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Windows Media Audio

October 1, 2000
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Microsoft ups the ante in streaming audio.When the computer industry's 500-pound gorilla turns its attention to streaming audio, you just have to stop and listen. Microsoft has introduced the latest version of its streaming media technologies, promising, among other things, significant reductions in file size with improved audio performance.

Windows Media Technologies (formerly known as NetShow) is a set of components that handles the preparation, delivery, and playback of audio and video. The audio component, Windows Media Audio (WMA), is Microsoft's newest codec for wringing more audio quality out of fewer bits. As usual, Microsoft has covered all the bases, offering Windows Media Tools for encoding audio and video, Windows Media Services for distribution, Windows Media Digital Broadcast Manager for e-commerce, and Windows Media Player for end-user playback (see Fig. 1). Before the sheer repetition of the name gives you the same tic it's given me, let's just say that for anyone trying to pump music through the still-inadequate cyber pipeline, WMA is definitely a step in the right direction.

SQUEEZE ME, PLEASE MEIn the wide world of Web audio, two things matter above all else: quality of sound (at a given bandwidth or file size) and ease of playback. If everyone's modem could support a CD-resolution stream of 705,600 bps (bits per second), there would be no need for data compression. Audio would come through in its original glory, and our systems wouldn't require proprietary playback codecs. With most users stuck at 56 Kbps or lower, however, we can count on less than one-twelfth of the bandwidth we'd like to have.

Whittling the bitstream down to a manageable size is achieved through a type of data compression called frequency coding or perceptual coding. Sophisticated algorithms analyze the audio to determine what our ears will miss the least and discard it. Because some information is lost in the process, this is known as "lossy" compression. The most prevalent forms of lossy audio compression on the Web are currently RealNetworks G2, MP3, and WMA.

All three compression schemes are capable of delivering high fidelity at low compression ratios, but the more you squeeze the audio data, the more obvious the "lossiness" becomes. Telltale signs include diminished high- and low-frequency response, graininess, and a swirling sound not unlike the effect of a phase shifter or ring modulator. Each new generation of encoders further reduces the side effects of frequency coding, and the current version of WMA continues the trend.

HYPE, HYPE, HOORAY?Microsoft's marketing machine boldly claims that WMA produces "sound quality at 22 Kbps that is roughly equivalent to G2's audio quality at 44 Kbps streamed, and it produces files that are half the size of equivalent-quality MP3 files." Of course, these are the same reality-challenged folks who keep telling us that the latest version of Windows is faster, easier, and more dependable than the last, so I was understandably skeptical about this claim. After careful listening tests, however, I was pleasantly surprised.

The comparison to MP3 is hard to argue with, especially when listening through typical computer speakers. At 64 Kbps, WMA exhibits little if any "swirl" and matches the reasonably smooth character of MP3 at 128 Kbps. At its highest bit rate of 96.7 Kbps, G2 achieves very similar audio quality. I would bet that most people listening through most common car stereos, boom boxes, or portable headphones would find it hard to distinguish audio encoded at these bit rates from the original source. At 128 Kbps (MP3's 10:1 data compression ratio), this is impressive enough, but at 64 Kbps, WMA manages better than a 20:1 ratio.

Microsoft's claims for WMA versus G2, however, are slightly overstated. At comparable bit rates, WMA did indeed sound better than G2, but it did not sound "roughly equivalent" at half the bit rate, in my opinion.

I encoded and auditioned clips in a variety of musical styles at 22 Kbps and 32 Kbps settings: typical for 28.8 and 56 Kbps modems, respectively. At these lower bit rates, the differences between the compression formats became readily apparent. MP3 sounds the worst by far at low bit rates, with the swirl and grit spoiling the music in a hurry. G2 at 32 Kbps, on the other hand, is pretty listenable. The frequency response seems comparable to AM radio, which makes this combination a perfectly viable medium for "taste-testing" new music. Given the proliferation of Web radio sites, plenty of people also find it adequate for background listening.

While WMA failed to match G2 at half the bit rate, it did sound clearly better at the same bit rate. There was less phasing and a much broader tonal spectrum. The music sounded more real and maintained some of the bottom end that is usually so decimated by frequency coding. For me, WMA at 32 Kbps turns the corner from tolerable to enjoyable. To put it in perspective, I have more than once put up with bad-sounding radio reception for an extended period if I was really interested in the music.

If you have to encode at 22 Kbps, Windows Media Audio does help, but it's still not a great choice for musical purposes other than auditioning music before buying it. While WMA's improved frequency response fills out the sound, it's still pretty rough. On the other hand, it's miraculous that you can even recognize music that is squished down to 11/467 of its original size. A 30-second clip that started out at 5 MB is only 80 KB at the 22 Kbps setting! If you have no choice but to squeeze your music through the eye of a needle, WMA is for you.

WE ARE BORGMicrosoft has thought of just about everything, assimilating the diverse functions of G2 and MP3 into a single creation-to-destination package. It has been common for online music lovers to audition new music via 32 Kbps RealAudio streams and then download 128 Kbps MP3 files for playback on their computers or portable MP3 players. Musicians hawking their wares online have had to encode, upload, and present their music in both formats.

