Server bandwidth usage with rtmp streaming of video

A few thoughts;

• What's your client software, this is very important, specific versions on specific OSs - this will define your streaming software.
• What are your stream profiles, do you intend to pre-encode or do you have/expect-to cross-encode on the fly?
• Have you done your maths on average and burst bandwidth requirements for this, is your top end figure taking into account the entire path from disk/memory to CPU, IO, NICs, L2, L3, load-balancers, firewalls, any VPNs you might have/need, external routing, onward transit etc.
• Are you planning on serving non-stream traffic (front page, transactional etc) from the streaming server? if so why as this traffic can easily handle jitter but video can't - consider splitting your front-end into workload types, makes for easier scale-out.
• Consider now how you're going to 'tap' into live content, there's a good chance that you'll need this ability for rights compliance.

As for hardware, well it sounds to me that you need both performance and resilience, you'll struggle to get this at bargain basement prices, stick to one of the mid/big-boys (Dell or better) rather than build-your-own - you're going to be busy enough as it is.

Hope this has been of some use.

We went with FMS because of its built in fuctionality with flash clients, and was still pretty cheap (in context) to license. It also came with some demo apps that almost perfectly suited our needs. In fact if it's <= 5 users then the demo license will be fine.

That said, we didn't look into the Windows Media Server much because we didn't have any developers with experience in it, so I can't provide a fair comparison.

One thing we really liked was the ability in FMS to publish at multiple bit levels, because we were streaming to churches in remote locations they could only handle say 256kbps, whereas those in the city or at home could handle 1500kbps, and FMS let the user switch on the fly without a dropout in stream. It would even automatically switch down a bitrate if the local connection couldn't keep up.