[Freeswitch-users] Conference timer synchronization with T1 FreeTDM - how?

[Bob Hartwig]

Hi Moises,

On Tue, Sep 24, 2013 at 9:55 PM, Moises Silva <moises.silva at gmail.com>wrote:

>
> The input thread IO timing seems to be completely based on the endpoint
> read clock (in FreeTDM case, using hardware timer). The output thread on
> the other hand uses the soft-timer to time the calls to
> switch_core_session_write() (and then internally the write will be timed by
> the hardware timer, again).
>

Sorry if this is a dumb question, but is there any way to hack things to
make all of FreeSWITCH sync up with the FreeTDM clock source?  I.e. the
"soft" timer would be synchronized to the FreeTDM clock source?



>
>
>> I'm seeing some weirdness with my FreeTDM / Dahdi system, where only
>> FreeTDM channels are hearing distortion on conference, and I'm almost
>> certain that this is the culprit, but I have no idea how to proceed to fix
>> it.  I'm pretty new to FreeTDM, so I'm hoping that I'm missing something
>> simple.  Any thoughts?
>>
>
> What kind of distortion exactly?
>
>
Here is how I described it in an earlier email:  "I would classify the
distortion as a "crackle", but it is very regularly periodic.  Repeating
ticks at (roughly) 10-20 Hz repeat rate, I would say.  I can only hear them
when audio is present, i.e. the audio seems to be modulated with the ticks.
 And that conference audio can be the MOH guitar recording."  It is only on
conference, and only for TDM channels.  WAV file playback does not have the
problem (but I assume that playing a WAV on conference would, since MOH
does).




> You may want to use the "ftdm trace" command to record the audio
> read/written to the TDM endpoint and see if the audio is clean when written
> to the tdm endopoint.
>
>
OK, I'll try that.



>
> What sampling rate is your conference? what packetization size? (20ms,
> 30ms, 40ms??) what kind of hardware are you using?
>
>
8000, 20 mS (and I verified that everything is 20), and a quad Rhino board
using Dahdi.

    Thanks,
    Bob
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