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Old June 7th, 2007, 07:32 PM   #1
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Fixing Audio Distortion

My actor yelled a line, and I think the fact the boom was so close and the environment was a confined interior caused pretty poor distorted audio. I obviously should have done it outside or made sure the boom wasn't so close... something, because it sounds like he's blowing the mic or something. I turned down the levels so the levels themselves are not clipping, but something definitely went wrong. Any idea of any filters or anything that could potentially make it sound better? I realize this is a little hopeless, but my actor is being a prick and won't re-record despite being paid a fair amount so I'm just trying to find an alternative. Thanks.
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Old June 7th, 2007, 07:56 PM   #2
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Take a look at the raw waveform, before you adjust the levels.

If the levels go all the way to the top, (and tend to stay there during the distored passage) then you have a serious problem.

Sony's Noise Reduction 2.0 has some tools such as Clipped Audio Restoration. This can help in certain cases, but not all. This tool can be used in Sound Forge or Sony Vegas.

Is the actor available to re-record the line?

Sony's Noise Reduction 2.0 is very good. I was suprised to recently learn that it is now included in the price of Sound Forge.

Send me a private email and I will respond tomorrow.
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Old June 7th, 2007, 10:16 PM   #3
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I'm facing similiar problems (with a band being recorded) and the audio is completley distorted at the loud parts. Desperately need some way to "fix" the audio in post. I will try out the Sony Noise Reduction if I can get my hands on it. Any other suggestions?
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Old June 7th, 2007, 11:06 PM   #4
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There is no software fix for distorted audio. An occasional clipped peak may be improved, but if your audio is 'completly distorted' you really only have two options. Live with it or replace it.
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Old June 8th, 2007, 12:59 AM   #5
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Tell your actor you'll get someone else to revoice the line with the video of him doing it, that should get him to come around.
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Old June 8th, 2007, 09:56 AM   #6
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Originally Posted by Glenn Davidson View Post
There is no software fix for distorted audio. An occasional clipped peak may be improved, but if your audio is 'completly distorted' you really only have two options. Live with it or replace it.
That's right. Clipped audio is like a painting or picture where half of it was cut off. No algorithm can reproduce the missing piece from the information that is still left. If you look at clipped audio in a waveform editor, you'll see the analogy.

- Martin
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Old June 8th, 2007, 10:47 AM   #7
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Originally Posted by Dan Keaton View Post
...
Sony's Noise Reduction 2.0 is very good. I was suprised to recently learn that it is now included in the price of Sound Forge.
....
Sound Forge 9 gives you a whale of a bang for the buck, especially now that they've included both the full Noise Reduction 2.0 AND the Izotope Mastering tools in the base price. NR by itself is almost the same price as the full SF package. That's a lot of value!
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Old June 8th, 2007, 02:07 PM   #8
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Well, of course there is no way to completley fix distorted audio, but I'm interested in the part where you mentioned improving the occasional clipped audio.
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Old June 8th, 2007, 04:44 PM   #9
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As others have noted, this is certainly a bummer situation, as is always the case with severe distortion in important audio.

Audio noise is not the same thing as audio distortion, and there are a number of applications that can help reduce or eliminate audio noise. But in terms of distorted audio, it is rarely worth the effort as there is really no way to make it sound NOT distorted. The best that can be hoped for is to shave away some of the frequencies that comprise the distortion to perhaps make it less instusive...but its still gonna sound like distorted audio.

-Jon
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Old June 8th, 2007, 09:39 PM   #10
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Will, can you post a short clip up? (Even mp3 would be fine.)
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Old June 9th, 2007, 08:29 AM   #11
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One of our camera operators, while filming an important live action scene, set the levels wrong and did not monitor his audio.

About 50% of the audio was clipped.

I used Sony's Noise Reduction 2.0 "Clipped Peak Restoration" successfully to restore the audio.

In other cases, usually when a substantial portion of the audio is clipped, it did not achive the results I needed. But this is to be expected.

Once audio is clipped (more that just occassional clipping) one is lucky to be able to salvage the audio.

If you have just an occassional clipped peak, the Sony's NR 2.0 tools can be very useful. Generally in depends on the nature of the audio.

The three other tools in Sony's NR 2.0 are also very useful.

Some of these tools are very easy to use.

I highly recommend having this tool available.

If you purchase Sound Forge 9, the tools are now included in the package, which cost less than what I paid for the NR 2.0 tools by themselves.

In one case, for unknown reasons, we had some variable high-pitched squeals in some dialog. I do not remember exactly which tool I used, but I was editing with Vegas with NR 2.0, and I was able to extract great audio from the mess!
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Old June 11th, 2007, 08:26 PM   #12
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My Canon XH A1's meters don't always tell the whole story. (note to self: always use headphones...) I recorded a live band at an event by watching my VU meters (am I giving away my age?) The audio was clipped and I normally would have tossed the footage but thought I would see what was available in my "new" version of Adobe Audition. (I've used it since it was Syntrillium's Cool Edit '95) It now includes a Clip Restoration function that provides a few "dials and buttons" in order to adjust the parameters such as input attenuation and overhead. It saved my music clip. If you can't re-shoot (as was my case), it's worth a try.
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Old June 14th, 2007, 04:48 PM   #13
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Originally Posted by Alex Thames View Post
Well, of course there is no way to completley fix distorted audio, but I'm interested in the part where you mentioned improving the occasional clipped audio.
The best way to "fix" it is to use a good mixer with a limiter so it doesn't clip in the first place.

The Sound Devices 302 and 442 mixers are virtually uncrashable except when operated improperly.

Regards,

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Old June 14th, 2007, 05:36 PM   #14
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Yes, but that is besides the problem. That is preventing it from happening in the first place. And of course we would all prefer to have prevented it, but that isn't the reality now and we can't go back and change the past. In the future, more care will be taken, but for audio that is already recorded badly and can't be re-recorded.

Last edited by Douglas Spotted Eagle; June 15th, 2007 at 11:09 AM. Reason: inflammatory comment
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Old June 14th, 2007, 08:31 PM   #15
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Apparently there are some decent fixes according to the info given here in this thread, which I'm going to try out. Of course there is no perfect fix that'll make bad audio sound as good as if the audio had been recorded well. That much is obvious. But tips on improving bad audio are always appreciated. And that is the point of these threads/questions.

Being a "major player" means absolutely nothing. I don't care about about these sort of "for fun" ranking systems. It doesn't imply one who is of a different rank is better or more knowledgeable. The only true thing it means is how many posts you have made.

The answer to "How do I fix bad audio?" is never "Just don't record bad audio to begin with." That is pretty much a useless answer analogous to answering the question "Help! I'm pregnant" with "So just don't get pregnant" or answering the problem "I ran out of gas in my car and now I'm stranded in the middle of nowhere! Help!" with "So just don't run out of gas next time. Make sure you watch your gas tank and fill up before it's too late." Not a lot of good that will do after the fact, after the damage has been done already.

No one is disparaging you from your intentions to educate people on how to record good audio to begin with. Those tips are helpful on their own and are appreciated, but it doesn't help in the context of the question of how to improve bad audio. That's all my point is.
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