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How to minimalise audio 'spikes'

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Olly Lawer
How to minimalise audio 'spikes'
on Mar 16, 2011 at 8:08:19 pm

Hi,

Used a G2 mic for a live recording. Set the controls on the EX1 to auto as the person we were filming is a story teller, so very loud parts and very quiet.

The audio has come out very well, apart from 11 interference 'spikes' in the 1hr and a half footage. Literally, they are are just bits of intense interference that last no longer then a second, but are frustrating and I want to get rid of them. They are not related to loud moments in the footage or when he is moving. They are seemingly random.

Any tips would be very much appreciated.

Kind regards,

Olly Lawer


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Frank Nolan
Re: How to minimalise audio 'spikes'
on Mar 16, 2011 at 8:15:20 pm

It seems they maybe RF interference which you are pretty much stuck with. Did you have a boom recording as well that you can cut to? If not maybe somewhere else in the recording he says the same word that you could edit in place.



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Olly Lawer
Re: How to minimalise audio 'spikes'
on Mar 16, 2011 at 8:17:27 pm

Can't do either really, it wouldn't fit.

I guess this must be a common problem? G2 mics are very popular and there is no rhyme or reason for the spikes, so maybe this happens a lot?

Surely there is a way of editing out the spike? You can still hear him under the spike, so maybe adjusting the frequencies in some way?

Olly Lawer


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Eric Toline
Re: How to minimalise audio 'spikes'
on Mar 16, 2011 at 10:24:05 pm

What you experienced were RF hits. Cause usually unknown. After 1 or two hits a frequency scan on the receiver would be in order to find a clear path although that is no guarentee but it would get you off the frequency with the hits.


Eric


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Olly Lawer
Re: How to minimalise audio 'spikes'
on Mar 16, 2011 at 10:25:34 pm

Thanks, but couldn't do a frequency scan as it was a live recording.

Is there any way of getting rid of them?

Thanks

Olly Lawer


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Frank Nolan
Re: How to minimalise audio 'spikes'
on Mar 16, 2011 at 11:08:43 pm

[Olly Lawer] "Is there any way of getting rid of them?"

You can edit them out but if he is talking right where they happen then you are stuck with them. If you want to post a small file with one spike I will take a listen and see what I can do.



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Olly Lawer
Re: How to minimalise audio 'spikes'
on Mar 16, 2011 at 11:10:22 pm

Thank you. Very much appreciated. I'll do that tomorrow as it's late here.

Olly Lawer


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Peter Groom
Re: How to minimalise audio 'spikes'
on Mar 17, 2011 at 10:08:13 am

Yes post a link to a bit and well have a listen.
If theres a 1hr+ recording and only 10 or so spikes, cant you can find wthe affected words elsewhere and chop them in? You get a lot of words in an hour!
Peter

Post Production Dubbing Mixer


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Olly Lawer
Re: How to minimalise audio 'spikes'
on Mar 17, 2011 at 10:47:10 am

Possibly, but he varies his speech so often that I think it will sound odd. Can test it.

Olly Lawer


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Peter Groom
Re: How to minimalise audio 'spikes'
on Mar 17, 2011 at 11:12:10 am

Have you uploaded a file (or can you email me one as an mp3 or similar.

Peter

Post Production Dubbing Mixer


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Ty Ford
Re: How to minimalise audio 'spikes'
on Mar 17, 2011 at 1:30:18 pm

Hello Oliy and welcome to the Cow Audio Forum.

You have received good information in this thread. Since this seems to be something new for you, I will add the following. Wireless mics are more vulnerable than hardwired mics, but RF disruption can happen on hardwired mics as well. We just have too many RF-based toys.

In addition to actual noise, wireless mics may also suffer from reduced range due to interference. I try to fight that by hanging my receiver bag as close to the person wearing the transmitter as possible and cabling back to my mixer. I can usually find a light stand near the shooting area to hang the bag on, or I use one I bring with me. You want an spot that'll provide you an unobstructed "view" from the transmitter to the receiver. I usually try to get my receiver bag waist high or higher, so if someone walks or stands between the transmitter and receiver, they won't present as much of an obstruction.

Directional receiver antennae are also helpful, but require additional mounting and cables.

Regardless of what CSI may show on TV, don't expect similar results. Some noises can be reduced. Others can't. The success usually hinges on how broad spectrum the noise is. The wider the spectrum, the more difficult it is to remove the noise. By spectrum, I mean the spread of low to high frequencies. There are software and hardware filters that can pull 60 cycle hum out pretty well. HVAC noise is broader spectrum. It has noise across a wider range of audio frequencies. Pulling that noise out without compromising the voice (or whatever you're trying to record) is more difficult.

Regards,

Ty Ford

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide





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Peter Groom
Re: How to minimalise audio 'spikes'
on Mar 17, 2011 at 1:36:45 pm

Im dying to hear some audio. Just how long and big are these spikes.
Peter

Post Production Dubbing Mixer


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Peter Groom
Re: How to minimalise audio 'spikes'
on Mar 22, 2011 at 4:00:31 pm

Did you get this sorted?
Peter

Post Production Dubbing Mixer


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Olly Lawer
Re: How to minimalise audio 'spikes'
on Mar 22, 2011 at 4:06:45 pm

Sorry for not coming back sooner! Haven't had a second to breathe.

Got sorted to an OK level. Although time consuming, the very short peaks I sorted by cutting them out. You can tell it doesn't sound quite right, but is better then the sound abnormality. The smaller I could make the sound cut the better obviously.

There was one sustained interference which sounds a little unprofessional when I've cut it out.

If I get time tonight, I'll clip the before and after and post them.

Kind regards,

Olly Lawer


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Peter Groom
Re: How to minimalise audio 'spikes'
on Mar 22, 2011 at 9:47:08 pm

When you cut them out, are you using a video nle or an audio application (pro tools etc)
Peter

Post Production Dubbing Mixer


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Olly Lawer
Re: How to minimalise audio 'spikes'
on Mar 22, 2011 at 9:48:11 pm

No, literally I am zooming in on the timeline in FCP and using the pen tool.

I guess there are a LOT better ways ;/

Olly Lawer


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Peter Groom
Re: How to minimalise audio 'spikes'
on Mar 23, 2011 at 10:00:43 am

I think part of your problem there will be that video edit platforms only allow editing of + or - 1 frame, which is a very coarse amount for audio. Audio applications allow editing down to the sample, which is 1 48000th of a second for example (depending on your audio sr.) So you can see how your audio edits may well be more notiecable in an VNLE than in say Pro Tools.
Looking forward to seeing the audio clips tho??

Peter

Post Production Dubbing Mixer


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Paul Kagawa
Re: How to minimalise audio 'spikes'
on Aug 11, 2011 at 9:39:25 pm

Hi, I've been having problems with audio spikes too, from a wired mic going through a PA system, and AUX out to XLR inputs in my camera. It happened in two different instances with two different PA's. Are these the RF spikes that you are describing? Is there any way to avoid them in the future?

2784_clip1barry.wav.zip


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