HDX MediaStream is our name for a set of Citrix technologies for delivering video and audio content from virtual desktops and hosted applications. The foundation of HDX MediaStream is the ability to deliver any media format from any media player over any network connection to any device. (Did I use the "any" word enough?) That’s what Server-Rendered Multimedia Delivery is all about. Then, on top of this solid foundation, we look for opportunities to achieve higher server scalability by offloading media processing to the user device when possible. For example, since Adobe Flash content is so prevalent and the Flash Player consumes quite a lot of CPU, last year we introduced HDX MediaStream Flash Redirection to complement our existing Windows Media Redirection.

Even for Flash and Windows Media, server-rendered multimedia delivery comes into play when network latency is too high for Flash redirection or effective bandwidth is too low for Windows media redirection. The SmartRendering feature of HDX Adaptive Orchestration selects the appropriate technology based on the dynamic network conditions at hand. Likewise, SmartRendering recognizes if the user device is not capable of client-side rendering.

Server-side multimedia delivery also supports alternative media formats and players such as QuickTime and Silverlight. The user experience for these media formats over a high bandwidth connection is very similar to client-side rendering, "just like local". XenDesktop 4 supports an out-of-the-box frame rate of 24 fps (just like at the cinema) and can be adjusted to deliver a full 30 fps if required for certain demanding use cases.

So, how do you get the best performance out of server-rendered multimedia delivery? Here are my top three tips:
1. Configure Progressive Display to compress images in motion.
2. Use Branch Repeater when delivering video to remote locations.
3. Use the new High Definition audio codec

http://community.citrix.com/display/ocb/2010/03/22/Tuning+HDX+MediaStream+server-rendered+multimedia+delivery