Netmix Audio is a programming framework that contains a set of tools being developed in conjunction with live performance with the capability of distributed realtime DSP operations on sounds. MIDI control signals are broadcast to an ‘orchestra’ of PCs on a network which synthesize and process sounds. This affords DSP capabilities limited only by the number and power of the PCs, and in particular, gives the capability for spatialization of sound with large numbers of outputs, and for non-local performance.

Introduction

The Netmix Audio project is a system that was designed for a specific performance, but which we feel has wider implications and possibilities. Our basic intent was to synchronize multiple computers for realtime sound processing. We began without a particular DSP scheme in mind, but thought it would be a good idea to use multiple computers so that we could avoid running out of processor power, as we inevitably did when using a single computer. We very soon arrived at the notion of using oscillator banks to resynthesize frames of FFT analysis data, noting that oscillator banks lend themselves especially well to parallel processing.

Consideration of Other DSP Systems

The decision to design our own system was taken after experience with several realtime and non-realtime audio DSP systems. The non-realtime systems (particularly Csound and CMIX) are of interest mainly in that they provide a benchmark for programming ease – a way of measuring the added complications that arise in dealing with realtime programming. The two realtime systems which we explored were Kyma and PD. Kyma, was and remains a tremendously powerful system – probably still the most powerful DSP system at its price point. We had used the Kyma system successfully in prior performances. However, since Kyma opcodes must be written in assembly language, and we did not believe we could easily write our algorithms using the (many) available Kyma opcodes, we had to look elsewhere. Miller Puckette’s PD (Puckette 1996) had recently been released, and looked most interesting. It was clear that we could accomplish what we wanted in PD, since it is