The Right Profile
Love it or hate it, Microsoft’s Windows Media Video plays a major role in corporate and broadcast streaming. For example, in an informal survey that I recently compiled, nine of 14 corporate sites used Windows Media Video, along with seven of the 16 broadcast sites. In the last few months, Microsoft has released updated codecs and enhanced access to Windows Media-related encoding parameters that enable streaming publishers to improve the quality of Windows Media Video.
This article describes what’s new from Microsoft and how to get it, and examines how much video quality has improved over previous versions. And, since Windows Media doesn’t live in a vacuum, I’ll also describe how Microsoft’s video codec compares in quality with Flash and Apple’s H.264 codec.
Two additional article components will be available on the web: First, a brief interview with Ben Waggoner, program manager for video encoding at Microsoft; and second, as a counterpoint, a short interview with Chris Hock, group product manager for Adobe’s dynamic systems group.
What’s New from Microsoft
What’s new are updated codecs released in November 2006 with Windows Media Player 11. In his article, "Best Practices for Windows Media Encoding" (2007 Streaming Media Industry Sourcebook, pp. 122–128), Ben Waggoner described how to get those codecs, which ship with Microsoft Vista and can be accessed by updating to Windows Media Player 11 or by installing the Windows Media Format SDK 11. Waggoner details the relationship between VC-1 and Windows Media 9 in that article, and also in the interview available on our website. To make sure we’re on the same page, let me summarize them here.
VC-1 is the SMPTE (Society of Motion Picture and Television Engineers) designation for the Windows Media Video codecs standardized by that group for use with HD DVD and Blu-ray Discs. Any company can make VC-1 encoding available in their products by licensing the technology from the MPEG Licensing Authoring organization, or MPEG LA, which pays royalties back to the 15 companies in the VC-1 patent pool. To be clear, Microsoft doesn’t control VC-1; they’re part of the patent pool.
In contrast, the Windows Media 9 codecs are VC-1 compatible, but are controlled by Microsoft. There are two main codecs within the group: the Windows Media Video 9 codec, which includes the Simple and Main Profiles; and the Windows Media Video 9 Advanced Profile (WMV-AP).
Historically, most web encoding has used the WMV 9 Main Profile, with the Simple Profile reserved for CPU-challenged devices like cell phones and PDAs. The critical differences between the Main and Advanced Profile relate to support for interlaced formats and other requirements of IPTV and high-definition DVDs. For those interested, Wikipedia has a great chart detailing the components of the three profiles, available at http://en.wikipedia.org/wiki/VC1.
There are a couple of key points to note about the WMV-AP codec. First, since the main differences relate to support for interlaced formats, it delivers very little quality benefit for traditional web-based video. As I’ll discuss in more detail below, you won’t see a noticeable increase in quality between a file encoded with the Windows Media Video 9 codec, or with the WMV-AP.
To view WMV-AP files, you’ll need the latest codec update for Windows Media Player, which works with Media Players going back to Version 9. That’s fine, but I was disappointed the update didn’t work with 6.4 (mplayer2.exe), because this is the last version of Media Player that lets you open multiple instances of the player so you can play or view multiple Windows Media (or AVI or MPEG) files simultaneously. To view these files on the Mac, you’ll need the latest Flip4Mac plugin update, version 2.1.1, which wasn’t available at the time I wrote this.
Where’s The Beef?
OK, if the WMV-AP codec itself doesn’t deliver improved quality, then what’s the point of the new version? First, Microsoft claims that the updated codecs shipped with the Version 11 SDK will improve compressed quality, even if you don’t use the Advanced Profile, or the additional techniques discussed below.