so what's a zerocrossing?

People always ask me what my username—zerocrossing—means. I'm acquainted with it as a term used in digital audio to indicate the place where the signal - the sound wave - crosses the baseline.

Here's a photo from a sound file:




Now, if we expand the view horizontally, we end up with something that looks like this:




See the horizontal line being crossed by the squiggly lines? That's the baseline. The squiggly lines are the left and right stereo fields of the soundwave. The gray vertical line is where the soundwave crosses the baseline in both the left and right fields. That's a zerocrossing.

A zerocrossing is silence - though the silence is usually too brief to hear. But because it is silence, it's the best place to cut if you want to make a seamless edit to an audio file. If you cut when the wave is not at a point of silence, you usually end up with crackles and pops in your audio.

The baseline of silence is the best position from which to learn.