Although MIDI is often used for computer-based interactive music applications, its real-time performance is difficult to generally quantify because of its dependence on the characteristics of the given application and the system on which it is running. We extend existing proposals for MIDI performance benchmarking so that they are useful in more realistic interactive scenarios, including those with high MIDI traffic and heavy CPU load. Our work has resulted in a cross-platform freely-available testing suite that requires minimal effort to use. We use this suite to survey the interactive performance of several commonly-used computer/MIDI setups, and extend the typical data analysis with an in-depth discussion of the benefits and downsides of various performance metrics. 1

Real-time interactive software can be difficult to construct and debug. Aura is a software platform to facilitate highly interactive systems that combine audio signal processing, sophisticated control, sensors, computer animation, video processing, and graphical user interfaces. Moreover, Aura is open-ended, allowing diverse software components to be interconnected in a real-time framework. A recent assessment of Aura has motivated a redesign of the communication system to support remote procedure call. In addition, the audio signal processing framework has been altered to reduce programming errors. The motivation behind these changes is discussed, and measurements of run-time performance offer some general insights for system designers.

Digital video offers an interesting source of control information for musical applications. A novel synthesis technique is introduced where digital video controls sound spectra in real time. Light intensity modulates the amplitudes of 32 harmonics in each of several synthesized "voices." Problems addressed include how to map from video to sound, dealing with global variations in light level, dealing with low frame rates of video relative to high sample rates of audio, and overall system implementation. In one application, images of light reflected from a shallow pool of water are used to control sound, offering a rich tactile interface to sound synthesis.