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Author Topic: [Tutorial] Removing Audio Noise Using Audacity  (Read 8895 times)

Offline Ryan

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[Tutorial] Removing Audio Noise Using Audacity
« on: January 20, 2011, 03:49:11 PM »
Hey all,

I want to see if I can further clean up the audio (after disabling AGC using Magic Lantern) by using Audacity's Noise Removal filter.  It's worked awesome in the past with other stuff I've done (non-t2i related).  Can anyone suggest a workflow or a way of extracting audio from a t2i .mov clip without affecting its quality so that I can do this?

My google-fu is weak today.
« Last Edit: January 30, 2011, 07:25:04 PM by Ryan »
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Offline Ryan

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Removing Audio Noise Using Audacity
« Reply #1 on: January 20, 2011, 04:58:01 PM »
Okay, I may have gotten somewhere.  I think I came up with something half decent...

Please note that I'm running Windows 7 64bit.  I'm not sure if the instructions below will work on other operating systems.

INSTALLATION

1.  Download and run the latest Audacity 1.3.12 installer

2.  Download and run the FFmpeg Installer (required to import the t2i .mov files into Audacity)

3.  Open Audacity -> Edit -> Preferences -> Libraries

4.  Click on the 'Locate...' button next to 'FFmpeg Library:'

5.  There should be a message that says, "Audacity has automatically detected valid FFmpeg libraries.  Do you still want to locate them manually?"  Click 'No'

6.  Click 'OK' on the Preferences Screen

IMPORT AUDIO FROM CLIP

7.  Click File -> Import -> Audio...

8.  Choose your t2i .mov file and click 'Open'

FIX MONO AUDIO SOURCES

9.  If you're not using a mono lav mic (ex. ATR-3350) like I am skip to step #12, otherwise you'll notice that the audio was captured in the left channel and nothing was capture in the right channel.



10.  Press the down arrow on the top left of the clip and click on 'Split Stereo to Mono'



11.  You'll now have two separate audio streams, you can delete the second one (the one underneath) and you'll noticed that the one on top that remains has converted the mono sound to stereo.



REMOVE AUDIO NOISE

12.  Now for the fun part, highlight a quiet section of audio (preferably 1 second), then go to Effect -> Noise Removal...



13.  Now click the 'Get Noise Profile' button.  What this does is capture the noise profile of the selected portion of the clip that we highlighted in the previous step.  The Noise Removal window will disappear, this is normal.



14.  Now double-click your clip so that the whole thing is highlighted.  Go back to Effect -> Noise Removal..., then simply click 'OK'.  This will remove the noise profile previously captured from the whole clip.

EXPORT NEW AUDIO FILE

15.  Click File -> Export... and choose 'WAV (Microsoft) signed 16 PCM' as the 'Save as type:'

16.  Choose a name for the new audio clip and click 'Save'

Once you've created your new audio clip, you'll want to import it into whatever editing program your using, place it on an audio track below the original, ungroup/unlink the original video/audio clip, delete the original audio then shaza-freakin-BAM!
« Last Edit: January 20, 2011, 05:07:12 PM by Ryan »
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Ralphus

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Re: Removing Audio Noise Using Audacity
« Reply #2 on: January 20, 2011, 07:47:18 PM »
Good instructions.  Thanks.

Offline Skippy

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Re: Removing Audio Noise Using Audacity
« Reply #3 on: January 22, 2011, 11:31:23 PM »
Great instructions! Man people that have not found this forum yet are really missing some great tools and tips. Ryan, you really do go that extra mile. Thank you!
I'm an old film guy just playing catchup in this digital world. Help me out.

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Offline od

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Re: [Tutorial] Removing Audio Noise Using Audacity
« Reply #4 on: March 08, 2011, 05:30:10 AM »
WOW! This is great! Just downloaded Audacity. Great Tip!

Offline mbauer

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Re: [Tutorial] Removing Audio Noise Using Audacity
« Reply #5 on: March 31, 2011, 05:18:21 PM »
A very easy way to rip audio out of your original video files can be done with quicktime pro,  which is around $30.
Open the video,  choose export from the file menu and change the filetype to WAV or AIFF.

As for noise reduction,  Audacity might do a decent job, but I have to recommend "iZotope RX' Approx $350.
I've used the WAVES noise reduction suite in plenty of studios which sells for around $3500 and iZotope RX is 10 times better in every situation I've thrown at it.

One of the side effects of noise reduction is a garbled artifact commonly referred to as "Space Monkeys".
it sounds a little like when you stream really low quality audio from a website.

iZotope RX goes a very long way to reduce that garbled artifact, meaning you can reduce so much more noise before it becomes a problem.

You can also use what's called Spectral Repair.  Say for example you're filming a piano recital and someone in the audiences squeaks a chair loudly.  No problem,  you can remove it effortlessly without destroying the integrity of what you're trying to record.

Everything has limits of course,  but for noise reduction I would recommend nothing less than iZotope RX.

-Matt Bauer
Audio Director / Sound Designer / Mixer
E:  matt@bauer.net.au
WWW.BAUER.NET.AU

Offline Wanderingphotographer

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Re: [Tutorial] Removing Audio Noise Using Audacity
« Reply #6 on: October 02, 2012, 10:56:57 PM »
Thanks for the Tip, I am a Audacity fan too!!  8)
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