Sound editing: Getting rid of regular clicks?

September 24, 2006 11:47 PM

How do I get rid of these tiny clicks in the left channel of this audio file, every 10 seconds?

I have a live recording, made straight to CD. It's a little scratched up, and I imported it into iTunes with error correction. The mp3 has little clicks in the left channel, every 10 seconds. Questions:

1) Is this likely due to CD scratches, or something in the recording process? (Will a scratch on a CD produce this sort of 1-channel, 10-second interval, regular clicking?)
2) If so, can I get rid of it with better cleaning of the CD? (I've tried wiping it radially outward with a soft lens-cleaning cloth, with no luck)
3) If not, is there anything I can do to get rid of it without impacting the sound quality?

posted by anonymoose to computers & internet (8 comments total)

Have you tried doing it without the error correction?
posted by samstarling at 12:39 AM on September 25, 2006

I don't see how a scratch on a CD could cause that. If a scratch was going to affect anything, it would affect both tracks equally.

CDs are CLV so the rotation rate changes as the head moves, but the spin rate is on the order of 5 revolutions per second. It's hard to see how a scratch would cause a discontinuity regularly once every ten seconds (once every fifty revolutions, plus or minus) no matter what kind of effect the scratch caused on the playback.

Are you sure that click is not in the original audio that's on the CD? Have you tried playing it in a normal CD player, and listened to it with headphones?
posted by Steven C. Den Beste at 1:13 AM on September 25, 2006

If you're on Windows, give Exact Audio Copy a whirl.

As far as repairing it if the click are indeed on the CD: Most audio editors these days have some sort of click correction. The really good ones will show you where the click are (e.g. if they're every 10 seconds you know it's getting the right ones). I imagine there's some piece of freeware/demoware you could use (in Windows, I like Sound Forge, which I believe there's a demo for, but I dunno about Mac software).
posted by neckro23 at 2:28 AM on September 25, 2006

I've had good luck with Goldwave's pop/click filter to remove these types of noises.
posted by pierow at 3:41 AM on September 25, 2006

Any recommendations for mac software filters?
posted by anonymoose at 8:51 AM on September 25, 2006

I've had good luck on OS X with using iTunes with error correction enabled (which seems to smooth a lot of minor errors) to encode to iTunes LAME. It's not being updated anymore, form what I can tell, but you can easily upgrade the binary inside the script package with any Darwin binary of LAME.

Hydrogen Audio is a pretty good resource for encoding.
posted by bafflegab at 9:27 AM on September 25, 2006

I've checked the audio on another player, and the clicks are still there, so I'm assuming the audio is a part of the original recording.
posted by anonymoose at 9:58 AM on September 25, 2006

Audacity runs on the Mac and has a "Click Removal" effect. I haven't tried it myself, so I don't know how well it works.
posted by mbrubeck at 10:00 AM on September 25, 2006