2 - Master Menu

Miscellaneous

Zero Crossing Threshold

Background

The term “zero crossing” refers to the point at which the positive slope of a waveform passes through zero. In many sample editing applications, such as splicing and looping, it is useful to locate zero crossings in order to make glitch-free joins and loops. On some signals, however, a simple zero crossing may not be effective because the signal contains excessive noise or low-level, high-frequency harmonics. In these cases, every few samples may cross through zero. By setting a zero crossing threshold, we can ignore lowlevel zero crossings and wait for the signal to reach a certain level before choosing the next zero-crossing. Zero crossing threshold sets a level that a signal must exceed before the next zero crossing with a positive slope is selected. The defined zero crossing threshold is used in the Auto-Truncate function or whenever you manually select a zero crossing using the cursor buttons.

The following diagram illustrates zero crossing in action. The small x marks the initial position.

Zero X Threshold
	(Set at -30 dB)	Slope of
		Wave
Ignored		+ -
-30dB
-96dB
Selected
Slope of
Wave
+	-	Ignored
-30dB
-96dB
	Selected

To move forward through the sound to the next zero crossing, press the right cursor button, as shown in the previous diagram. EOS finds the first zero crossing on the positive slope after the signal has crossed the threshold.

To move backward through the sound to the next zero crossing, press the left cursor button. EOS finds the first zero crossing on the positive slope after the signal has crossed the designated threshold.

88 E-MU Systems