[Spread-users] Voice communication using Spread

Roman Selin rsln at wp.pl
Mon Feb 12 18:28:52 EST 2007


 I'm developing voice communication system - with full duplex 
and conference support for several users. It will work on local
 LAN, not WAN. 

>From the technical point of view, it will use GSM technologies: 8 
kHz sampling, one channel, 16 bit samples. GSM compression 
will be used: 160 samples (320 bytes) will be compressed to 33
bytes frame at 50Hz rate. 

Architecture is simple - several clients (usually  ~10) and single broker/switch application. I'm considering using Spread for this 
(single daemon), since group communication system should 
help to implement things like conferencing. 

Did anyone do anything like this before ? I'm very interested in 
any opinions about this. Any performance tuning using
parameters in membership.c ?

Conducting performance tests, I 
noticed that under heavy load (sending a lot of messages to 
group)  Spread sometimes just closes connection. I found 
similar discussion in the list archive, but it didn't help
(I read everything from the group). I've also read a lot about
Spread's blocking behaviour - we can use 
select/poll/epoll/kqueue to detect socket readiness, but 
I/O  can block inside SP_receive or SP_multicast.

Does anyone know the reason Spread sometimes closes connection or blocks indefinitely under heavy load ? 
I use 4.0.0 under Linux (SUSE 9.3, 10.2,).

I also found Spines (http://www.spines.org/) and read paper "An Overlay Architecture for High Quality VoIP Streams" (http://www.cnds.jhu.edu/pub/papers/voip_tmm_06.pdf).
Is Spines actively supported and developed ? Mailing 
list does not seem to be very active.
Does it offer significant performance or other advantage over 
Spread ?

Thanks for any help,

W stylu Joanny Brodzik.
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