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Clean up an audio track

Posted on 2003-12-01
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Last Modified: 2008-03-04
I have several video files.  I have two seperate problems.
1.  Some files are outdoors and wind on the microphone is loud and the people are far enough away that it is a little hard to hear them.
2.  Some files are indoors and it is a little hard to hear people speaking on a stage plus the video is shot from the audience (front row) and there is frequent applause that is too loud.

I don't feel that I can just jack up the audio level because it would make the wind and applause louder.

Is there some software out there that would help with these problems?  Ideally it would be something that would automatically adjust the audio levels.

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Question by:lpenrod
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by:☠ MASQ ☠
☠ MASQ ☠ earned 63 total points
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I have to say at the outset that you may not get what you want from this.  As you've already pointed out as you boost the sound you boost all the noises you don't want as well.  Suggest you try using a graphic equalizer program (eg: http://www.versiontracker.com/dyn/moreinfo/win/12045) in the first instance to see if you can get any improvement at all.

Sadly even if you can isolate the noises you want as you increase the volume/amplitude the lack of quality in the original recording is going to become all too apparent.

M :o)
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by:lpenrod
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I didn't know if there was something that could "normalize" the audio.

I don't know much about editing audio, but in my mind I picture something that suppresses any audio above a paticular level.
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by:☠ MASQ ☠
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the graphic equalizer can reduce noises in set frequency ranges (typically the kind of white noise hiss you get when recording vinyl LPs) and can also boost ranges such as speech. They often have a "clipping" feature (which I think is what you're asking about here) where if the volume exceeds a pre-set peak it is cut down.

Is this what you are looking for?
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by:lpenrod
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Yes, that sounds like what I need.

There is not any constant noise, it is just an occasional wind gust and applause that is really loud.
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by:☠ MASQ ☠
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Wind noise can often be effectively removed using a "high pass filter". For video editing I use Adobe Premiere but there are shareware packages that will do this. A quick Google found about half a dozen. Applause may be more difficult & you may need to manually adjust the sections containing the unwanted noise.

Hope this helps

Come back with any more questions

M :o)
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by:lpenrod
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I have Adobe Premiere.  I will look in the product help for details.
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by:c_swanky
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Anything that cancels out a sound(s) will not be cheap or easily achieved without a lot of work.  I've already tired.... I played around with the eq settings and levels just like MASQUERAID suggested to no avail.

6 -7 months ago when I was researching a solution for a similar problem I found "Sonic Foundry's Noise Reduction 2.0" plugin for their 6.0 product (removes background noise)  http://www.amazon.com/exec/obidos/ASIN/b000042ol0/acoustivibratiww/102-9846191-4837714

Now they have a new version out (v7), which may include the plugin? Check it out.
http://mediasoftware.sonypictures.com/Products/ShowProduct.asp?PID=668
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Sohel Rana earned 63 total points
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Hi:

This software has feature to solve your problem:

http://www.adobe.com/products/audition/main.html

Rana

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by:c_swanky
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@lpenrod - Any luck finding what you need?  If you already haven't discovered www.dv.com, check them out. They are packed full of video equipment and editing information.

Here is a FAQ on Adobe's "Audition" ( as suggested by @rsd) that will allow you to remove vocals from a track (similar to what you're trying to do except the sound is not vocal, so it still can be applied to your use)

http://www.adobeforums.com/cgi-bin/webx?13@250.KY1kb1L5Jae.3@.2cccbe9d/0

If you have a problem getting directly to the link go here:
1) http://www.adobe.com/support/forums/main.html
2) Click on the "Adobe Audition" link
3) Click the "Adobe Audition" link again
4) Then the "Hop to Frequently Asked Questions (FAQ) folder" link
5) Look for the FAQ "MD's Tips: Removing Vocals"


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by:lpenrod
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Thanks for your help.  I am waiting for the Audition software.  Will let you know.

Thanks!
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by:eman_b
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OK lots been said here already....here's my 2 bits

Firstly, if i understand correctly, the problem is that u have recorded live audio which has a lot of background noise including wind noise and ambient noise which masks the actually desired sound.

Right at the outset, let me make it very clear that since the sound has already been recorded badly, it will be almost impossible to get it upto any decent broadcast standard, the best that can be achieved is a fair level of intelligibility in the sound, which I guess is what u r looking for.

No normalisation will not help at all....normalisation merely ...well....normalises the audio levels to near 0dB ie the amplitude (Loudness if u must) whereas it does not do much for the frequency range(clarity, if u must)

AS has been said earlier by others, there are no easy solutions for sorting out your problem.  

I swear by a nifty little programme called Sound Forge (I saw sonic foundry mentioned elsewhere in the comments)  Though its not cheap, it really works.There are several steps u need to take in order to get the sound to an acceptable level of intelligibility. We will tackle your problems one by one (viz., wind, applause)

Wind:

LPF: Use a low pass filter to cut down frequencies below 80Hz, this should significantly reduce the wind sound also it will reduce the "pop" in the voice occuring due to breathing noisily to close to the mic.

Graphic EQ/Parametric EQ: most of the human voice is in the frequency range between 150Hz and 8KHz (most speech anyways) so u might want to attenuate (cut) the frequencies above and below this range.  Dont be afraid to experiment, see what sounds best. (technically this is a band pass filter)

Applause:
As far as applause goes, I really hope that your recodring is in stereo, because then what u can do is use the inverse of the difference channel to isolate the voice and cut applause.  (Sorry for the tech jargon....read on, Ive explained it) Somtimes stereo recording mics are available in recordng devices(in camcorders, casette recorders etc, there are sometimes 2 mics in one casing giving a stereo recording on the tape)  

How this works is that normaly you would point the centre of the recording device to the source of the recording ( ie point the camcorder to the person speaking) .  Now the intersting thing that happens is that the person speaking will be picked up by both mics and recorded on both Left and Right channels equally.  The applause, murmur etc, will be recorded differently on the L and R channels. Applause of the ppl to the left of the camcorder will be on the left channel and right on right channel.  So you can keep the common data on both the channels (ie the speech) and cut out data which is different in both channels (applause).  

Use the difference plugin in Sound Forge (bundled i think)

Thanks and sorry for the tech jargon








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by:turn123
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lpenrod,
No comment has been added lately (38 days), so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area for this question:

RECOMMENDATION: split points between MASQUERAID http:#9852316 and c_swanky http:#9855460 and rsdn http:#9860894 and eman_b http:#9951302

Please leave any comments here within 7 days.

-- Please DO NOT accept this comment as an answer ! --

Thanks,

turn123
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by:lpenrod
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Sorry, I got moved to some other projects and have not had time to work on this.  I am not sure what my final solution is.  I am taking them all into consideration.  I will split the points as suggested.
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