The EM Poll

Sharing the Load

Apr 1, 2005 12:00 PM, By Orren Merton

           

When you see an audio plug-in running on a computer, it's natural to assume that the processing is being handled by the computer. The digital signal processing (DSP) software, however, may actually be running on a PCI card inside the computer or on an external hardware device connected to the computer by USB or FireWire. When DSP is carried out inside the computer, the processing is called native; software that uses additional hardware connected to your computer for its DSP is called hardware accelerated, and the additional hardware is called DSP-accelerator hardware. Traditionally, hardware-accelerated systems have been the realm of the high-end production studio, but today some DSP-accelerator cards are even less expensive than native plug-in bundles. In this article, I'll discuss various DSP-accelerator-hardware options and how they compare with native solutions.

Hardware-accelerated DSP offers some significant advantages, the most obvious being that it adds processing power to your computer. Arguments about whether native or hardware-based systems are more powerful miss the point; DSP hardware supplements, rather than supplants, native processing. With a Pro Tools Time Dimension Multiplexing (TDM) system, for example, you can use the DSP power of your hardware to run TDM plug-ins, and the native power of your computer to run RTAS and HTDM plug-ins. When using Universal Audio UAD-1 Powered Plug-in or TC Electronic PowerCore, you can run DSP-based and native plug-ins on your host application. You'll always get more processing power when you use a combination of hardware-accelerated and native processing.

DSP Flavors

DSP-accelerator hardware comes in a variety of flavors. PCI cards that fit inside your computer, such as the UAD-1 PCI card (see Fig. 1), the PowerCore PCI card, the Digidesign Pro Tools HD|Accel system, and the CreamWare Pulsar/Scope system are the most common. External rackmounted DSP-based hardware devices that connect to your computer via USB 2.0 or FireWire have also begun to appear. TC Electronics' PowerCore FireWire is one example.

FIG. 1: Universal Audio’s UAD-1 Powered Plug-in PCI card runs software models of classic analog hardware compressors and EQs, such as this emulation of the Fairchild 670.

There are two types of hardware-based DSP systems: self-contained systems and systems that work with a variety of native software hosts. With a self-contained system, everything related to audio processing is handled by the DSP hardware, including audio input, all signal processing and mixing, and audio output. Only the proprietary editor software runs native on the computer. The best known proprietary system is Pro Tools TDM. With a Pro Tools TDM system (there are Mix, HD, and HD|Accel versions available, each with different track counts and DSP power), the TDM hardware handles audio I/O using special TDM-only audio interfaces, mixes audio together with its 48-bit hardware mixer, and provides for effects processing using hardware-based TDM effects. The Pro Tools software serves as a native front end for the TDM hardware. Merging Technologies' Pyramix system is another self-contained audio production solution.

Nonproprietary hardware accelerators are not limited to working with a specific native-audio engine and allow you to integrate their DSP with plug-ins running natively in your chosen host software. Examples include the UAD-1 and PowerCore PCI cards. Those run proprietary plug-ins on their DSP hardware that integrate with plug-ins in formats such as VST, AU, and DirectX that are running native in your host software.