To accomplish the same thing with WMA, bands may still want to use a lower bandwidth, such as 32 Kbps, for streaming samples, and a higher bandwidth, probably 64 or 128 Kbps, for download. They still have to manage two versions of the file, but will only have to deal with a single file format. Instead of using products from different companies to encode the files into different formats and then using RealNetworks' RealPlayer or Nullsoft's Winamp to play them, you can use Windows Media On-Demand Producer to encode both versions and Media Player to play both. What's more, dozens of companies representing many of the most popular audio players have already licensed the Windows Media Audio format, including Nullsoft, MusicMaker, Yahoo, and even RealNetworks. This widespread support should make it even easier for you to distribute your music online.

The impressive Windows Media On-Demand Producer utility (see Fig. 2) was developed by Microsoft and Sonic Foundry. It devours audio and video files and spits out Windows Media files. It can even generate HTML templates to simplify the publishing process. All you have to do is open a file and push the red button, and a wizard prompts you for bit rate, destination directory, and file name. I rarely find such wizards useful, because they often don't work, take too long, or don't cover the specific needs of my project. Happily, the On-Demand Producer team got it right, and the encoding wizard is simple, quick, and useful.

You can even encode multiple files in a single process, although you can't encode a group of files at mixed or multiple bit rates in a single pass. On-Demand Producer makes child's play of trimming a file and adding fade-ins and fade-outs. To change the beginning or end of a file, simply drag the yellow marker. To fade in or out, drag the red marker. You can zoom in to the sample level, add markers, and embed commands or text, including closed captions. Microsoft and Sonic Foundry couldn't have done much more to make encoding WMA files easier, and the best part is that On-Demand Producer is free.

Speaking of free stuff, I also tried out the new Windows Media Player 7 (see Fig. 3). It's big, it's slick-looking, and it wants to manage all of your audio and video files. It plays audio CDs, looks up artist and album information online, and even extracts CD audio tracks and converts them directly into WMA files. You can then use the program to load the resulting WMA files into a compatible portable player. New features include the ability to burn audio CDs from WMA and MP3-based content, and the new player also offers artists the option of allowing secured content to be burned to CD. What's more, the new version lets you create Content Packages: a kind of boxed set that includes graphics and audio in a single download. That means you can add such things as cover art, lyrics, Web site addresses, and even video clips to your works when you distribute them.

Media Player 7 also lets you create and manage playlists of audio and video files, and it keeps track of your Web radio stations. As if that weren't enough, it also looks cool. As with RealJukebox and Winamp, you can select from among a couple dozen "visualizations," which are more or less graphic permutations of a waveform display, and you can dress up Media Player in different "skins" (see Fig. 1).

Giving anyone the ability to transfer digital media so easily, however, is a double-edged sword, and Microsoft has included tools to give artists some chance of receiving financial compensation for their work. Windows Media Rights Management is an SDMI-capable mechanism that encrypts files to enable authors to track and license playback. (SDMI stands for Secure Digital Music Initiative.) Support for e-commerce and pay-per-view scenarios is also provided.

THE WORLD WILL BEAT A PATHThird-party support for WMA is growing quickly, and Microsoft's list of "coming attractions" is impressive. Products from Sonic Foundry and Cakewalk already support the new format, and other companies are jumping onboard as the demand grows. Version 6.3 of Media Player for Macintosh is currently in beta release, so Mac-based end-users will be able to take advantage of WMA. Mac-based producers of audio content aren't quite so lucky, though, as On-Demand Producer is currently available only on the PC.

One of the driving forces behind the MP3 explosion is the proliferation of Rio-style portable playback devices. WMA has its sights set on such players; according to Microsoft, the next generation of many of these players will support WMA, including Diamond's Rio 600, RCA's Lyra, Creative's Nomad II, and Sony's VAIO Music Clip.

Microsoft has also built support for WMA into its Windows CE handheld-computer operating system. Now CE-based PDAs are poised to do double duty as portable music players. Palm-sized PCs from Casio, Compaq, and Hewlett-Packard already natively supports Windows Media Audio.

A number of major music Web sites have announced support for WMA as well, including giants Sony, BMG, and EMI. Microsoft has also launched its own site full of multimedia content, called - surprisingly - WindowsMedia .com. Liquid Audio is building WMA support into its online offerings and the next major version of its multiformat player, and House of Blues is broadcasting concerts in WMA alongside RealAudio.

RealNetworks commands about 80 percent of the streaming audio market, and anyone on the planet who doesn't know how to play an MP3 file on their computer knows a 12-year-old who does. Nevertheless, Windows Media Audio stands a very real chance of upsetting the apple cart, especially when you consider WMA's improved audio quality, easy implementation, and Microsoft's knack for getting major players on its bandwagon. The fact that RealNetworks is releasing version 8 of its product line without any improvements in its audio characteristics gives WMA an additional boost.

CALL THE ATTORNEY GENERAL!I must admit that it's impressive and startling to see Microsoft roll out something as comprehensive as Windows Media Technologies. The company had the foresight as well as the resources to cover all the bases and to do it in a single stroke. Those looking for a way to present and distribute music online hardly need to look beyond WMA. With a free high-quality encoder, a new codec that covers the ground previously split between RealNetworks G2 and MP3, support for digital rights management and e-commerce, a free playback browser plug-in, and growing support in consumer devices, it's as close to a complete solution as you can get.

As a musician preparing material for online distribution, it's great to have this sort of one-stop shopping. At the same time, you have to wonder what the Windows Media juggernaut will do to the lively competition that has brought streaming audio so far so fast. The one thing that's certain is that WMA has succeeded in upping the ante for compressed audio quality in both streaming and downloadable applications, and that's a good thing.

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