/foo.wav");
+#endif
+
   double snr_delta_power = 0;
   double snr_signal_power = 0;
 
   for (size_t i = 0; i < orig_signal.size(); i++)
+    {
+      if (orig_signal[i] != 0)
         {
           const double orig  = orig_signal[i];                // original sample
           const double delta = orig_signal[i] - wm_signal[i]; // watermark
@@ -433,6 +452,7 @@ test_snr (const string& orig_file, const string& wm_file)
           snr_delta_power += delta * delta;
           snr_signal_power += orig * orig;
         }
+    }
   printf ("%f\n", 10 * log10 (snr_signal_power / snr_delta_power));
   return 0;
 }