Changeset 471 for pjproject/trunk/pjsip-apps/src/samples/sndtest.c

Timestamp:

May 22, 2006 10:48:11 AM (18 years ago)

Author:

bennylp

Message:

Change jitter calculation in sound test (sndtest) to show the worst jitter value

File:

• pjproject/trunk/pjsip-apps/src/samples/sndtest.c (modified) (3 diffs)

pjproject/trunk/pjsip-apps/src/samples/sndtest.c

@@ -253 +253 @@
 {
     unsigned i, dur;
+    int ptime;
     unsigned min_jitter, max_jitter, sum_jitter, avg_jitter=0;
 
@@ -298 +299 @@
     }
 
+    /* Calculate frame ptime in usec */
+    ptime = test_data->samples_per_frame * 1000000 /
+            test_data->clock_rate;
+
     /* Calculate jitter */
     min_jitter = 0xFFFFF;
@@ -304 +309 @@
 
     for (i=1; i<strm_data->counter; ++i) {
-        int jitter;
-        jitter = strm_data->delay[i] - strm_data->delay[i-1];
-        if (jitter < 0) jitter = -jitter;
+        int jitter1, jitter2, jitter;
+
+        /* jitter1 is interarrival difference */
+        jitter1 = strm_data->delay[i] - strm_data->delay[i-1];
+        if (jitter1 < 0) jitter1 = -jitter1;
         
+        /* jitter2 is difference between actual and scheduled arrival.
+         * This is intended to capture situation when frames are coming
+         * instantaneously, which will calculate as zero jitter with
+         * jitter1 calculation.
+         */
+        jitter2 = ptime - strm_data->delay[i];
+        if (jitter2 < 0) jitter2 = -jitter2;
+
+        /* Set jitter as the maximum of the two jitter calculations. 
+         * This is intended to show the worst result.
+         */
+        jitter = (jitter1>jitter2) ? jitter1 : jitter2;
+
+        /* Calculate min, max, avg jitter */
         if (jitter < (int)min_jitter) min_jitter = jitter;
         if (jitter > (int)max_jitter) max_jitter = jitter;