Changeset 1839 for pjproject/trunk

Timestamp:

Mar 3, 2008 1:25:17 PM (17 years ago)

Author:

bennylp

Message:

Ticket #499: NULL frame transmission in conference bridge is not clocked at the right interval

File:

• pjproject/trunk/pjmedia/src/pjmedia/conference.c (modified) (4 diffs)

pjproject/trunk/pjmedia/src/pjmedia/conference.c

@@ -180 +180 @@
     unsigned             tx_buf_count;  /**< # of samples in the buffer.    */
 
+    /* When the port is not receiving signal from any other ports (e.g. when
+     * no other ports is transmitting to this port), the bridge periodically
+     * transmit NULL frame to the port to keep the port "alive" (for example,
+     * a stream port needs this heart-beat to periodically transmit silence
+     * frame to keep NAT binding alive).
+     *
+     * This NULL frame should be sent to the port at the port's ptime rate.
+     * So if the port's ptime is greater than the bridge's ptime, the bridge
+     * needs to delay the NULL frame until it's the right time to do so.
+     *
+     * This variable keeps track of how many pending NULL samples are being
+     * "held" for this port. Once this value reaches samples_per_frame
+     * value of the port, a NULL frame is sent. The samples value on this
+     * variable is clocked at the port's clock rate.
+     */
+    unsigned             tx_heart_beat;
+
     /* Delay buffer is a special buffer for sound device port (port 0, master
      * port) and other passive ports (sound device port is also passive port).
@@ -1389 +1406 @@
         pjmedia_frame frame;
 
-        /* Adjust the timestamp */
+        /* Clear left-over samples in tx_buffer, if any, so that it won't
+         * be transmitted next time we have audio signal.
+         */
+        cport->tx_buf_count = 0;
+
+        /* Add sample counts to heart-beat samples */
+        cport->tx_heart_beat += conf->samples_per_frame * cport->clock_rate /
+                                conf->clock_rate;
+
+        /* Set frame timestamp */
         frame.timestamp.u64 = timestamp->u64 * cport->clock_rate /
                                 conf->clock_rate;
@@ -1396 +1422 @@
         frame.size = 0;
 
+        /* Transmit heart-beat frames (may transmit more than one NULL frame
+         * if port's ptime is less than bridge's ptime.
+         */
         if (cport->port && cport->port->put_frame) {
-            pjmedia_port_put_frame(cport->port, &frame);
+            while (cport->tx_heart_beat >= cport->samples_per_frame) {
+
+                pjmedia_port_put_frame(cport->port, &frame);
+
+                cport->tx_heart_beat -= cport->samples_per_frame;
+                frame.timestamp.u64 += cport->samples_per_frame;
+            }
         }
 
@@ -1409 +1444 @@
         return PJ_SUCCESS;
     }
+
+    /* Reset heart-beat sample count */
+    cport->tx_heart_beat = 0;
 
     buf = (pj_int16_t*) cport->mix_buf;