[icecast] memory, processor, bandwidth

Kerry Cox kjcox at quasi.ksl.com
Thu May 23 07:43:16 PDT 2002



> > If you want to broadcast to listeners, you'll need:
> > 
> > * 90Mhz or faster server, running one of Windows 95, 98, NT, 2000, ME,
> >   Mac OS X, Sparc Solaris 2.x, FreeBSD 3.x, FreeBSD 4.x, or Linux with
> >   a libc6 kernel.
> 
> I don't know if icecast works under non-unix like systems, however
> it doesn't consume much CPU resource it seems.
> 
> the big resource hog is the encoder, which you may or may not install on
> the same machine than the icecast server.

Interesting. On our 1.8 GHz system with 512 megs of RAM, it is not the
encoder that takes up the resources but the streamer. Of course, we are
using MuSE and that requires an X Window environment.But I find LAME to
work exceptionally well for encoding our raw audio stream into MP3
format. Version 3.91 installs without a hitch on Red Hat 7.3.
I'm still looking to test out ices, but haven't had the time. Installing
and setting up icecast, lame and MuSE took about 5 minutes to get up and
running.
I have a small document I made for the other non-technical people here
(in case Kerry gets hit by a bus) that I would be happy to share. Write
me if you are having problems.
Our stream is located at
        http://www.ksl.com/radio/listen/listen.php
and it works great. We faked the Windows Media stream and simply have
the MP3 and WM streams pointing to our icecast box.
 
> > * 14kB of memory for every listener you want to broadcast to (i.e. 1,000
> >   listeners means you need 14 Megabytes of RAM), plus whatever your
> >   operating system needs for overhead, plus 1.5MB for the server's
> >   base requirements.  Don't set the listener count higher than you need,
> >   it just screws things up.

We find that even with a full OC3, we could only handle about 350
listeners. But, of course that was on an old 333 Celeron with 64 megs of
RAM. The limitation was not the bandwidth but the processor power. Over
350 streams and we would start dropping people. The CPU could not handle
it.
We're encoding at 16 kbps which give great quality sound for AM radio.
Hope that helps.

> I seem to remember having read 32 kB for each icecast client, but maybe 
> I'm wrong
> > 
> > * Enough bandwidth to run the server.  If you want to broadcast to 100
> >   listeners at 24kbps, you'll need about 24kbps*100 = 2,400kbps = 2.4Mbps
> >   of bandwidth.  That's about 2 T1 lines worth of bandwidth.  Trying to
> >   push 100 128kbps listeners down your 768kbps cable modem isn't going
> >   to work :)
> 
> Why would this one be different ?
> 
> hth.
> 
> Jerome Alet - Medicine School of Nice - France
> 
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-- 

/-----------------------------\  /--------------------------\
|       Kerry J. Cox          |__|   kerry.cox at ksl.com      |
|   KSL System Administrator   __     p: 801.575.7771       |
|    http://www.ksl.com/      |  |    f: 801.575.5745       |
\-----------------------------/  \--------------------------/

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