What is the latency (or delay) time for callbacks from the waveOutWrite API method?

Question

I\'m having a debate with some developers on another forum about accurately generating MIDI events (Note On messages and so forth). The human ear is pretty sensitive to sli

Answer 1

The Windows scheduler runs at either 10ms or 16ms intervals by default depending on the processor. If you use the timeBeginPeriod() API you can change this interval (at a fairly significant power consumption cost).

In Windows XP and Windows 7, the wave APIs run with a latency of about 30ms, for Windows Vista the wave APIs have a latency of about 50ms. You then need to add in the audio engine latency.

Unfortunately I don't have numbers for the engine latency in one direction, but we do have some numbers regarding engine latency - we ran a test that played a tone looped back through a USB audio device and measured the round-trip latency (render to capture). On Vista the round trip latency was about 80ms with a variation of about 10ms. On Win7 the round trip latency was about 40ms with a variation of about 5ms. YMMV however since the amount of latency introduced by the audio hardware is different for each piece of hardware.

I have absolutely no idea what the latency was for the XP audio engine or the Win9x audio stack.