Creative has dominated the market for hardware-accelerated positional 3D audio for years, in part because the company succeeded in buying out its most credible rivals, but also because it's largely managed to lock competitors out of EAX environmental audio extensions that most games use for 3D sound. At best, sound cards that lack Creative audio chips are limited to supporting EAX 2.0—a technology that dates back to the SoundBlaster Live! and can only handle up to 32 concurrent voices. The latest version of EAX numbers 5.0, bringing with it support for up to 128 concurrent voices at high-definition sampling rates and resolutions.
Given the exclusive status of higher EAX versions, we were surprised to see Asus' recently announced Xonar DX sound card claim to support "EAX 5.0 sound effects." That card uses a version of the Oxygen HD audio chip made by C-Media, so it definitely doesn't have a Creative audio processor onboard. We weren't surprised, then, when Creative VP of Corporate Communications Phil O'Shaughnessy contacted us disputing Asus' claims. According to O'Shaughnessy, the Xonars do not support EAX versions 5, 4, or even 3. The cards, he says, are "falsely reporting EAX 5 capabilities" and failing to deliver a "genuine EAX Advanced HD experience." Touché.
We passed Creative's response over to Asus, which responded in detail explaining how the Xonar deals with DirectSound 3D audio and EAX. Both are handled by a new version 2.0 of Asus' DirectSound 3D Game Extensions (DS3D GX) primed to support 128 voices with enhanced reverb effects for "most" DirectSound 3D games, including those that take advantage of EAX 5.0. DS3D GX works by intercepting DirectSound 3D and EAX calls generated by games and redirecting them to Asus' own audio processing engine, which then attempts to mimic the intended effects.
Asus says it does "respect the capability of a dedicated DSP processor to offload the CPU work" for positional 3D audio calculations, although the DS3D GX engine runs entirely in software on the host system's CPU. Yet the company suggests hardware acceleration is increasingly less necessary given the power of today's processors: "we believe performance differences will continue to diminish based on the power of today's popular CPUs."
Asus also believes its DS3D GX approach to what is effectively unauthorized EAX emulation is a superior solution for those looking to enjoy DirectSound 3D and EAX effects in games running under Windows Vista. Vista's new Universal Audio Architecture strips the hardware abstraction layer for DirectSound, effectively limiting hardware-accelerated 3D audio to games that support third-party APIs like OpenAL. Creative's solution is an ALchemy software package that serves as a DirectSound wrapper, converting DirectSound calls for EAX to OpenAL. Alchemy is a standalone application, though, and it must be specifically configured to work with games installed on a user's system. DS3D GX provides similar functionality, but since it resides in the Xonar driver, there's no need for additional software or game-specific configuration.
So we have Asus, which is the world's largest PC component maker and a new entrant in the sound card market, locked in a war of words with Creative, the most dominant player the PC audio business. Creative says Asus is misleading its customers by claiming to support EAX 5.0. Asus admits that its implementation won't exactly reproduce EAX 5.0, but the company says DS3D GX produces "comparable" effects—comparable, but perhaps not genuine. The question is whether there's really much difference between the two, and it's one we'll answer soon with a full review of the Xonar DX, which I happen to have sitting right next to me. Stay tuned.