There is a certain delay between the program plays a sound and the sound is actually performed by the hardware. This delay may be important for Synchro Playback or for Bar Tapping.
Calibrate Device Latency dialogs helps to determine the delay when a sound event is actually heard after playing it so that WIDI could compensate for it. You may calibrate both WAVE and MIDI latency separately.
The Calibrate Device Latency dialog is brought up by pressing Calibrate... button (for Wave or MIDI Latency) on the Playback tab of the General Options dialog.
After pressing Start you will hear the clicks. Tap each time you hear the click. The process takes about 20 seconds. You may stop it by pressing Stop. After tapping, press OK button to use the displayed latency value. Calculated value will be OK even if you miss a pair of clicks.