Audio Problem: Audio Drop-outs or Stutters

Symptoms

The audio is sounding like it's skipping some frames.

Sample WAV File

See the attachment on the bottom of this page. You can hear the stutters at 2.5 second, 3.8 second, 8.8 second.

(audio file courtesy of Chen Huan <chenhuan at sict.ac.cn> who managed to convince his girlfriend to record the audio for testing :) ).

Checklists

Here are the checklists related to stutters problem:

1. Check whether the symptom is observable when looping the microphone to the speaker locally.
2. Check that there is no dangling call in the PBX. A dangling call is call that is left active in the PBX because previous (pjsua) application has crashed.
3. Check for network impairments of incoming RTP packets
4. Check that CPU Utilization is not Too High
5. For Windows Mobile/WinCE, it may be necessary to set PJMEDIA_SOUND_BUFFER_COUNT to 32 in your pj/config_site.h. The default value is 16, which is fine for desktop applications. But be aware that enlarging this buffer may increase the audio delay (thanks Chen Huan for reporting this).
6. Check for audio underflows/overflows