Facing the Codec Challenge

The steady progression of compressed digital audio into all sorts of places (do you really need to listen to Mozart on a PDA?) is raising all sorts of issues. But none is more important to readers of Sound & Vision than the ability of the codecs - the encode/decode software - to faithfully reproduce music after compressing CD tracks to file sizes that can be easily downloaded or stored. Do any of the popular codecs really achieve "CD quality" sound? Can Windows Media Audio (WMA) provide CD quality at the relatively low data rate of 64 kilobits per second (kbps), as Microsoft claims on its Web site, or even equal the sound quality of the de facto 128-kbps MP3 standard?

To find out, we held a third round of scientifically controlled, critical listening tests (the previous rounds appeared in the September 1999 and September 2000 issues). We were particularly interested to see how the latest version of WMA would fare relative to MP3, since our earlier tests used a now-obsolete version of WMA that didn't do all that well. Because RealOne Player software is very popular on the Net, and the RealAudio 8 codec in the current version incorporates Sony's ATRAC3 (used for Memory Stick devices as well as the MiniDisc Long Play format), we decided to include it, too, in this round of tests.

Test Graphs