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June 1998

Microsoft Systems Journal Homepage

Editor's Note

Before we expound on this month's trendy tech tidbits, we want to vent on the use of codenames and acronyms. We vote for the entire elimination of codenames. If we told you we could double your hard disk space, you'd go for it. So why not double the available gray matter upstairs and take up only one cell per actual product name? We urge everyone, especially Microsoft, to stop the endless coining of abstract, content-free codenames like Poseidon, Tiramisu, Sequoia, and Gdansk. Plain old descriptive names like Windows 98 suit us just fine, thank you.
And stop it already with the million and one acronyms. We predict a multiletter acronym shortage (MAS) before the Year 2000 (Y2K) bug strikes. Here are a few more to push us to the brink of madness. Since 1990 we've all grown to love the Audio Video Interleaved (AVI) file format. In early April, Microsoft (MS) announced two new multimedia (MM) file formats destined to replace the AVI file format in your MM repertoire: the Advanced Streaming Format (ASF) and the Advanced Authoring Format (AAF). Both the ASF and AAF specifications were developed with the open collaboration of some of technology's leading members. Fine. Just what are these formats and why should you care?
Oversimplified, ASF—the format presently used by NetShow and the Windows NT multimedia streaming service—is a set of rules that dictate how data should be laid out on disk to be optimized for both delivery and playback.
ASF offers extensible and scalable media types, component download, stream prioritization, multiple language support, environment independence, and rich interstream relationships. ASF will utilize the Real-Time Protocol (RTP), the Real-Time Streaming Protocol (RTSP), and the IP Multicast protocols. The ASF 2.0 Preliminary Developer's Kit (PDK) is available now on the Web.
AAF deals with the actual media data itself. AAF is described as "a structured container for media and metadata that provides a single object-oriented model [we read this as COM, COM, and more COM; but then again what isn't COM these days?] to interchange a broad variety of media types including video (AVI), audio (WAV), still images (BMP, GIF, TIF, JPEG, and so on), graphics, text (TXT), MIDI files, animation, compositional information, and event triggers."
Why do current file formats need replacing? Because they're not cross-platform and editing often means entire file rewrites. AAF's version control capabilities allow an AAF file's data to be edited and revised while retaining the history of the changes such that an older version of the file can be recalled, if necessary. Composing a complex multistream and multilayer presentation is out of the question with most current file formats. Indeed, MM composition today involves the laborious use of multiple tools, and too often quality must be sacrificed for expediency. Also, existing formats often cannot reference other files that may be required from a different directory or over a network.
Content tool developers or gamers should therefore check out the AAF Software Developer's Kit (SDK) when it's released in the second half of this year.
After satisfying your MM thirst with this month's DirectX coverage by Jason Clark, if you want further information on ASF and AAF, take a look at As for the heartbreak of MAS, maybe we can simply start recycling acronyms—in LIFO order, of course!

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