Erik Altman photoPerry S. Cheng photo

Harmonicon - overview

Because of the ability of the human ear to detect latencies of a few milliseconds and jitter on an even shorter time scale, music synthesis provides one of the most demanding testbeds for real-time systems. Harmonicon is a MIDI synthesizer we have written entirely in Java running on top of our Metronome-based JVM.

Harmonicon implements synthesis of most of the Soundfont2 specification, and can produce high-quality piano sound.

Harmonicon is able to provide response within 1 ms of that achievable with a dedicated hardware synthesizer. We achieved 5.7ms worst-case keyboard-to-speaker latencies, comparable to a Kurzweil K2000R synthesizer.

Harmonicon demonstration comparing sound quality running on a standard Java Virtual Machine versus IBM's Metronome-enabled WebSphere Real Time product.

Continuing experiments involve the use of our Expedited Real-time Threads (XRTs) to perform CD-quality waveform generation at 44.1 KHz. Currently we are able to achieve 22.05 KHz real-time waveform synthesis.