[asterisk-users] DAHDI Question/Choppy Sound

[Tzafrir Cohen]

On Mon, Sep 28, 2009 at 01:38:02AM +0300, Andrei Verovski (aka MacGuru) wrote:
> Hi!
> 
> I have Asterisk 1.6.1 installed on OpenSuSE 11.0 running with choppy sound. 
> One specialist on the forums asked me if I have DAHDI configured, he assumed 
> that this could be cause of choppy sound problem.
> 
> > dahdi_test
> Unable to open dahdi interface: No such file or directory 
> 
> Do I need to configure DAHDI even if I do not have any Zaptel devices?

DAHDI uses DAHDI devices, not Zaptel devices. While both have major
number 196, Zaptel devices reside under /dev/zap and dahdi devices
reside under /dev/dahdi . They use different ioctl numbers. But that's
just a technicality.

As of Asterisk 1.6.1 Asterisk can use alternative timing sources.

$ ls /usr/lib/asterisk/modules/res_timing_*
/usr/lib/asterisk/modules/res_timing_dahdi.so
/usr/lib/asterisk/modules/res_timing_pthread.so

'dahdi' is the traditional DAHDI timing source. 'pthread' is a new one,
not as good as dahdi, but much more portable. Asterisk 1.6.2 also
provides res_timing_timerfd that uses a newer Linux API (included as of
Linux 2.6.27, which is why my my system does not support it: 2.6.26).

Apart from timing, DAHDI is also used for mixing the conferencing in
app_meetme.

> 
> Is there any guide for configuring "dummy" DAHDI for Asterisk 1.6?

1.6.0: yes.

1.6.1: If dahdi_dummy runs well on the system it will perform better
than res_timing_pthread.

1.6.2-trunk: Unless you can use the timerfd interface (a relatively new
Linux distribution: kernel >= 2.6.27), same answer as for 1.6.1 .

1.6.2 also provides an initial rpelacement for app_meetme
(app_conceference)

-- 
               Tzafrir Cohen
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