The Silverlight Guru: Silverlight 3 Sneak Peak

Usually in this space Ben Waggoner, Microsoft's principal video strategist for Silverlight, answers questions from you, the reader. But this is no ordinary day. With the release of Silverlight 3 tomorrow, we wanted to do something special.

Ben Waggoner
We talked to Waggoner about the best features in the new version, to learn how they'll improve the Silverlight experience and find out what you need to know about them. If you have questions about Silverlight 3, send them to, and Waggoner will answer them next month.

"One of the classic complaints about Flash forever and even Silverlight to some degree is it stutters, or it makes my fans run so loud on my computer that I can't hear the audio," says Waggoner.

Silverlight got a general tune-up with this release to ensure that it doesn't drop any frames and that viewers get smoother playback experiences.

"Also, we're adding in GPU [graphics processing unit] support for scaling and compositing," Waggoner says. "Some people call it GPU video acceleration." That means Silverlight offloads video stretching and other playback functions to the GPU so that the CPU (central processing unit) can focus on video decoding.

Surprisingly, this release lowers the usage requirements so that a lot more computers can handle Silverlight. "I'd say overall the amount of machine required to play back a particular level of Silverlight experience goes down by about two-thirds," says Waggoner, noting that even most netbooks will be able to play Silverlight-based videocontent.

MPEG 4 Support
"We're adding support for MPEG 4, H.264 video, AAC audio in Silverlight 3, so pretty much any .MP4 file which uses H.264 exported from QuickTime, every iPod/podcasting/AppleTV-compatible file is now Silverlight-compatible, too. Almost all the F4V files for Flash are also Silverlight-compatible," says Waggoner.

The benefit of that is that companies with a library of Windows Media assets and a library of MPEG 4 assets will now be able to use a single player to show everything they have. They'll be able to offer viewers a single player experience.

"A lot of companies out there have big libraries of stuff, and we'll be able to interoperate with that," says Waggoner.

Raw AV Pipeline
"That's a name that clearly engineers thought of," jokes Waggoner. While it sounds complex, it's simply a way to extend the Silverlight model to a wide variety of other media formats and codecs.

"Silverlight uses managed code. It's not a scripted language like JavaScript, but it's like the original Java where you would write a language and then compile down to some managed code. It's a just-in-time compiler that's actually quite fast in terms of performance. We're able to do a whole lot more math every second due to having this whole managed code layer from .NET," says Waggoner.

"We're actually enabling video and audio codecs to be implemented in that model. You can actually then support arbitrary file formats, protocols, and video and audio codecs in the managed code," he says.

The benefit for developers is that they can build in support for other formats using the managed code, in order to extend what Silverlight can handle.

How will this be used? Waggoner says some guys from Novell are creating an Ogg Vorbis decoder, for one. There'll be nothing for the user to install, and no difference for a supported codec and a managed codec; viewers will simply enjoy smooth playback.

Out-of-Browser Playback
With Silverlight 3, you don't need to always launch your browser to see a Silverlight video, since you'll have the option of running Silverlight from your desktop.

"Now, we optionally have an out-of-browser Silverlight app. We just add a little button to your app that says 'Hey, I want to actually save this as an application.' What it'll do is it'll save your Silverlight application, even add it to your dock on a Mac or add it to your start menu in Windows, or your desktop either way. Instead of having to launch a Web browser for Silverlight, you just click on it. It's stored locally and launches there," says Waggoner.

Working with local Silverlight content is safer that local Adobe AIR content, claims Waggoner, because the Silverlight content works in the Silverlight secure sandbox and can't harm other files. With Adobe AIR, he says, someone could write a malicious bug that would erase files on your hard drive.

"It's still the full Silverlight security model," says Waggoner. "It just doesn't require a browser to be wrapped around it."

If you save a Smooth Streaming video to your desktop, you'll get the highest possible bitrate. The ability to save content works with all types of Silverlight applications, such as games or quizzes, so it's not only for video.

To read more about the new version of Silverlight or to download software, go to Microsoft's Silverlight site.

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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