[Live-devel] Live555 scalability issue.

[Nuno Mota]

Hi,

a couple of days ago i conducted some scalability tests with the live555
media server. The computer in test was a quad core that handle the job
pretty well and of course a Gigabit port was used. For the last test I used
several openRTSP clients. The video source I used was a transport steam
file. The normal client downloads an average of 10Mbit/s (1,3Mbytes/s). For
the test I created 68 clients all connecting to the same live555 server. The
connection sequence was the following, 25 clients, 24 clients, 12 clients
and 8. For the first 49 clients the connection was stable and normal, having
a total throughput of more than 500Mbit/s. However when connecting the next
12 and 8, the bandwidth was reduced more than 20% for every client i think.
Because testing for one  the average speed was less than 8Mbit/s with a
total Throughput from the server of around 500Mbit/s.

Later when the first 25 clients disconnected and the rest remained, the
connection went up  reaching almost 750Mbit for 5 minutes and just for 44
clients, meaning they were compensating I guess for the stream delay. In the
end all the remaining clients had a video file almost identical to the
original one (missing a few seconds maybe). Why did this happen?
Why couldn't the bandwidth keep up for all the users? I'm guessing ofcourse
this is due to the RTCP protocol. But i can't understand why this is
happening.

Regards,
Nuno Mota
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