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Distribute Expertise: Flash vs. Silverlight

Jun 1, 2008 12:00 PM, By Jan Ozer

Which platform will suit your web-development needs?

Players and codecs

In 2006, I wrote several codec-related case studies focusing on why companies chose different streaming technologies. One of the more fun case studies involved ESPN, a site that uses Flash as a player/codec because it was ubiquitous and customizable. It also allowed the company to design an easy-to-use player that integrated its branding and provided optimal presentation of other content.

Back then, Flash was the only technology that offered more than the bare minimum of player customization. Probably the most fundamental feature of Silverlight is the easy ability to select and customize a player, much like you can do in Flash. Specifically, when producing your video in Microsoft Expression Encoder 2, you can choose among a variety of player templates and also insert chapter points and captions into your videos (see Figure 3). After producing the template, you can use it as is or customize it further in Expression Blend 2.

Throw in the currently free Silverlight Streaming Service, and Silverlight presents a very strong product offering for casual producers without programming resources or budget for same. While you can customize the Flash player and add chapter points and captions, you can't perform these functions in the Flash encoder; you have to use Flash itself, which is much more challenging. Currently, Adobe offers nothing that competes with the Silverlight Streaming Service.

In addition, Silverlight's customizability should be of great interest to all current Windows Media producers, because it lets them create a more attractive, easier-to-use player than the Windows Media Player they're currently using. A good example is the beta version of the Silverlight player, which will be used to broadcast the summer Olympics.

There are many factors beyond customizability to consider when choosing a player (see Table 1). Supported platforms is critical, and both Silverlight and Flash support Windows, Mac, and Linux platforms — Silverlight via an agreement with Novell. Flash adds Solaris support, which is important for those targeting highly technical viewers, but that's obviously not a critical consideration for Entertainment Tonight's website.

As mentioned above, one of the advantages of Silverlight over the Windows Media Player is that it's a much smaller download. Although it is still almost three times larger than the Flash Player, at 4.3MB, it's a short download for the broadband customers that most rich-media sites are targeting.

Penetration measures the percentage of viewers on the available platforms that have downloaded the respective player, and Flash shines here with an overall penetration rate of 98 percent — 62 percent of which were H.264-capable. Not surprisingly, in March 2008, research firm comScore reported that 75 percent of online videos are viewed with Flash technology, making Flash the number-one format for video on the Web.

In contrast, Microsoft hasn't released Silverlight's penetration rate, but the company claims downloads of 1.5 million plug-ins a day. Irrespective of download size, forcing a visitor to download a plug-in to view your site's content involves a risk, however slight, that they'll decline and surf away. Today, this makes Silverlight a riskier solution.

Another important factor is the quality of the codecs available on the respective platforms. As you can see in Table 1, Flash supports both the On2 Technologies VP6 codec and the H.264 codec (as well as older codecs such as Sorenson Spark). Silverlight supports Microsoft's Windows Media Video codec, which is the same as VC-1. It's important to note that Silverlight introduced no improvement in VC-1 compression quality.

One developer that I spoke with — Kyle Snarr of Struck Creative, an award-winning web-design firm in Salt Lake City — felt that H.264 support was a big asset for Flash, because it allowed the company's clients to deliver higher-quality video at a lower data rate. Snarr wasn't concerned that only 62 percent of the Flash-installed base could play H.264 video, because Struck's clients — including DeBeers and GM — assume that users will have fairly robust, up-to-date systems, and because the websites that Struck Creative designs always make it easy for visitors to update to the necessary plug-ins.

Regarding codec quality, in May 2008, I compared VC-1's quality to H.264 and two versions of On2's VP6 — the currently shipping version and a newly introduced beta version that On2 claimed improved compressed quality by about 40 percent. For my tests, I produced SD and HD test clips using the old and new versions of VP6, H.264 video using Rhozet's Carbon Coder, and VC-1 video produced by Microsoft's Expression Encoder 2.

© 2008 Penton Media, Inc.