[Linphone-users] oRTP issue: every inbound packet 20 ms delayed?

[Tobias Engel]

Hi,

I don't know if this is the right list, but I didn't find a dedicated
oRTP mailing list, so I am trying my luck here.

I wrote a small application that uses oRTP with blocking/scheduling to
send and receive audio frames. I soon realized that for all packets I
receive through rtp_session_recv_with_ts, there was a 20ms delay between
when they were received on the socket and when they were returned to my
application. I thought I must be doing something wrong, but the included
test application "rtprecv" shows the exact same behaviour.

Below is a small patch against the current git HEAD that will output a 
timestamp everytime a packet is received on the socket (after recvmsg is 
called), and when it is returned to the application.

I started rtpsend/rtprecv with the following command lines:
$ ./rtprecv /dev/null 12345
and
$ ./rtpsend /dev/zero 127.0.0.1 12345

The output from rtprecv looks like this:
...
14:59:32.100639 rtp_session_recv_with_ts called
14:59:32.100664 received 172 byte message from socket
14:59:32.120794 returning 160 bytes payload
14:59:32.120844 rtp_session_recv_with_ts called
14:59:32.120869 received 172 byte message from socket
14:59:32.140008 returning 160 bytes payload
...

As you can see, there is a 20ms delay between receiving the packet and
returning it (right from the very first recevied packet).

Is there anybody who can help me with this? Maybe I am misinterpreting
something? But shouldn't the wait occur *before* the packet is received?

Many thanks in advance,
-Tobias



diff --git a/src/rtpsession.c b/src/rtpsession.c
index 79195ba..bb057f2 100644
--- a/src/rtpsession.c
+++ b/src/rtpsession.c
@@ -1247,6 +1247,12 @@ int rtp_session_recv_with_ts (RtpSession * session,
uint8_t * buffer,
        mblk_t *mp=NULL;
        int plen,blen=0;
        *have_more=0;
+
+       struct timeval tv;
+       gettimeofday(&tv, 0);
+       struct tm tmlocal= *localtime(&tv.tv_sec);
+       fprintf(stderr, "%02d:%02d:%02d.%06d rtp_session_recv_with_ts called\n",
tmlocal.tm_hour, tmlocal.tm_min, tmlocal.tm_sec, (int)tv.tv_usec);
+
        while(1){
                if (session->pending){
                        mp=session->pending;
@@ -1276,6 +1282,11 @@ int rtp_session_recv_with_ts (RtpSession * session,
uint8_t * buffer,
                        }
                }else break;
        }
+
+       gettimeofday(&tv, 0);
+       tmlocal= *localtime(&tv.tv_sec);
+       fprintf(stderr, "%02d:%02d:%02d.%06d returning %d bytes payload\n",
tmlocal.tm_hour, tmlocal.tm_min, tmlocal.tm_sec, (int)tv.tv_usec, blen);
+
        return blen;
 }
 /**
diff --git a/src/rtpsession_inet.c b/src/rtpsession_inet.c
index 1dffe5e..0649b9a 100644
--- a/src/rtpsession_inet.c
+++ b/src/rtpsession_inet.c
@@ -1149,6 +1149,14 @@ int rtp_session_rtp_recv_abstract(ortp_socket_t
socket, mblk_t *msg, int flags,
        if(fromlen != NULL)
                *fromlen = msghdr.msg_namelen;
        if(ret >= 0) {
+               
+               if(ret > 0) {
+                       struct timeval tv;
+                       gettimeofday(&tv, 0);
+                       struct tm tmlocal= *localtime(&tv.tv_sec);
+                       fprintf(stderr, "%02d:%02d:%02d.%06d received %d byte 
message from
socket\n", tmlocal.tm_hour, tmlocal.tm_min, tmlocal.tm_sec, (int)tv.tv_usec,
ret);
+               }
+
 #else
        char control[512];
        WSAMSG msghdr;