[Ant-phone-devel] latency

[Matthias Thomae]

Hello Roland and list,

I'm interested in using my old PII-233 notebook (with debian/unstable) 
as a phone, possibly as a 'gateway' for a bluetooth headset. I had the 
impression that ant-phone would just be the right application, and 
installed it yesterday.

At first, I couldn't get the debian package working, getting a 
segmentation fault just after reading /var/lib/isdn/calls. Moving that 
file away helped. By the way, I also noticed that ant-phone was looking 
for some isdn.conf file in /home/ernie.

As I don't have a bluetooth headset yet, I tried a wired one on the 
built-in soundcard (ESS1868, I think that's a ISA chip), via the OSS 
emulation af ALSA. The notebook is wirelessly connected through an USB 
bluetooth dongle to an AVM BlueFritz AP-X, with bluez, the capi profile 
and the i4l compatibility module (capidrv), see 
http://www.holtmann.org/linux/bluetooth/isdn.html

This setup technically worked, however there is a latency of half a 
second or a second or so, which makes the whole thing impractible (at 
least for me).

Before I start doing more tests, I'd like to know if there are ideas 
around to the cause (and solutions) of these delays. I could think of:

- the relatively slow cpu
- the bluetooth connection, however pings are in the range of 50 ms
- the sound driver
- the soundcard itself

Regards.
Matthias