Audacity Forum

Koz, intrigued by the notion that one must do an edit at a "zero crossing point." I assume this is where the waveform approaches 0 db - right?

How then does one do an edit if there is significant background noise (like the government truck I conducted the interview with Joseph Nyabire?

<<<I assume this is where the waveform approaches 0 db - right?>>>

You ready to go screaming into the night?

No. It's where it hits zero volts. And it hits zero volts at infinity dB. We use a value system where "Zero dB" is as loud as the system gets. It's more accurately 0dBFS; zero dB Full Scale. As loud as it gets without distorting. The highest audio voltage you can generate before it starts a small but entertaining fire.

http://www.kozco.com/audacity/CEdit.jpg

Make the screen as large as you can. Its a pretty big photo.

That's a screen capture of Another Audio Program with the dB values marked with a ruler. That's what's really there. The Audacity timeline graphics are an approximation. The pretty graphics are one of the things you can get when you part with the Benjamins.

Anyway, When the dB values are as high as they can get, then the volts in the electrical signal are as low as they can get, then that's a grand place to do a noise-free edit. The idea is important enough to be marked in that picture with a red line. Where the green waveform crosses the red line--anywhere they cross--is the place to put the razor blade.

If both of your edits are on the zero volt crossing points (infinity on the graph) then there is no electrical difference when the system travels from one tune to the next at the cut. No pop or click. You can still get into trouble by doing that, but the possibilities of audible garbage go way, way down.

None of this makes any difference because to actually edit on the zero volt crossings is really difficult in most audio programs. They won't let you select and zoom at the same time--or not easily. I figured out a way to do it once in my Other Audio Program by reprogramming Hot Keys, but it was just so difficult I gave up and went back to doing four or five rough edits to get one really good one.

Koz

Oh, yes. The question. It doesn't matter what the sound is, they all cross zero volts/infinity dB. Metro Bus, United Airliner, doesn't matter. If you can hear it, it's going to cross that red line. The easiest way to find that in Audacity is use the non-dB marked timeline, pull the picture as tall as you can, and use a grease pencil to draw the "0.0" mark across the screen.

On my screen capture, you're suppose to notice that the particular show is in full stereo which means that the left and right don't match.

Yes. That's correct.

Koz

Simanza, don't worry about the zero crossing point if either the Repair or Fade In/Out techniques work.

Basically, he's saying you should zoom way in on the point you want to make an edit and cut at a point where the waveform crosses the (horizontal) center line. To my knowledge, Audacity doesn't really offer an easy way to do this, and the Repair and Fade in/out techniques are both valid workarounds. There's no reason to do this the hard way if there are two equally workable "easy" ways.

Koz, you seem to have gone eccentric overnight. Your information is correct but a bit difficult to follow, I think.

Hopefully this will be easier to read:

0dB is the reference point for highest volume, this is not the same as the "zero line". The zero line is actually at -96dB for 16-bit values. The different bit depths each have a different "lowest volume" but the same "highest volume," this is why the reference is at zero. It makes more sense that way from a math or engineering perspective.

0dB on the vertical scale (all the way at the left edge of each clip) is actually listed at +1 and/or -1.

Bonus trivia: You can get an extra 6dB of resolution out of a signal for every bit you use.

A bonus, bonus is that I rough-cut edit three hour-long radio shows every week. I don't pay the slightest attention to the zero crossings and I don't get pops. So it's my clever way to avoid addressing the original problem.

Yours in obscurity.

Koz

Haha, I think I have a new motto now:

When in doubt, obfuscate.

OK, thanks very much. But here's the thing: I am still getting these clicks at each edit point. These clicks do not show up on the waveform - not even when I zoom in to the finest detail. They are somewhat more obtrusive when I use the <delete> key instead of ctrl-x. But they are still there.

I have saved and closed the project and re-opened it to see if the clicks are an artifact of having the project unsaved; they remain.

I have exported the project both as .wav and .mp3 files and then opened the project in another computer; same thing.

I tried opening it in 1.3 - clicks are still there. I'd love to share you a section but the forum will not allow me to upload either .wav or mp3 files.

Any suggestions?

Simanza

Now you have two postings like this and I responded to the other one.

Koz