Much better hysteresis code.
authorSteinar H. Gunderson <sgunderson@bigfoot.com>
Sat, 4 May 2013 13:50:31 +0000 (15:50 +0200)
committerSteinar H. Gunderson <sgunderson@bigfoot.com>
Sat, 4 May 2013 13:50:31 +0000 (15:50 +0200)
decode.cpp

index 8e0adaa..e3ec677 100644 (file)
@@ -125,10 +125,31 @@ int main(int argc, char **argv)
        // Find the flanks.
        int last_bit = -1;
        double last_upflank = -1;
-       int last_max_level = 0;
        for (unsigned i = 0; i < pcm.size(); ++i) {
                int bit = (pcm[i] > 0) ? 1 : 0;
-               if (bit == 1 && last_bit == 0 && last_max_level > HYSTERESIS_LIMIT) {
+               if (bit == 1 && last_bit == 0) {
+                       // Check if we ever go up above HYSTERESIS_LIMIT before we dip down again.
+                       bool true_pulse = false;
+                       unsigned j;
+                       int max_level_after = -32768;
+                       for (j = i; j < pcm.size(); ++j) {
+                               max_level_after = std::max<int>(max_level_after, pcm[j]);
+                               if (pcm[j] < 0) break;
+                               if (pcm[j] > HYSTERESIS_LIMIT) {
+                                       true_pulse = true;
+                                       break;
+                               }
+                       }
+
+                       if (!true_pulse) {
+#if 0
+                               fprintf(stderr, "Ignored up-flank at %.6f seconds due to hysteresis (%d < %d).\n",
+                                       double(i) / SAMPLE_RATE, max_level_after, HYSTERESIS_LIMIT);
+#endif
+                               i = j;
+                               continue;
+                       } 
+
                        // up-flank!
                        double t = find_zerocrossing(pcm, i - 1) * (1.0 / SAMPLE_RATE);
                        if (last_upflank > 0) {
@@ -138,9 +159,7 @@ int main(int argc, char **argv)
                                pulses.push_back(p);
                        }
                        last_upflank = t;
-                       last_max_level = 0;
                }
-               last_max_level = std::max(last_max_level, abs(pcm[i]));
                last_bit = bit;
        }