Add flags to chanspy audiohook so that audio stays in sync.

There are two flags being added to the chanspy audiohook here. One
is the pre-existing AST_AUDIOHOOK_TRIGGER_SYNC flag. With this set,
we ensure that the read and write slinfactories on the audiohook do
not skew beyond a certain tolerance.

In addition, there is a new audiohook flag added here,
AST_AUDIOHOOK_SMALL_QUEUE. With this flag set, we do not allow for
a slinfactory to build up a substantial amount of audio before 
flushing it. For this particular issue, this means that the person 
spying on the call will hear the conversations in real time with very 
little delay in the audio.

(closes issue #13745)
Reported by: geoffs
Patches:
      13745.patch uploaded by mmichelson (license 60)
Tested by: snblitz



git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.4@197537 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 11 insertions, 1 deletions

diff --git a/main/audiohook.c b/main/audiohook.c
index d055a73f1..ec6f0f316 100644
--- a/main/audiohook.c
+++ b/main/audiohook.c
@@ -130,6 +130,7 @@ int ast_audiohook_write_frame(struct ast_audiohook *audiohook, enum ast_audiohoo
 	struct ast_slinfactory *factory = (direction == AST_AUDIOHOOK_DIRECTION_READ ? &audiohook->read_factory : &audiohook->write_factory);
 	struct ast_slinfactory *other_factory = (direction == AST_AUDIOHOOK_DIRECTION_READ ? &audiohook->write_factory : &audiohook->read_factory);
 	struct timeval *time = (direction == AST_AUDIOHOOK_DIRECTION_READ ? &audiohook->read_time : &audiohook->write_time), previous_time = *time;
+	int our_factory_samples;
 	int our_factory_ms;
 	int other_factory_samples;
 	int other_factory_ms;
@@ -137,7 +138,8 @@ int ast_audiohook_write_frame(struct ast_audiohook *audiohook, enum ast_audiohoo
 	/* Update last feeding time to be current */
 	*time = ast_tvnow();
 
-	our_factory_ms = ast_tvdiff_ms(*time, previous_time) + (ast_slinfactory_available(factory) / 8);
+	our_factory_samples = ast_slinfactory_available(factory);
+	our_factory_ms = ast_tvdiff_ms(*time, previous_time) + (our_factory_samples / 8);
 	other_factory_samples = ast_slinfactory_available(other_factory);
 	other_factory_ms = other_factory_samples / 8;
 
@@ -149,6 +151,14 @@ int ast_audiohook_write_frame(struct ast_audiohook *audiohook, enum ast_audiohoo
 		ast_slinfactory_flush(other_factory);
 	}
 
+	if (ast_test_flag(audiohook, AST_AUDIOHOOK_SMALL_QUEUE) && (our_factory_samples > 640 || other_factory_samples > 640)) {
+		if (option_debug) {
+			ast_log(LOG_DEBUG, "Audiohook %p has stale audio in its factories. Flushing them both\n", audiohook);
+		}
+		ast_slinfactory_flush(factory);
+		ast_slinfactory_flush(other_factory);
+	}
+
 	/* Write frame out to respective factory */
 	ast_slinfactory_feed(factory, frame);