Changed default sound back-end on Win32 to own DirectSound

git-svn-id: https://svn.pjsip.org/repos/pjproject/trunk@445 74dad513-b988-da41-8d7b-12977e46ad98
diff --git a/pjsip-apps/src/samples/sndinfo.c b/pjsip-apps/src/samples/sndinfo.c
index 3a18416..5ddc67a 100644
--- a/pjsip-apps/src/samples/sndinfo.c
+++ b/pjsip-apps/src/samples/sndinfo.c
@@ -127,7 +127,7 @@
 
     ++rec_counter;
 
-    if (timestamp - last_rec_timestamp >= clock_rate) {
+    if (timestamp - last_rec_timestamp >= clock_rate && last_play_timestamp) {
 	int diff;
 	diff = last_play_timestamp - timestamp;
 	printf("Play timestamp=%u, capture timestamp=%u, diff=%d\n",