Don't count empty buffers when computing the frame rate.
diff --git a/cmds/stagefright/stagefright.cpp b/cmds/stagefright/stagefright.cpp
index 76ec54b..376f3d9 100644
--- a/cmds/stagefright/stagefright.cpp
+++ b/cmds/stagefright/stagefright.cpp
@@ -173,7 +173,7 @@
                 break;
             }
 
-            if ((n++ % 16) == 0) {
+            if (buffer->range_length() > 0 && (n++ % 16) == 0) {
                 printf(".");
                 fflush(stdout);
             }