Sound delay in i4b

Dirk Thannhäuser dt at
Mon May 15 10:20:45 UTC 2006

On May 15, 2006, at 9:38 AM, Hans Petter Selasky wrote:

> Hi,
> On Sunday 14 May 2006 22:57, Dirk Thannhäuser wrote:
>> On May 14, 2006, at 3:18 PM, Hans Petter Selasky wrote:
>>> Do you have SVN installed?
>> yes i have. I checked out the version which included both, the i4b
>> and the chan_capi. Is ist possible that my version was to old?
>> I just did a new checkout.
>> Subversion says "Checked out revision 264."
> That should be the latest version. It was fixed in "Revision 257",  
> which was
> after that I released Version 1.6.0 in April.

Hmm. i compiled the latest release (i4b and chan_capi) yesterday and  
tested it with the echo test application. The delay is the same as  
When I call the server internal (My Phone -> ISDNCard(NT) -> Asterisk  
(1.2.4) (isdnd not running. cards set to TE/NT mode via "isdnconfig"  
command . The delay in the echo test application remains unchanged at  
about 250ms to half a second. (not measured, it's just my feeling,  
but i know the difference to the zaptel FreeBSD driver). My machine  
is a Siemens Scenic L (1.6Ghz/512MB RAM). That schould be enough  
power to get low latency.
How easy would it be to play around with changing latencey. Should i  
take a look to the chan_capi sources to get latency changed?

>> Are there any "cheap" HFC-4S cards out there for testing?
> There exist some developer kits, but they are not so easy to get a  
> hand on.
> The only place I know that sales HFC-4S are:

A developer Kit would be the card of my choice.
Does Bero sell them or shoud i contact colognechip?
> And maybe "".
>> I think that this also means that i am not able to run one card
>> (HFC-1S) in slave mode, getting the clock from the other to keep them
>> in sync without soldering.
> Yes.
>> For Voice over IP a huger delay might be ok. thats also my opinion.
>> but what about Faxing over ISDN. Here I think latency is an important
>> issue. (didn't test the CAPI Fax receiption, yet)
> Faxing works, but really you need to use line interconnect to get  
> faxing
> working reliably. Or you can receive the fax in asterisk. That also  
> works.

Does it also work with about 250ms delay? (it exists on both sides  
from my NT-Card to asterisk and also from the TE-Card to asterisk
may be that i did something wrong compiling the sources although i  
cleaned the BSD sourcetree applied the patches again an then started  
compiling the get a "fresh" state an no confusion with the older  
release which was installed before.

> --HPS

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