3DsoundSurge FAQ: Aureal on Official A3D Cards vs Emulators


	Does your card officially support A3D? Does it matter? Read on to hear what Aureal has to say about on official vs emulating A3D support.

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FAQ: Aureal Explains The diffrence between A3D Cards

Skip From Aureal sent us a short technical email intended for beginners who are having trouble understanding what vortex, dsp, etc... do for a soundcard

There are 4 main types of A3D cards: Non-certified Emulators, DSP solutions, Vortex 1 and Vortex 2.

The emulators are based on various different designs. These cards attempt to capture A3D calls and render them in DS3D using a fake A3D.DLL file. Some of these calls that they try and capture are specific to A3D and cannot be "translated" into a DS3D equivalent call, and are thus ignored or handled in some other unpredictable way. Many A3D games will not function
properly through emulation and some, like Descent: FreeSpace, won't work at all.

The first of the A3D-certified cards are the DSP-based products like the Diamond Monster Sound, the Xitel Storm 3D, and the Shark Predator 3D. These cards use a generic programmable DSP (from Analog Devices or Oak) to load the licensed A3D algorithm onto the chip and process the A3D calls on the chip. Because of the generic design of the programmable DSP, there is some small bit of overhead involved to process the A3D streams, but in genreal, these cards are what you would call "an A3D hardware accelerator," because most of the processing is done on the DSP and not the CPU. Each of these cards have different characteristics in terms of number of A3D sources and 2D DirectSound sources. In the case of the Monster Sound card,
they can do 23 DirectSound sources in hardware if no A3D sources are used. If you use all 8 A3D sources (at 16bit 22K) you cannot do any 2D sources (in essence it takes up 3 2D streams for each 3D stream). If you do only 6 3D streams, you may be able to process several 2D streams as well. In the case of the Xitel Storm 3D, its DSP is a bit different and can process a
different number of 2D and 3D streams simultaneously; same goes for the Shark Predator 3D. The number of sources and the amount of acceleration depends on the capabilities of the DSP.

Next is the Vortex 1 chip. It can process up to 8 3D streams and 8 2D streams simultaneously, or 48 2D streams if no 3D streams are in use. The Vortex 1 is not a generic DSP and uses some CPU cycles to render A3D, but does hardware accelerate 2D streams. Vortex 1 chips provide better all-around features and performance, but were not designed with a programmable DSP area to run A3D in hardware.

Vortex 2 is the latest A3D platform, and is by far and away the best. Vortex 2 was designed as the ultimate, no-excuses, PCI audio processor. It not only builds on the great design of Vortex 1 in terms of DirectSound acceleration, MIDI, DOS support, joystick acceleration, etc., but it was also built from the ground up as the ultimate A3D accelerator. Gone is the generic programmable DSP area, and introduced is the specifically designed A3D hardware silicon blocks. A3D does not run in a small, software-programmable area on the chip; it runs in discrete hardware blocks on the chip to give the fastest, most-efficient and high-quality processing of the A3D effect and A3D calls possible. It also introduces new hardware blocks dedicated to the Aureal Wavetracing features.

With the very complex processing needs of 3D audio, and especially Aureal Wavetracing, we can no longer pack all of this compute-power into a generic programmable DSP (if we tried to, you'd only be able to run A3D and nothing else; no MIDI, no joystick, no nothing), so we set out to design specific silicon blocks in the Vortex 2 to handle these tasks. Gone are the
inefficient routines necessary to program the DSP, process the A3D and DS3D API calls, and apply the HRTFs and CrossTalk Cancellers. Gone are the non-concurrent solutions inherent in the Analog Devices and other DSPs:

Vortex 2 allows you to run at maximum A3D potential without affecting other parts of the chip (like 2D hardware acceleration). Now you can run 16 hardware accelerated A3D or DS3D streams and still get 80 hardware accelerated DirectSound 2D streams. The only limitation is the number of DMA channels allocated to output on the card (96). As long as you are
processing 96 or less streams of audio (be it MIDI, 2D, or 3D) it will all be done in hardware with no hit on your CPU. Imagine 16 A3D sounds, 48 2D sounds, and 32 MIDI voices all with no cost to your CPU. Or imagine 16 A3D sounds, 16 2D sounds, and 64 MIDI voices all in hardware; if you can keep track of that many sounds, I'd be very impressed.