avoid potential div by zero

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@3670 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/applications/mod_conference/mod_conference.c

@@ -3256,7 +3256,7 @@ static void *SWITCH_THREAD_FUNC input_thread_run(switch_thread_t *thread, void *
 			int16_t *data;
 
 			data = read_frame->data;
-			samples = read_frame->datalen / sizeof(*data);
+			if ((samples = read_frame->datalen / sizeof(*data))) {
 
                 for (i = 0; i < samples; i++) {
                     energy += abs(data[j]);
@@ -3264,6 +3264,7 @@ static void *SWITCH_THREAD_FUNC input_thread_run(switch_thread_t *thread, void *
                 }
 
                 score = energy / samples;
+            }
 
 			if (score > energy_level) {
 				uint32_t diff = score - energy_level;