Streaming media formats: Windows Media Technologies (Netshow)
Microsoft's Windows Media Technologies for NT/Windows 2000 includes a comprehensive suite of authoring tools and streaming services for delivering audio, video, animation, and other multimedia over the Internet. Windows Media comes with a complete set of tools for encoding and authoring streaming content including Windows Media T.A.G.
Author, a utility for arranging media elements along a timeline. Windows Media presentations are played back with the Windows Media Player, which plays most local and streamed media file types including Advanced Streaming Format (Windows' native file format), MPEG, WAV, AVI, QuickTime, and RealAudio/RealVideo. Since Media Player is distributed with Windows, it has widespread distribution.
If you need a Windows NT 4.0-based solution, Windows Media Services offers several advantages:
- The Windows Media Server comes free
with unlimited streams with Windows NT Server 4.0 and later.
- It allows for better playback over
machines running Windows. To enable smooth multimedia playback over the Web
and avoid the problematic issue of cumbersome plug-in downloads altogether,
Microsoft is moving towards integrating Windows Media Player, along with
Internet Explorer, directly into the Windows operating system.
- Windows Media Server integrates with
Microsoft Site Server to enable pay-per-view and pay-per-minute billing
capabilities, usage analysis reporting, and personalized ad insertion.
- Tools for tracking behavior are
tightly integrated with the Windows NT Event Viewer and Performance Monitor,
making it easy for seasoned NT administrators to manage the Windows Media
Server.
- For multimedia content developers,
Microsoft provides helpful authoring tools. Creating a slide show of images
with synchronized audio can be accomplished by using the Windows Media T.A.G.
Author.
Compared to RealMedia, however, Windows Media has some serious drawbacks:
- It runs only on Windows NT/2000.
Many developers have reported problems with the stability of Windows NT for
mission-critical applications such as 24-hour live broadcasts. This can be a
show-stopper for those who demand the stability of Unix or Linux servers. In
contrast, RealNetworks supports NT as well as Linux, FreeBSD, Solaris, and
IRIX.
- It does not support Macromedia Flash
or the Synchronized Multimedia Integration Language (SMIL) standard, both of
which are supported by RealNetworks.
There are also some key differences in the way Windows Media and RealMedia encode and deliver multimedia content. With RealMedia, you can create multimedia presentations by using the SMIL markup language to connect various media elements together. These media elements are encoded as separate files: RealAudio, RealVideo, RealPix, RealText, QuickTime, MPEG, and so on. The RealServer, much the same way a standard web page is served up and delivered, then streams the presentation as separate media files held together by SMIL.
"Since G2 developers are creating multimedia presentations rather than simply encoding audio or video streams, the format has a new level of complexity," says Leah Goldberg, G2 media producer for CMPnet. "However, web developers have long been familiar with the flexibility and convenience of this approach to media delivery. The challenge with G2," Goldberg claims, "is working out the timing in the component RealPix, RealText, and RealFlash files. Since the idea is to synchronize all the different media elements together, working out the sub-timing issues within each of the component files can be quite complex."
In contrast, Windows Media wraps all media elements into one Active Streaming File (ASF), Microsoft's proprietary streaming media format. According to Microsoft, with ASF any object can be placed into an ASF data stream, including audio and video, scripts, ActiveX controls, and HTML documents with T.A.G. Author. This approach, similar to Flash and Shockwave movies, provides less flexibility in terms of updating and serving content, but it offers more stable client-side playback of various media elements and tighter authoring controls. For more information about creating ASF content, visit the Microsoft web site. Microsoft provides free code to members of its Developer Network.
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