[pjsip] Poor Voice Quality on Windows Mobile 6 (with Codecs other than G711)

Benny Prijono bennylp at pjsip.org
Thu Apr 24 08:38:36 EDT 2008

On Thu, Apr 24, 2008 at 10:43 AM, girish_kumar <girish_kumar at infosys.com> wrote:
> Hi,
> We have built PJSIP for wince platform and deployed it on to Windows Mobile
> 6 based device without exploring any media optimizations.
> The Voice quality is fine with both variants of G.711 codec and CPU
> utilization is observed at around 50%. However, if try to use iLBC or Speex
> (Narrow-band) codecs, the voice quality drops drastically to an
> unrecognizable level and CPU utilization shoots into 90-100% range.

Hi Girish,

the CPU usage for G711 looks too much, it shouldn't be that high for
G711 IMO. If you're using relatively latest SVN version (the one with
WSOLA in it), please update again to the very latest SVN version. In
current SVN, WSOLA is disabled on both WinCE and Symbian (via
config_site_sample.h) since it seems that it's a bit too much for
these devices.

Having said that, I've never heard people successfully use Speex on
PDA/mobile devices. IMO Speex is just too demanding for these devices.
And probably iLBC is too. But GSM should work, and if you can afford
the bandwidth, G.722.

> Has anyone used PJSIP on Windows Mobile 6 and can verify if these
> observations on Voice quality are justified? Please suggest some
> optimizations to improve the quality of voice.
> Also, the Echo Cancellation is resulting in Jittery Voice (for G.711 codec)
> while Echo Suppression works fine. Any suggestions.

The EC is probably too much for mobile devices too, hence it's
disabled by default.


> Thanks
> Girish
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