There are many pocketsize digital music players available, but they fall into two groups: Apple's iPod products and everything else.
IPods, the most popular music players with more than 70 percent of the American market, can play MP3 music files, a popular digital audio compression format. But for the most part, Apple steers its customers to songs in another format, called Advanced Audio Codec (AAC), which most non-Apple devices cannot play.
Apple's iTunes software, which runs on PC's and Macs, for example, automatically "rips," or converts, music from CD's into compressed AAC files for loading onto a computer or portable player. But users who want to convert tracks to MP3 files have to change the settings.
And downloads from Apple's iTunes Music Store come exclusively in a version of AAC that includes FairPlay, Apple's digital rights management technology, to prevent illegal copying and sharing of music. "One of the problems I see a lot is that people who are using iTunes-iPods have ripped their entire CD collection to the AAC format because that is the default setting in iTunes," said Grahm Skee, who runs the Web site AnythingButiPod.com, in an e-mail interview. "Now they are stuck with a format that can only be played on iPods."
At the same time, most of Apple's rivals use Microsoft's Windows Media Audio (WMA) format, which does not play on iPods. And most online music stores apart from iTunes - like Napster (napster.com), Wal-Mart (musicdownloads.walmart.com) and Yahoo Music (music.yahoo.com) - sell downloads in the copy-protected Secure WMA file format.
People whose tastes stray beyond the top 40 may have luck with eMusic (
http://www.emusic.com), which offers a large collection in the universally playable MP3 format. Many of eMusic's current top artists - Iron and Wine, Bloc Party and Devendra Banhart - are not household names like Kanye West and Coldplay, but they are popular among indie rock fans, who purchase more than 2.5 million songs a month, according to the company. EMusic is a subscription-based service, and its offerings start at $9.99 for 40 downloads a month.
Music fans can find a more mainstream selection, although less flexibility, with Rhapsody. Long a popular streaming service, Rhapsody began earlier this year to offer music files for outright purchase and subscription download. Songs purchased from Rhapsody use RealAudio 10's flavor of copy-protected AAC, but Real's Harmony technology can convert them to either Secure WMA or Apple's FairPlay version of AAC.
The WMA conversion is done with Microsoft's blessing. But converting to Apple's format is shakier. Apple changed the iPod's built-in program in October 2004 to prevent Rhapsody songs from playing on newer iPod models. Rhapsody updated Harmony in April so that its tracks can once again play on iPods. But that may change if Apple changes its iPod software again. Apple declined to comment for this article.
The safest strategy, and one popular among audio purists, is to purchase music on compact discs and rip it to the MP3 format.
CD's still offer the greatest selection. Some of the most popular music of all time - from bands like the Beatles, Led Zeppelin and AC/DC - is still unavailable from legitimate online stores.
Ripping CD's can also offer higher quality. ITunes and some other stores sell music encoded at a data rate of 128 kilobits per second. (EMusic, Rhapsody and Yahoo use 192 kbps.) Typical CD's are encoded at a rate of about 1,400 kbps. AAC and WMA use sophisticated data-compression technologies that allow them to maintain audio quality at lower data rates than CD's or even MP3's can, but no one claims that a 128 kbps download is equivalent to a compact disc.
Those who have already ripped a lot of CD's into either the Apple or Microsoft format have the option of converting their music from one format to another. ITunes software, for example, can find WMA files on a computer and convert them to AAC. Windows Media Player does not have a similar ability to change AAC to WMA, but other programs can handle this. For instance, Switch, a free program from NCH Swift Sound (nch.com.au) can convert more than a dozen audio formats, including AAC, MP3 and WMA.
The main drawback is that most formats require a data compression method that tosses out some audio information to make files smaller.
Quality deteriorates when ripping CD's to WMA, for example, then deteriorates further when converting the WMA file to AAC. And converters do not work on copy-protected files from online music stores - at least not without straying into troublesome legal terrain.
Some iPod owners, for example, use a program called JHymn (hymn-project.org/jhymndoc) to remove the copy protection from iTunes music downloads to convert or otherwise modify them without restrictions. The software also makes possible the sharing of copyrighted files, a use that JHymn's creators say they do not condone.
A federal law, the Digital Millennium Copyright Act, prohibits tampering with copy protection technologies. But JHymn's creators contend that the software, by allowing users to play songs purchased from iTunes on computers or devices that do not support Apple's system, merely enables a "fair use" allowed under traditional copyright law.
A JHymn representative, who goes only by the name FutureProof, however, acknowledged that using the software would almost certainly violate Apple's terms of service for iTunes.
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