Virtual mixer harnesses DSP

How's it work?
Software for virtual mixers, such as DigiDesign's ProTools, have required a high-end computer to make them work, since the computer's processor has to emulate analog functions at very high speeds in order to provide studio quality audio effects. However, offloading those functions into the Sharc-based PCI Express card, relieves the PC of responsibility for those tasks, enabling even garden-variety PCs to provide studio quality audio effects.

Universal Audio's PCI Express implementation realizes its goal by mediating between the virtual-mixer software and the DSPs, shuttling audio sample inputs from external devices into the Sharc, then back out to the audio outputs, using the PCI bus to accomplish all the input/output (I/O).

"All of our effects accelerators use Analog Devices' Sharc floating-point digital signal processor [DSP] on a PCI Express card that is tied together with a Xilinx FPGA [field programmable gate array] providing all the glue logic between the bus and the Sharc," saide Elder. Universal Audio's Sharc-based PCI Express cards support sample rates up to 192 KHz, and are fast enough to emulate up 128 entire audio channels per Sharc--including volume, equalization, reverb and effects. PCI Express cards are offered with one-, two- or four-Sharcs, for up to 512 simultaneously real-time tracks.