[asterisk-commits] russell: branch 1.4 r80820 - /branches/1.4/main/dsp.c

[SVN commits to the Asterisk project]

Author: russell
Date: Fri Aug 24 15:24:05 2007
New Revision: 80820

URL: http://svn.digium.com/view/asterisk?view=rev&rev=80820
Log:
Improve the debouncing logic in the DTMF detector to fix some reliability
issues.  Previously, this code used a shift register of hits and non-hits.
However, if the start of the digit isn't clean, it is possible for the
leading edge detector to miss the digit.  These changes replace the flawed
shift register logic and also does the debouncing on the trailing edge as well.
(closes issue #10535, many thanks to softins for the patch)

Modified:
    branches/1.4/main/dsp.c

Modified: branches/1.4/main/dsp.c
URL: http://svn.digium.com/view/asterisk/branches/1.4/main/dsp.c?view=diff&rev=80820&r1=80819&r2=80820
==============================================================================
--- branches/1.4/main/dsp.c (original)
+++ branches/1.4/main/dsp.c Fri Aug 24 15:24:05 2007
@@ -217,7 +217,7 @@
 	int hit3;
 	int hit4;
 #else
-	int hits[3];
+	int lasthit;
 #endif	
 	int mhit;
 	float energy;
@@ -371,7 +371,7 @@
 	s->hit4 = 
 	s->hit2 = 0;
 #else
-	s->hits[0] = s->hits[1] = s->hits[2] = 0;
+	s->lasthit = 0;
 #endif
 	for (i = 0;  i < 4;  i++) {
 		goertzel_init (&s->row_out[i], dtmf_row[i], 102);
@@ -595,6 +595,7 @@
 						amp[i] = 0;
 					*writeback = 1;
 				}
+#ifdef OLD_DSP_ROUTINES
 				/* Look for two successive similar results */
 				/* The logic in the next test is:
 				   We need two successive identical clean detects, with
@@ -602,7 +603,6 @@
 				   back to back differing digits. More importantly, it
 				   can work with nasty phones that give a very wobbly start
 				   to a digit */
-#ifdef OLD_DSP_ROUTINES
 				if (hit == s->hit3  &&  s->hit3 != s->hit2) {
 					s->mhit = hit;
 					s->digit_hits[(best_row << 2) + best_col]++;
@@ -614,21 +614,33 @@
 						s->lost_digits++;
 					}
 				}
-#else				
-				if (hit == s->hits[2]  &&  hit != s->hits[1]  &&  hit != s->hits[0]) {
-					s->mhit = hit;
-					s->digit_hits[(best_row << 2) + best_col]++;
-					s->detected_digits++;
-					if (s->current_digits < MAX_DTMF_DIGITS) {
-						s->digits[s->current_digits++] = hit;
-						s->digits[s->current_digits] = '\0';
-					} else {
-						s->lost_digits++;
-					}
+#endif
+			}
+		} 
+
+#ifndef OLD_DSP_ROUTINES
+		/* Look for two successive similar results */
+		/* The logic in the next test is:
+		   We need two successive identical clean detects, with
+		   something different preceeding it. This can work with
+		   back to back differing digits. More importantly, it
+		   can work with nasty phones that give a very wobbly start
+		   to a digit */
+		if (hit == s->lasthit  &&  hit != s->mhit) {
+			if (hit) {
+				s->digit_hits[(best_row << 2) + best_col]++;
+				s->detected_digits++;
+				if (s->current_digits < MAX_DTMF_DIGITS) {
+					s->digits[s->current_digits++] = hit;
+					s->digits[s->current_digits] = '\0';
+				} else {
+					s->lost_digits++;
 				}
-#endif
-			}
-		} 
+			}
+			s->mhit = hit;
+		}
+#endif
+
 #ifdef FAX_DETECT
 		if (!hit && (fax_energy >= FAX_THRESHOLD) && 
 			(fax_energy >= DTMF_TO_TOTAL_ENERGY*s->energy) &&
@@ -659,9 +671,7 @@
 		s->hit2 = s->hit3;
 		s->hit3 = hit;
 #else
-		s->hits[0] = s->hits[1];
-		s->hits[1] = s->hits[2];
-		s->hits[2] = hit;
+		s->lasthit = hit;
 #endif		
 		/* Reinitialise the detector for the next block */
 		for (i = 0;  i < 4;  i++) {
@@ -681,11 +691,15 @@
 		s->energy = 0.0;
 		s->current_sample = 0;
 	}
+#ifdef OLD_DSP_ROUTINES
 	if ((!s->mhit) || (s->mhit != hit)) {
 		s->mhit = 0;
 		return(0);
 	}
 	return (hit);
+#else
+	return (s->mhit);	/* return the debounced hit */
+#endif
 }
 
 /* MF goertzel size */
@@ -1709,7 +1723,7 @@
 #endif
 		dsp->td.dtmf.hit1 = dsp->td.dtmf.hit2 = dsp->td.dtmf.hit3 = dsp->td.dtmf.hit4 = dsp->td.dtmf.mhit = 0;
 #else
-		dsp->td.dtmf.hits[2] = dsp->td.dtmf.hits[1] = dsp->td.dtmf.hits[0] =  dsp->td.dtmf.mhit = 0;
+		dsp->td.dtmf.lasthit = dsp->td.dtmf.mhit = 0;
 #endif		
 		dsp->td.dtmf.energy = 0.0;
 		dsp->td.dtmf.current_sample = 0;