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Live Streaming Summit [7-8 May 2019]
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Microsoft Smooth Streaming: The Best of Both Worlds?
Announced last fall and released last month at NAB, Microsoft's Smooth Streaming seeks to combine the advantages of streaming with the simplicity and ease of use of progressive download.

Microsoft released a hybrid delivery system know as Smooth Streaming at the National Association of Broadcasters (NAB) show this year, bringing a rich and engaging HD experience to online video.

Combining the ease of progressive downloading with the benefits of streamed content, Microsoft has created an adaptive streaming format that's easy to implement and offers viewers a rich video experience. While mass adoption is still several months off, we're impressed with the tests we've seen.

Progressive Vs. Streaming
Progressive downloads constitute most of the video on the Web—80 to 90 percent, according to Steve Sklepowich, group manager for Silverlight Media—including that from YouTube, Vimeo, and MySpace. Progressive downloads work with standard web servers, and the client can begin playing the file before it's finished downloading. Progressive downloads are widely supported, but wasteful to the content publisher, since they often send more video than will be watched.

Traditional streaming sends video in real-time and is used for live events. It requires a media server, so it's more expensive, says Sklepowich, but it only sends the content that the viewer will watch, with little buffer. The disadvantages are that it isn't scalable, viewers often encounter buffering delays, and some live events have failed when limited numbers of dedicated servers were overloaded.

The Hybrid Advantage
With Smooth Streaming, Microsoft is radically changing its approach to online video. "Before we tried to adapt the web to be more like streaming, and now we're trying to take the benefits of traditional streaming to the web," says Sklepowich. Rather than offering proprietary formats for proprietary servers, Smooth Streaming works over standard servers with files built on MPEG-4 and AAC formats.

"It shows that Microsoft is supporting things outside its own ecosystem, which is really important," says Christopher Levy, CEO of BuyDRM, which has long been a Microsoft partner and offers DRM solutions for both Smooth Streaming and Silverlight.

Smooth Streaming was first announced in October 2008, as an extension for Microsoft's Internet Information Services (IIS) 7.0 release. The "aha!" element that makes this a hybrid delivery method is that it works over HTTP but it delivers only the needed content to the viewer by breaking the stream into discrete chunks. It also allows for automatic bandwidth switching, so that the viewer gets the highest resolution possible at any moment.

A video prepared for Smooth Streaming is encoded into several different bitrates, with each bitrate its own file. The client requests two-second sections of the video one at a time, and the server sends chunks taken from the larger file. Because the multiple bitrate versions are saved as one file each, they're easier for the host to store. But because they're broken up as needed, they come to the client as multiple files.

This delivery method makes it easy for both the client and server to switch to a different bitrate file when needed. Only five seconds of video is cached in the client's browser. When the CPU is unable to handle higher resolution files or there's increased traffic, the client and server automatically switch to a lower resolution file. When more bandwidth is available or the CPU is able to handle more, a higher resolution file is sent.

As Smooth Streaming files are viewed and chunks of video are cached on networks, the client often won't need to go all the way back to the original file to grab the next segment: It will be able to reduce traffic by grabbing files from a nearer source. This is the primary difference between Smooth Streaming and Adobe Flash Dynamic Streaming, says Sklepowich, since the Adobe solution always needs to return to the original server to grab a new file.

The other adaptive streaming technology on the rise is H.264 scalable video coding, which we covered last month in this article.

Take a look at this test file to see Smooth Streaming in action. It allows for user-controlled bandwidth throttling, to simulate network activity. Drag the slider in the upper right corner to a new position and, after five seconds, you'll see that a new bitrate file is being used. What you won't see is a buffering delay (as long as your system can keep up with the lowest bitrate stream): the switch is completely seamless.

Silverlight Benefits
Silverlight's improved quality and delivery should translate into a variety of revenue opportunities. For one, notes Sklepowich, viewer engagement is way up with Smooth Streaming video.

"We're finding that engagement times are blowing away what you could do with either traditional streaming or progressive download," Sklepowich says.

A more TV-like experience and viewers staying put for around 50 percent longer means that Silverlight should be more attractive to advertisers. Subscription offerings using DRM should also gain ground, says Sklepowich.

As the first company to offer Silverlight DRM, BuyDRM has a two-month lead on the competition, Levy claims. He's impressed with "how Microsoft has changed the direction of revenue opportunities with Silverlight and IIS7 and Silverlight DRM, moving away from giving away or licensing for negligible fees proprietary technologies with limited scope and instead moved towards licensing technologies for a fee with much broader scope and usability in the marketplace [i.e. H.264/AAC/MPG4, support for all browsers and Mac and Linux] and believes it will lead to a broader customer base."

"The big message is Mac support. It's been too long, and now that we have Mac support we think that's a really big piece," Levy says. He thinks that it will take six months for the CDNs to build up a Silverlight infrastructure, but when they do the studios and major video sites will follow. Broadcasting the Olympics in Silverlight is a great promotional item, but he says "It'll take a YouTube or a Hulu to make Silverlight a mainstream product."

When that happens, the online TV experience will have taken a giant step forward.