Improve DTMF handling in ast_read() even more in response to a discussion on

the asterisk-dev mailing list.  I changed the enforced minimum length of a
digit from 100ms to 80ms.  Furthermore, I made it now enforce a gap of 45ms in
between digits.  These values are not configurable in a configuration file
right now, but they can be easily changed near the top of main/channel.c.


git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.4@61781 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 45 insertions, 18 deletions

diff --git a/main/channel.c b/main/channel.c
index f0215851b..095471598 100644
--- a/main/channel.c
+++ b/main/channel.c
@@ -104,9 +104,17 @@ unsigned long global_fin, global_fout;
 AST_THREADSTORAGE(state2str_threadbuf, state2str_threadbuf_init);
 #define STATE2STR_BUFSIZE   32
 
-/*! 100ms */
+/*! Default amount of time to use when emulating a digit as a begin and end 
+ *  100ms */
 #define AST_DEFAULT_EMULATE_DTMF_DURATION 100
 
+/*! Minimum allowed digit length - 80ms */
+#define AST_MIN_DTMF_DURATION 80
+
+/*! Minimum amount of time between the end of the last digit and the beginning 
+ *  of a new one - 45ms */
+#define AST_MIN_DTMF_GAP 45
+
 struct chanlist {
 	const struct ast_channel_tech *tech;
 	AST_LIST_ENTRY(chanlist) list;
@@ -2113,7 +2121,8 @@ static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio)
 	prestate = chan->_state;
 
 	if (!ast_test_flag(chan, AST_FLAG_DEFER_DTMF | AST_FLAG_EMULATE_DTMF | AST_FLAG_IN_DTMF) && 
-	    !ast_strlen_zero(chan->dtmfq)) {
+	    !ast_strlen_zero(chan->dtmfq) && 
+		(ast_tvzero(chan->dtmf_tv) || ast_tvdiff_ms(ast_tvnow(), chan->dtmf_tv) > AST_MIN_DTMF_GAP) ) {
 		/* We have DTMF that has been deferred.  Return it now */
 		chan->dtmff.subclass = chan->dtmfq[0];
 		/* Drop first digit from the buffer */
@@ -2126,8 +2135,8 @@ static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio)
 			ast_set_flag(chan, AST_FLAG_EMULATE_DTMF);
 			chan->emulate_dtmf_digit = f->subclass;
 			chan->emulate_dtmf_duration = AST_DEFAULT_EMULATE_DTMF_DURATION;
-			chan->dtmf_begin_tv = ast_tvnow();
 		}
+		chan->dtmf_tv = ast_tvnow();
 		goto done;
 	}
 	
@@ -2264,34 +2273,50 @@ static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio)
 				ast_frfree(f);
 				f = &ast_null_frame;
 			} else if (!ast_test_flag(chan, AST_FLAG_IN_DTMF | AST_FLAG_END_DTMF_ONLY)) {
-				f->frametype = AST_FRAME_DTMF_BEGIN;
-				ast_set_flag(chan, AST_FLAG_EMULATE_DTMF);
-				chan->emulate_dtmf_digit = f->subclass;
-				chan->dtmf_begin_tv = ast_tvnow();
-				if (f->len && f->len > AST_DEFAULT_EMULATE_DTMF_DURATION)
-					chan->emulate_dtmf_duration = f->len;
-				else
-					chan->emulate_dtmf_duration = AST_DEFAULT_EMULATE_DTMF_DURATION;
+				if (!ast_tvzero(chan->dtmf_tv) && 
+				    ast_tvdiff_ms(ast_tvnow(), chan->dtmf_tv) < AST_MIN_DTMF_GAP) {
+					/* If it hasn't been long enough, defer this digit */
+					if (strlen(chan->dtmfq) < sizeof(chan->dtmfq) - 2)
+						chan->dtmfq[strlen(chan->dtmfq)] = f->subclass;
+					else
+						ast_log(LOG_WARNING, "Dropping deferred DTMF digits on %s\n", chan->name);
+					ast_frfree(f);
+					f = &ast_null_frame;
+				} else {
+					/* There was no begin, turn this into a begin and send the end later */
+					f->frametype = AST_FRAME_DTMF_BEGIN;
+					ast_set_flag(chan, AST_FLAG_EMULATE_DTMF);
+					chan->emulate_dtmf_digit = f->subclass;
+					chan->dtmf_tv = ast_tvnow();
+					if (f->len && f->len > AST_MIN_DTMF_DURATION)
+						chan->emulate_dtmf_duration = f->len;
+					else
+						chan->emulate_dtmf_duration = AST_MIN_DTMF_DURATION;
+				}
 			} else {
+				struct timeval now = ast_tvnow();
 				ast_clear_flag(chan, AST_FLAG_IN_DTMF);
 				if (!f->len)
-					f->len = ast_tvdiff_ms(ast_tvnow(), chan->dtmf_begin_tv);
-				if (f->len < AST_DEFAULT_EMULATE_DTMF_DURATION) {
+					f->len = ast_tvdiff_ms(now, chan->dtmf_tv);
+				if (f->len < AST_MIN_DTMF_DURATION) {
 					ast_set_flag(chan, AST_FLAG_EMULATE_DTMF);
 					chan->emulate_dtmf_digit = f->subclass;
-					chan->emulate_dtmf_duration = AST_DEFAULT_EMULATE_DTMF_DURATION - f->len;
+					chan->emulate_dtmf_duration = AST_MIN_DTMF_DURATION - f->len;
 					f = &ast_null_frame;
-				}
+				} else
+					chan->dtmf_tv = now;
 			}
 			break;
 		case AST_FRAME_DTMF_BEGIN:
 			ast_log(LOG_DTMF, "DTMF begin '%c' received on %s\n", f->subclass, chan->name);
-			if (ast_test_flag(chan, AST_FLAG_DEFER_DTMF | AST_FLAG_END_DTMF_ONLY)) {
+			if ( ast_test_flag(chan, AST_FLAG_DEFER_DTMF | AST_FLAG_END_DTMF_ONLY) || 
+			    (!ast_tvzero(chan->dtmf_tv) && 
+			      ast_tvdiff_ms(ast_tvnow(), chan->dtmf_tv) < AST_MIN_DTMF_GAP) ) {
 				ast_frfree(f);
 				f = &ast_null_frame;
 			} else {
 				ast_set_flag(chan, AST_FLAG_IN_DTMF);
-				chan->dtmf_begin_tv = ast_tvnow();
+				chan->dtmf_tv = ast_tvnow();
 			}
 			break;
 		case AST_FRAME_VOICE:
@@ -2309,10 +2334,12 @@ static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio)
 				f = &ast_null_frame;
 			} else if (ast_test_flag(chan, AST_FLAG_EMULATE_DTMF)) {
 				if ((f->samples / 8) >= chan->emulate_dtmf_duration) { /* XXX 8kHz */
+					struct timeval now = ast_tvnow();
 					chan->emulate_dtmf_duration = 0;
 					f->frametype = AST_FRAME_DTMF_END;
 					f->subclass = chan->emulate_dtmf_digit;
-					f->len = ast_tvdiff_ms(ast_tvnow(), chan->dtmf_begin_tv);
+					f->len = ast_tvdiff_ms(now, chan->dtmf_tv);
+					chan->dtmf_tv = now;
 				} else {
 					chan->emulate_dtmf_duration -= f->samples / 8; /* XXX 8kHz */
 					ast_frfree(f);