Streaming High Definition Video over a Wireless Network

With the Xbox 360 Flash Fall 2006 System Update, we've added support for WMV video playback from new sources.  If you've read the video format post, you'll see that your Xbox has the ability to playback high definition (HD) video encoded in the Windows Media Video 9 Advanced Profile (VC1) codec.  This means that you'll not only be able to watch High Definition video from external sources like a USB drive, CD, DVD, but also PC.

 

However, when you decide to stream HD content over your home wireless network, you might see performance degradation in the form of choppiness. This post is to provide you with some workarounds and suggestions to fix the choppiness.

 

Workarounds

Generally the performance degradation happens due to issues like interference, assuming you have an 802.11g router. The easiest, most cost-effective way to get around this is to wire your Xbox to your router via a LAN cable. Doing so will provide the best streaming quality bar none; although that probably was not the answer you wanted to hear.

 

A second (albeit more expensive) workaround is to purchase a router capable of 802.11a. Choppy video performance is likely due to either too much interference on your wireless’ operating frequency due to home appliances (i.e. the microwave, the cordless phone, or Bluetooth devices) or too much interference on overlapping g wireless channels.

 

802.11a has clear (non-overlapping channels) and operates on 5Ghz, a frequency that doesn’t have as many home appliances running within it, which makes it a better mode to stream anything that requires a lot of bandwidth. For more information on the differences between 802.11a and g, jump down to “802.11a vs. 802.11g.”

 

Through testing done by the Windows Media Center Team, it was determined that 802.11a is almost on par with 802.11g in terms of barrier penetration and range. Even so, it’s advised that you should only pass 802.11a through at most one wall for the best performance. If you still run into problems, even with 802.11a, you can read more about 802.11a drawbacks and an optimal environment by jumping down to “An optimal wireless streaming environment”

 

I wasn’t trying to stream HD content; I was trying to stream standard definition content over my 802.11b network!

You’ll probably notice that there wasn’t really mention of 802.11b in the workaround discussion. While it’s still a valid wireless mode, it’s the weakest of the three modes, capable of only providing ~6Mbps in ideal instances on an operational frequency of 2.4 Ghz. This mode will likely have problems even streaming non HD content, and is unable to stream HD content. If possible, for all content, use at least 802.11g which will give you good performance with standard definition content; 802.11a will likely give the best results for both standard and high definition content.

 

How do I know what wireless mode my 360 is connected to?

Start up your 360 without a game and it will boot to the dashboard. Go to the System Blade and scroll down to Network settings. Press A to see your Basic settings and you should see what 802.11 Wireless Mode your 360 is connected on be it a, b, or g.

 

802.11a vs. 802.11g

Yes, 802.11a and 802.11g have the same max throughput (25 Mbps not 54 Mbps as advertised due to WiFi being half-duplex communication technology). Streaming High Def usually requires about 19-24 Mbps, which means that your WiFi mode, be in a or b/g needs to be running at max throughput through the course of your video. Interference on a g network can compromise the performance of your WiFi network and thus cause degradation in performance.

 

The operational frequency of 802.11g is 2.4 Ghz, which is a common operating frequency for devices such as the microwave, all Bluetooth devices, and cordless phones. This means that if you have any of the above devices running, your home network could take a hit in performance due to the interference generated by your household appliances. The operational frequency of 802.11a is 5 Ghz which is a more uncommon operating frequency, mitigating it from interference caused by other devices.

 

IEEE 802.11 a/b/g all communicate in their respective operational frequencies by splitting their frequencies into several channels. A major difference between b/g and a is that the channels in b/g overlap, creating interference whereas the channels in a do not. In general, channel 1 on a b/g network overlaps with channels 2, 3, 4, and 5. This means that if your home network is on channel 1, but your neighbor’s home network is on channel 2, your WiFi signals may interfere, causing a degradation of performance for both networks (WiFi pollution). Contrast to this is 802.11a which has 12 clear channels meaning there’s less of a chance that you will incur a performance hit.

 

An Optimal Wireless Streaming Environment

We’ve found that optimal streaming performance occurs when you have either your PC or your XBOX connected to your router via a LAN and the other connected wirelessly over 802.11a. If you connect your PC to the router, then connect your Xbox wirelessly via Wireless Networking Adaptor to the 802.11a router or vice versa, do not connect both the PC and the Xbox to the router wirelessly.

 

Your 802.11a router should be in less than 20-feet with a clear line of sight to the device that’s connected to it wirelessly. This is especially important for 802.11a which theoretically has less range and worse material penetration than 802.11b or 802.11g.

 

The end goal is to reduce the amount of devices on the WiFi network to reduce any possible factors that might degrade performance.

 

Compiled by: Jun Ma (GT: shunsoku)

 

Sources

Netgear’s Wireless Networking Basics Manual

http://documentation.netgear.com/reference/fra/wireless/pdfs/FullManual.pdf

 

Wikipedia’s entry on Wireless Networking

http://en.wikipedia.org/wiki/Wi-Fi#Wi-Fi:_How_it_works