The Silverlight Guru: Of Macs and Mobiles

If you've got questions about streaming with Silverlight—or anything related to Windows media video or audio—you've come to the right place. Ben Waggoner is Microsoft's principal video strategist for Silverlight and he's well-known to those who frequent industry conferences and forums. He's the source, and he's happy to address Silverlight questions large or small.

Ben Waggoner
For this series, we'll be fielding Silverlight questions from Streaming Media's readers and from the Streaming Media forums for Ben to answer. If you've got something you'd like help with, post to the forum or, even better, drop us a note at, so we can keep surprising Ben with questions he hasn't seen before.

Our first question was e-mailed from Barry:

I have a client who wants to use Silverlight but needs it to be viewable by pre-Intel Mac users. Do you know of any issues or workarounds? I was told that Pre-Intel Mac users will not be able to view Silverlight 2.0 streams.

You're right that PowerPC Macs can't stream Silverlight 2.0 content, says Ben, but did you know that they can stream Silverlight 1.0 content? And that there's usually no difference in the streams themselves?

Any PowerPC Mac running OS X 10.4.8 or higher is capable of viewing Silverlight 1.0 content. The difference between 1.0 and 2.0 is largely in the client features, such as the ability to view multiple streams at once. There are some differences in the streams—2.0 supports the WMA Pro as an optional audio codec, for example—but as long as you're using Windows Media codec 7, 8, or 9 and WMA as the audio codec, your streams will play in Silverlight 1.0 or 2.0.

That means you can deliver one set of streams, but simply offer different players for people who own older Macs and newer Macs.

Silverlight's new Smooth Streaming technology, which we covered in a recent feature, only runs on Intel Macs.

Our second question comes from Darla of Public Benefit Technology:

We currently specialize only in (very) long-form videos in WMV 9 with navigation and an embedded WMV 9 player, as streaming VoD for our clients. Should we switch these into Silverlight at some point?

These files are pretty sluggish on a Mac especially regarding the navigation, although they do very well on a PC. Would Silverlight do just as well as WM9 with the navigation and long form but also attain for us a far better Mac end-user experience?

Or, if it's not time to switch to Silverlight with this type file just yet, can we rely on Microsoft to take care of these many WM9 files already "out there" as streaming on-demand files, with our customers expecting them to be viable for many many years to come, with the navigation intact?

Yes, your Mac viewers would do better with a Silverlight client, says Ben, but there's probably nothing you need to switch over for the videos themselves.

"Ninety-eight percent of web WMV files out there will play in Silverlight," Ben says. The client player offers backwards compatibility for most WMV files, even long files such as yours. The viewer will enjoy better performance, including the ability to view multiple streams at once, and you'll be better able to customize the experience. The Windows Media Player users a five-second buffer, for example, which is difficult to change; shortening the buffer size is much easier with Silverlight.

The only way you'd need to reformat your library is if you're using the few codecs, such as WMA Voice, that aren't supported in Silverlight. Even DRM files will play. Add a PlayReady license, says Ben, and you're all set.

If you have more questions on moving to Silverlight, read this Silverlight migration guide, which Ben edited. He says it covers all the caveats.

Our third and final question for this month comes from Tong:

Do you have plans to port Silverlight into mobile devices in addition to PCs, and, if so, when?

Yes, says Ben, Microsoft announced in March, 2008, that Silverlight support would come to Windows Mobile and the Symbian OS. There's currently no publicly scheduled date for the release, so he can't say exactly when it will happen. Will it be part of the next big Windows Mobile update? "Silverlight is coming to Windows Mobile and it's not a part of the current 6.5," he says. "And I'll leave it at that."

Submit your Silverlight questions to Streaming Media’s Formats, Codecs, and Players forum, or send them directly to the author at

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