A: There are three widely used formats, MP3, AAC (Advanced Audio Coding), and WMA (Windows Media Audio). All are proprietary in the sense that the makers of software and hardware players must obtain licenses from the owners of the technology.
MP3 is the most broadly compatible. Except for some Sony (SNE
) models, all players that I know of can handle it. iPods can also play AAC. Most other players can handle Microsoft's (MSFT
) WMA as well as MP3.
The actual music-encoding format is only part of the story. There's also the separate issue of the various digital rights management (copy-protection) schemes used to protect commercially downloaded music. All music legally downloaded, except for some tracks made available by mostly indie artists, is copy-protected. But if you rip a CD in Windows Media Player, it's in WMA format by default, and you can't play it on an iPod.
) iTunes rips to the AAC format by default. Songs purchased from the iTunes Music Store are protected by a scheme called Fairplay and work only on iPods. WMA with Microsoft's Janus is widely supported on other players including any that bear Microsoft's PlaysForSure logo.
LOCKED IN. RealNetworks (RNWK
) presents the most complicated situation. Music purchased from its Real.com service uses Real's own Helix copy protection, which isn't widely supported on portable players. But music downloaded from Rhapsody, also owned by RealNetworks, uses Windows Media with Janus.
There are lots of technical arguments about the virtues and flaws of each of these formats and protection schemes, but it's really all about locking users into certain services and devices. The net effect is to make things very confusing for consumers.
For recent reviews of music download formats see BW Online, 5/19/05, "Microsoft in Fast Forward Mode"; 5/23/05, "WinAmp Still Loves the '90s"; and 5/26/05, "RealPlayer: Master Music Manager". Wildstrom is Technology & You columnist for BusinessWeek. You can contact him at firstname.lastname@example.org