Quickie audio sweetening... Take the edge off this clipped audio

M

markyf

Well-known member
I recorded something for work where I had to follow a woman doing a skit around a very loud bar. I was very worried about not hearing her or the people she was interviewing and therefore was pretty lenient about letting the audio bars go into the red. I know... you sound guys are shaking your heads. I tried to ride the input knob on my DVX for awhile but it's too hard to do that and shoot.

Anyways, I've got some pretty badly clipped ugly sounding audio in parts. I don't care that it's a little clipped... It actually works with the environment. I just want to soften it some, in Final Cut Pro. Any advice?
 
Advice?........Do yourself a favor next time...Do it right.

Read the manual, use the ALC, practice, prepare ahead of time.
 
Oh lord... Knew that one was coming. Now that I've been reprimanded, what can I do know? This was a favour for work and not something I normally do. Just trying to rescue it.
 
Well… sometimes you can run the audio through a declipper many times, but that may only slightly work. I don't know if there are any tools specifically in FCP that will help.
 
Well, there's not actually much you can do about it. Not familiar with FCP's sound editing tools, and I assume that most video guys won't also have ProTools. Go get audacity from sourceforge.net (free download) and import your audio into that program. Run the normalizer effect and let it run with the default values that it will import for itself.

I'm afraid that's about all you can do to fix it. And it won't fix it, but it will minimize it. Fixing digital signal clipping is pretty much impossible. Sucks, I know... I've been there myself when a client has given me audio to work on where they clipped it in recording and I've had to just come back and say "sorry."

Good luck!
 
davbeisner said:
Well, there's not actually much you can do about it. Not familiar with FCP's sound editing tools, and I assume that most video guys won't also have ProTools. Go get audacity from sourceforge.net (free download) and import your audio into that program. Run the normalizer effect and let it run with the default values that it will import for itself.

I'm afraid that's about all you can do to fix it. And it won't fix it, but it will minimize it. Fixing digital signal clipping is pretty much impossible. Sucks, I know... I've been there myself when a client has given me audio to work on where they clipped it in recording and I've had to just come back and say "sorry."

Good luck!
Click to expand...


Normalize won't do ANYTHING to fix peaks that have been sheared off by clipping. Your only (very limited options) are to find a plugin to de-clip them or attempt to manually redraw the waveforms. I have had limited success with manual redraw to remove pops / clicks and the occasional destroyed waveform, but that is about it.
 
I didn't say it would FIX them, I said it would MINIMIZE THEIR EFFECTS. And it does. I've done it, multiple times. I've also tried re-drawing the waveform and that doesn't do much good. It's also very time consuming and if this is a pro-bono project, it's probably not something he wants to do.
 
Incidental clips and momentary snaps can be delt with by either cutting out the offending audio or redrawing the waveform, but if significant portions of the waveform are overmodulated then you're hosed.

If its as bad as your post suggests, then there's no way to fix it; the best you can hope for is to make it slightly less offensive to the ears. De-clipping plugins are worth a try, and you could also try rolling off some of the higher frequencies to take some of the bite out of it. However, the only reliable way of repairing badly distorted sound is to either re-shoot or ADR the sequence.

Try to look at the bright side: you're unlikely to loose your job over this. I bet you'll never again roll tape without using closed-back headphones, though.
 
Thanks for all the help. You guys are great. As a temporary thing, I put a low pass filter over it and just wiped out the high frequencies. Makes it somewhat more listenable. I will try normalization too and check out audacity.

Here is the clip on Vimeo (sorry if it gets hung up, not my fault):

http://vimeo.com/1223696

In the grand scheme of things, how is it as is? I've listened to it so many times I don't know anymore.
 
davbeisner said:
I didn't say it would FIX them, I said it would MINIMIZE THEIR EFFECTS. And it does. I've done it, multiple times. I've also tried re-drawing the waveform and that doesn't do much good. It's also very time consuming and if this is a pro-bono project, it's probably not something he wants to do.
Click to expand...

If it works for you, thats great, but the fact is that all normalize does is apply either a gain increase or reduction to an entire clip/track based on the highest peak. If that is what you are doing you could achieve the same result by just moving the fader.

If the issue is that the clipped portions are significantly louder than the ok material, I would suggest drawing in some volume automation on the clipped areas, or selectively applying gain to the clipped area.
 
As you can see in the video, most of the clippng is coming not from the person speaking to the camera but from general bar noise. And it is consistent. Since this is for the web and is going to be pretty lo-fi, I am not too concerned. But if I could make it 25% better, since my ears start to hurt after listening to all of it, I would be very happy. What about a compressor?
 
Compressor won't do you any good. Use keyframes to bring down the volume between the areas where your interviewee is talking and it will help minimize the effect.
 
Audacity is a great tool for doing quick and dirty edits and multi-track mixing if you can't afford something like Pro Tools. In fact, I actually use Audacity for most small projects in my studio and only go to Pro Tools when I'm doing a big multi-track project or music composition. You can draw your waveforms and draw your audio using keyframes pretty easily in Audacity. PM me if you'd like some tips on how to use it to its full capacity.
 
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