[Asterisk-bsd] Sound quality with TDM11B

[Staffan Ulfberg]

Hello,

First, I'd just like to say I finally got my TDM11B card probed and
working.  I really do not know what caused it not being detected, but
I installed FreeBSD 5.3 last weekend, and now everything is working.

I'm running the latest wcfxs kernel modules from svn (revision 1034)
-- I couldn't get the ones in the port to detect when the fxo module
was ringing.

I do still have a problem, however: The sound quality from the fxs
module is suffers from intermittent break-ups/stuttering.  It does not
seem to matter whether I have a phone conversation going, or not: just
listening to the dial tone produces the same problem.  Sound quality
is often perfect for a minute or two, and then has period of
clicking/stuttering of maybe 15 seconds.  These times appear random in
practice.

I've read about possible problems with shared interrupts, and have
made sure the TDM11B card is the only peripheral on irq 5.  (It did
share irq 10 with the network adapter, and I had really high hopes the
problem would be fixed when I had moved the cards around and rebooted
with the card on its own interrupt...)

The machine is a 1400 MHz Athlon.  It does run some other services,
but no X, which I've seen people taking about as a potential problem.

Do I understand correctly that the driver code needs to supply eight
samples every interrupt to the card?  Is there no buffer whatsoever
(more than 8 bytes) in the card?  Does the driver detect if this
buffer underruns?  (I tried turning on the driver debug prints, but
there's not much of help coming out.)

Staffan