Noise Reduction
Wind Noise - I spent a few minutes reading the reviews about Magix Audio Cleaning Lab, and I have to say that for the price ($35 at Amazon) it looks like a very good deal. And considering we've got someone here who recommends it, it might be something to take a good look at.  Dave Stone
 
  • I think you'll find the Liquid noise reduction filter to be less than satisfactory (in fact, I find it unusable).

    Here is an audio clip with a lot of wind noise in it: Common Loon

    Here's the same clip with 2 filters on it (Leveler and Liquid EQ): Common Loon - Corrected

    The Leveler is placed on the track header. The Liquid EQ filter is on the clip itself. Here how the Liquid EQ parameters are set:



    The leveler requires no parameters to be set.

    While this doesn't get rid of all the wind noise, a single notch filter with the leveler can take unusable footage and make it acceptable.
     
    Dave S.
  • Getting back to the simpler side of life (notch filters), the best one (I think) is the Liquid EQ equalizer. There's no real documentation for it in the manual. Here's a basic course on audio for videographers that I did at Liquid Univeristy a while back:

    Audio Course

    Please note that this is an exported powerpoint slide presentation. It will work in both IE and Firefox, but (being a MS product) it works better with IE.

    Slides 31 - 37 discuss notch filters and the Liquid EQ equalizer. Please also note that this was designed to be done as a live presentation, so the slides are not as fleshed out as they might otherwise be.

    If you look at the example on slide 34, you can see a notch filter with the various parameters set and what it looks like on the graph. If using Firefox you may want to extract that slide or zoom it to 200% to see it better. Here's what it looks like:



    In this example, there are 4 control points active. Point 1 is the low shelf at 100hz This means that no frequencies below 100hz are affected by this filter. Point 2 is at 850hz and point 3 at 1041hz. Both of them are set to reduce the volume by 24db. Point 4 is the high shelf at 12khz. All frequencies above that are reduced by 2.5db.

    As you can see from the graph, There is literally a notch between which everything is reduced by 24db. What you need to do is to find the frequency around which you have your hum (start with the 50/60hz hum given off by electrical equipment).

    You can remove a great deal of unwanted noise by using a set of notch filters on your audio.

    Hope this helps.
     
    Dave S.
     

 

 

How do you correct imperfections in audio recordings - generally recorded on the audio tracks of the video camcorder ?

Some general consensus of good tools - 

Link to Stephen Noe's comments - MoreAudior.htm

 

SoundSoap - $99 version
Audition (also part of Premier Pro package as well as a stand alone)- Tutorial on Noise Reduction using Audition
Magix Audio Cleaner gave a user good results in the past and it's not expensive. 
"Audacity" http://audacity.sourceforge.net/ - Free

 

  •  Kenneth_L:  (forum link)
       I did a bunch of filming and forgot about the background noise.  I have a major problem with an Air Conditioner.  So I have kids talking and playing and I want to filter out the A/C in the back ground. Any ideas?

    Yet another reason not to quit my day job :)


    A1. It's not hard to get rid of if you have the right tools.  SoundSoap will get rid of AC noise very easily.  I use SS2 ($99) as a plugin to Wavelab.  Works excellently and I get the acillary benefit of mastering audio with great precision in Wavelab.  Noise suppression and mastering all in one 'send to wavelab' session is a godsend.   S.Noe

    A2  A/C noise is very hard to remove. It's effectively white noise, so taking a noise print and removing it causes a notable loss of volume and audio quality for everything else. If you're using a program that captures noise prints for subtraction, apply the filter multiple time with small values instead of once with a large reduction value. This tends to reduce the amount of flanging these filters can cause. D Stone

    A3.   Out of the 4 Audio editing applications I have on my editing suite, the open source application "Audacity" http://audacity.sourceforge.net/ has one of the easiest "white noise" removal tools. It is very sensitive and has worked well for me on many occasions. I will forwarn you though, it can be a tad slow to process.  All you have to do to make it work is select an area of audio with the background noise involved, preferable without other noise or minimal noise, let it analyze that section and then apply the filter to the rest of the audio track. Be careful though, if you push it too much, it will make your legitimate audio sound a little goofy. You can X-Send Audio from the Liquid timeline into Audacity.  Give it a shot, its free... can't hurt.  J Figura

 

 DStone
 
Re: Sound level correction. Help request
 
You should look for a noise reduction package, one which captures a noiseprint and removes that noise from the clips. I use Sony Noise Reduction 2.0 with SoundForge, but I would also recommend looking at a product from Bias called SoundSoap. It's about 1/3 the cost of the Sony product and is reported to work quite well. The Sony product is a DirectX filter, whereas the Bias one is a VST.  Please note that I don't use SoundSoap myself so I can't give a direct comparison with Sony. I don't have the hotlinks for these available, but you can find them on the Web easily enough.

Regardless of whose product you're using, when reducing noise in this manner make multiple passes with a small amount of noise reduction rather than 1 pass with a large amount. Large amounts of noise reduction can result in flanging and other audio artifacts.
 
Dave S.