Audio and Gesture Latency Measurements on Linux and OSX

We have measured the total system latencies of MacOS 10.2.8, Red Hat Linux (2.4.25 kernel with low-latency patches), and Windows XP from stimulus in to audio out, with stimuli including analog and digital audio, and the QWERTY keyboard. We tested with a variety of audio hardware interfaces, audio drivers, buffering and related configuration settings, and scheduling modes. All measured audio latencies tracked expectedly with buffer sizes but with a consistent amount of unexplained additional latency. With analog I/O there was also a consistent additional bandwidth-dependent latency seemingly caused by hardware. Gesture tests with the QWERTY keyboard indicate discouragingly large amounts of latency and jitter, but large improvements on Linux when real-time priorities are set.