Understanding how multimedia playback moderates network transfer speeds

Nick White — Mon, 27 Aug 2007 19:17:00 GMT

Mark Russinovich, one of our Technical Fellows and a prominent member of the Windows community, posted today on a topic that's received much discussion in the past few days -- that being the manner in which Windows Vista throttles network traffic on gigabit Ethernet networks when the user is engaged in multimedia playback.

As Mark puts it, "many people have correctly surmised that the degradation in network performance during multimedia playback is directly connected with mechanisms employed by the Multimedia Class Scheduler Service (MMCSS), a feature new to Windows Vista." This throttling of network traffic is mainly apparent on networks with infrastructure allowing gigabit throughput and is experienced by a user receiving, as opposed to sending, data.

The explanation is quite technical and rather esoteric, but the gist is that when receiving data on faster networks, the number of system interrupts is increased and because network-driven system interrupts are handled at higher priority than media playback, multimedia playback can be affected if the number of network-driven interrupts outpaces content refilling the multimedia playback buffer. Mark's full explanation is quite a bit more detailed -- I've only described it here in outline.

While this behavior is by design, the throttling parameters as shipped caused greater-than-anticipated degradation on gigabit Ethernet systems. In addition, there's also a related bug we've identified in scenarios involving multiple NICs but for which we're scheduling a fix. If you'd like all the details in their technical glory, visit Mark's blog. He'll have more news on this topic as it develops.

Windows Media Player on Firefox

Nick White — Mon, 16 Apr 2007 23:36:00 GMT

Have you been itching to enjoy your media content on Firefox? The Windows Media Player team put a lot of work into evolving media playback on Windows Vista through the new Media Foundation pipeline, and has also been actively monitoring feedback on WMP and playback in general. While commentary has been mainly positive for Web playback through IE, we've noticed that there's still work to be done to make Firefox users able to enjoy their media content on Windows.

We couldn't respond as quickly as we would have liked to (we had to get Windows Vista out the door!), but now that it's shipped, the team has moved its attention to getting Firefox users up and running. This week we are happy to say that we have a new plug-in for Firefox that makes WMP work once again -- and even better than it did before!

It's easy to get the new Firefox plug-in -- if you navigate to a Web page today that has the embedded WMP ActiveX control, Firefox will automatically grab the new plug-in for you to install and you will once again be able to enjoy your media content :)

Windows Vista Team Blog : Windows Media Player

Understanding how multimedia playback moderates network transfer speeds

Windows Media Player on Firefox