Dialogue post-production - removing unwanted background elements

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dariunas

dariunas

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Hey all,

I have an issue here. Had a contact who had done some video recording and needed the dialogue audio cleaned up. I did some music to it and said I'll be able to clean up the audio too (you can see where I'm going with this)

He did a little cleaning up of his own, though not being much of an audio specialist, he used something called Soundtrack Pro that comes bundled with Final Cut on the Mac.

I'm using Sonar 7 and Sound Forge and embarassingly, could not get anywhere near his results. I kept destroying the detail of the speaker's voice too much when I tried to EQ out the hiss/rumble.

Listening back to his mp3 version, I noticed that there was an artificial edge to the audio. You probably wouldn't notice it much if you weren't listening for it, but tucked away in the background, I noticed quite a strange pitch change, which I think was the artifact of the background machine. I don't know what kinda of plug-in or algorithm technique was used, but I couldn't come close - it seemed to like it had 'filled in' the speech after removing the background noise.

So, this is something I really want to get a handle on as I'm trying to get into sound design. Can anyone offer a little advice or a good external resource on this please? I have the ear to isolate what's going on with the sound; I'm either taking the wrong approach, using the wrong plug-ins, or not using them right... :(
 
As a general rule, if the unwanted noise is in the same spectrum as the wanted speech there's nothing you can do about it. There is no program able to separate the noise from the wanted material because the two are organically mixed together in the file.
The only exception is when the offending noise has a predictable regularity about it such as a hum or tone. If the timebase is accurate enough you might be able to construct enough of a waveform of it if it appears alone long enough in the file without the program added. Mix it back into the original file in antiphase. You have to be really accurate in phase alignment and level.

"Cleaning up" noisy audio is so easy to say but so very hard to achieve. There's been a program out there amongst the many called "Sound Soap". I think the product name describes more our hopes and wishes rather than what can be achieved in practice.

The problem is that the background noise has essentially obliterated the quiet portion of the speech or music. The information is no longer there. To expect the software to recreate information that's not there is of course asking for a miracle.

I believe the best programs have come from Sonic Solutions and Cedar but you would have to decide if the cost is justified.

Can you post samples? That might help us to make more informed comments. Unaltered files would be best.
 
+1 on the spectral analysis tools.

You may already have the tools you need built into some of your software packages. Look in the editing section for "spectral view." This is a unique way to view frequency (instead of amplitude) to isolate problems.

For an example of how this works, take a look at this little tutorial video I made to remove noise.

Click Here.

As I said, spectral view works similarly for most DAW software that does include it. Or you could always add a plug-in to achieve this like Tom Waltz mentioned.

EDIT: By the way, that "artificial edge to the audio" that you mentioned may be caused by the mp3 compression scheme. You would have to listen to the original edited wav to know for sure.
 
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Raw Depth, your noise removing tool did remove that 5500Hz tone but the black hole shows that it removed all 5500Hz material, not just the feedback. The effect is no doubt an improvement in that sample as most of the guitar energy is well below 5500hz anyway and so there's not much important guitar information lost along the way.

In this case, the tone was regular, had no real harmonics and so was easy to EQ out.
It's easy to remove stuff like that because of those reasons. Other stuff can be far more difficult.
 
Tim Gillett said:
Raw Depth, your noise removing tool did remove that 5500Hz tone but the black hole shows that it removed all 5500Hz material, not just the feedback. The effect is no doubt an improvement in that sample as most of the guitar energy is well below 5500hz anyway and so there's not much important guitar information lost along the way.

In this case, the tone was regular, had no real harmonics and so was easy to EQ out.
It's easy to remove stuff like that because of those reasons. Other stuff can be far more difficult.
Click to expand...

You are correct. Some types of noise can never be cleanly filtered out if it spans the entire frequency spectrum. (At least, not that I know of.)

My intentions were to show the OP what the tool looks like. I figured it would stir enough interest for him to go look for it within his own software and experiment before spending hundreds $ on anything else.

I thought it may be worth trying. But yes, as with anything, it has its limitations.
 
You mentioned SF, I take it your version doesn't have the "Noise Reduction audio restoration plug-ins"? I've got and older version and got the "Noise Reduction" plug-in not sure if it the same as the newer version of SF or not, but it works pretty good, I've used it in some indie films.
 
Thanks for all the responses, guys. Things are becoming a bit clearer regarding the limits of what can be done and the tools used to do it.

This is the software used the the video editor which blitzed my efforts,
http://www.apple.com/finalcutstudio/soundtrackpro/restoration.html

I have Sound Forge 7 but I don't think I have any noise reduction or clean-up tools in there. Adobe Soundbooth seems to have some tools in there, but Isotope RX looks pretty excellent and could be worth investing in as a specialist tool as I like working in Sound Forge and not keen (or maybe just lazy) on learning another editor just for a few plug-ins if I can avoid it...

Looking at these, my first impression is that I think my approach with frequency cutting was off and that a dedicated plug-in was the way to go.

What I'd like to do as Tim suggested, is post some examples up so you have a better vision (sound) of my issue on this, which I'll do a bit later or tomorrow.

Thanks again everyone
 
I just watched your video, Raw Depth. I had been seeing a similar usage in Isotope RX, and the example here is a little bit clear cut due to the isolated frequency of the 'offending' sound. Having said that, it was nice seeing it done manually as most demo vids of these kind of software just have plug-ins to doing the work, so thanks for that.
 
Ok, so I have downloaded and used Isotope RX and within 20 minutes of installing it, the sound was cleaned up brilliantly! Thanks for the recommendations. I did try out Adobe Soundbooth also. I liked it's interface which is really nice, but a lot of it's effects seemed really 'fixed' in their parameters. The noise reduction tools were ok, but Isotope was a lot more effective in removing the noise without strange flanging effects etc. it's also at a pretty decent price for what it is, so that's my next buy. New monitors will have to wait Thanks all! Very happy now I know where I was going wrong :)
 
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