Auditioning high-resolution surround-sound compression

摘要

This article and its companion Web-site addendum are the culmination of a several-month project that digs into the inner workings of today's most prevalent high-end audio compression technologies (references 1, 2, and 3). It focuses on audio containing more than two channels and having per-channel samples larger than 16 bits, sampling rates greater than 48 kHz, or both, and I investigate Dolby Labs' AC-3 (also known as Dolby Digital), DTS' (Digital Theater Systems') Coherent Acoustics, and Microsoft's WMA (Windows Media Audio) Professional algorithms. I intend not to assess how well the algorithms preserve the sonic qualities of real-life music and other complex sounds; only your ears can make that determination (see sidebar "WAV woes" on the Web version of this article at www.edn.com). I instead attempt to show how the algorithms respond to a set of carefully crafted test clips; from these results, you should be able to draw some conclusions about how the algorithms perform their bit- slimming magic tricks.