[vlc-devel] [streaming] VLC Scalability

Marshall Eubanks tme at multicasttech.com
Thu Feb 5 11:47:18 CET 2009

On Feb 5, 2009, at 5:03 AM, Philip Frey1 wrote:

> Hello,
> we are running an experiment to evaluate the scalability of the VLC  
> in RTP mode.
> For some reason we find that the server does not scale beyond 330  
> clients no
> matter what bitrate our movie is (we are streaming Quicktime content).
> When streaming Full HD content (~9Mbps), the number of clients is  
> limited by the
> CPU power of the server. When using Standard Definition content  
> (~1Mbps and ~3Mbps),
> the CPU load increases up to about 330 connected client and then  
> dropps suddenly
> to almost 0 and the clients no longer receive any data.
> Do you have an explanation for this behavior? Is there a hard limit  
> on the number of
> clients that can connect to the VLC server using RTP?

It would be useful to specify the operating system and hardware that
these tests are being conducted on, and also the disk I/O speed. I  
find that
disk I/O speeds are the biggest limit in practice to scaling on (qtss)  

Also, are you sending 1 copy of the same stream to many clients, or  
different copies
of different streams to many clients ? This has a big effect on the  
disk I/O issue.


> We were running the same experiments also on the Darwin Streaming  
> Server and
> found that DSS can do up to 400 clients (and even more) for small  
> bitrates.
> With regard to HD content, the DSS is also limited by the CPU on the  
> server.
> Many thanks for your advice,
>  Philip
> -- 
>   Philip Frey
>   IBM Zurich Research Laboratory
>   Saumerstrasse 4                                   |  Phone: +41 44  
> 724 8613
>   CH-8803 Rueschlikon/Switzerland  |  Email: phf at zurich.ibm.com_______________________________________________
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