Looping *pop* / *click*

[Darkness_Falls]

I know some of my machine-hum type submissions are large file sizes. They could easily be made much smaller (if someone hasn't done this already) by making it a shorter audio piece. Whenever I've tried to finish a sound so that it loops nicely with the beginning, however, it's often not a smooth transition from the end of the file to the start of the file. Is there a secret to smooth looping? For instance, is there a setting or filter in most audio programs that I'm not familiar with that would successfully transition/merge the end with the start to make it smooth? Next time I'm in my audio program, I might try copying the beginning and doing a "mix paste" to the end to see if that works, but I have my doubts that it'll work, due to how wavelenghts are structured (amplitudes/interference and all).

 

I was just hoping there was a button I could click and the audio program would know what I was wanting to achieve and do it for me. It seems this would be such a common things for sound engineers to want to do, so thought there *must* be a button or menu item somewhere that I'm just not aware of.

[Domarius]

Well if you're talking about the pop/click noise, yes there is a secret.

 

If you zoom right in on the waveform where the sound ends and then restarts (well to see this you're going to have to paste the same file end to end), you'll see that the wave form won't match. It will be smooth and wavey, then it will cut abruptly and start at a different position when the next pasted sound starts.

 

You need to trim the end off of one of them until the waveform meets and forms a continuous line. That will remove the pop/click.

 

As for making the sound sound continuous, well, an old trick I used to do is just crossfade one into the other. Fade out one end, fade in the other end, then do a paste&merge so that both fades overlap (creating a crossfade). While very cheap and nasty, it works for lots of ambient sounds. If it doesn't work for you, one of the sound guys should have some more advice.

[Darkness_Falls]

Ahh, thanks Domarius! I'll give them a shot. I had tried the first thing before, but I never zoomed in far enough to see the continuous line before; so that makes sense and I will try it. As for the 2nd one, I will give that a shot first since that's probably the easier of the two. Thanks again!

[Domarius]

You still have to make the waveforms meet before you do anything else! Otherwise no matter what effect you use (crosffade or whatever) to blend them together, there will always be a popping noise.

[saxmeister]

Dom is totally right. The waveforms need to meet. This can be done via the crossfading or can be done manually in most sound editors by "drawing" the wave with the pencil tool. If you zoom in (a lot!) you can see the waveform and where it ends. TIP: Try making one side of your waveform start by going up from 0db and then making the other end go up to 0db.

 

This is especially important when working with stereo files since there are hardly ever any instances where the left AND right channels hit 0db at the same time.

 

Then you can try it as is or use the crossfade......

 

I hope this helps!

 

-sax

[Darkness_Falls]

Definitely. Thanks guys! I'll give it a try the next time I delve into the sound realm.

[Domarius]

All sound apps have tools for dealing with this, one way or another. In CoolEdit Pro, there are zoom buttons that zoom in to the left or right edge of a selection. So you can zoom in right down staying centered on one of the edges - useful if you try to make a loop by cutting the end half and pasting it before the first half - the half that you pasted is still selected, so zoom right in on the right end of the selection, and make the waveforms meet.

[Schatten]

Yup, what Dom & Sax said.

 

Also, effects that will make looping more tricky are verb and phaser/chorus/flaser. Dealing with verb can be managed, but when it comes to phasers making a sound loop seamless is VERY hard, because of the problem Sax mentioned.

 

If you have sharp clicking sounds, like a hat or a snare, you may try to loop at this point because the high frequencies can hide some of the popping.

 

If the solution of trying to manage a 0dB start and end of the waveform is not an option (or will produce a pop itself, as it happens), I always employ a technique I learned from creating seamless textures:

I cut the waveform in half, reverse the order of both pieces, and mend them together in the middle. This way you can see the parts left and right of the cutting point and mend it according to the "flow" of the waveform.

 

But while we're on topic, has anybody figured out a good way to deal with phased sounds? For the larger part of the ambients I created so far, I tried to mimick the effect with frequency splitting and other static mono-to-stereo gizmos, but I begin missing ye' olde phaser swirl.