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Tips using Izotope RX2 - umpredictable noises
Old 13th March 2018
  #1
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Thread Starter
Tips using Izotope RX2 - umpredictable noises

Hello !
I'm new with Izotope RX2 - I've got the software for not long (rental) and I would need advice to get rid of some accidental noise. The recording consists of a modern classical music concert and the noise are very short : mostly page turns, foot thumping on the floor, clicks from a music stand that was hit, etc. The annoying noises occur mainly in silent parts.

RX Users, what tools would you instinctly use ? Noise removal ? spectral repair ? I would love to spend hours learning this software, but time is against me this time, and help would be greatly appreciated !

thanks in advance.
Old 13th March 2018
  #2
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Version two? Rental? It's 2018, so I disapprove of that.

I would get a later version and use Spectral Repair for most of it probably, given that it's classical. Possibly a de-clicker at times, but I'm guessing that might be difficult.

Honestly, being new to RX and fixing classical while time is against you seems like a bit of a challenge I have to say.... Go on the Izotope website and watch their videos if they're still there. Maybe YouTube has them. Easier to look/hear than to read about it here.
Old 13th March 2018
  #3
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Thread Starter
Thanks Mattias !

anyone else with an idea/who has encountered similar problem ?
videos : nothing close to what I experience on my recording.

I really have RX2 now, low rent, no need of RX normally, so I'm totally fine with it thanks for your concern.
Old 13th March 2018
  #4
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Old 13th March 2018
  #5
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Thread Starter
Yes, I watched some of these on youtube.
Old 13th March 2018
  #6
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Spectral repair - replace for low frequency, partials & noise or pattern for higher frequency material.

You can also copy spectrally from a clean area and paste over the offending section.

Randall


Quote:
Originally Posted by amsylvestre View Post
Thanks Mattias !

anyone else with an idea/who has encountered similar problem ?
videos : nothing close to what I experience on my recording.

I really have RX2 now, low rent, no need of RX normally, so I'm totally fine with it thanks for your concern.
Old 13th March 2018
  #7
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Thread Starter
Thanks Randall, very interesting. I would avoided patrials+noise and it worked for one of the noises.

another simple question - is there a quick way to compensate db reduction when spectral repair is applied ? if these two tools are selected (Gian and spectral repair), I don't see the way to link them together.

Thanks again - I might make it on time !
Old 13th March 2018
  #8
Lives for gear
 

If i understand you correctly, you shouldn't have to compensate when removing some of the noises that you mentioned as the software generally does a good job of that on it's own.

I don't think there is a way to link Gain and Spectral Repair together.

Randall


Quote:
Originally Posted by amsylvestre View Post
Thanks Randall, very interesting. I would avoided patrials+noise and it worked for one of the noises.

another simple question - is there a quick way to compensate db reduction when spectral repair is applied ? if these two tools are selected (Gian and spectral repair), I don't see the way to link them together.

Thanks again - I might make it on time !
Old 13th March 2018
  #9
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Thread Starter
Well, the level is dropping in some cases, I'll just edit the corrected audio in the original...
Thanks again.
Old 14th March 2018
  #10
I used to own RX2, but I think I'm running RX6 now. Really there's not a lot of difference between them for what you want to do. I also use the Sequoia's built-in spectral editing functions a lot, and the principles are basically the same. But be prepared for me to use slightly different terminology than you may see in the RX2 dialogs, because I don't remember what stuff is called in one program vs. the other.

For cleaning up noises in live recording of classical concerts, you should spend most of your time in spectral repair. Each type of noise will be handled a little differently. You will want to optimize both the length of the processing region and the FFT window length. Generally speaking, clicks call for shorter FFT window lengths and thumps call for long ones, but what's going on musically can affect that. If you're patching over lower frequency stuff, you need a much longer FFT window to get sufficient spectral resolution. It's also important to choose the right kind of crossfade for each problem. You can use slower crossfades when the music is changing slowly. Obviously a short processing region requires shorter crossfades, but if that doesn't work, try expanding the processing region and using longer crossfades. Remember that the algorithm is interpolating based on material to either side of the processing region, so that material needs to be clean. If it isn't, make the processing region wider. If the noise causes a reverberant decay in the room, you need to account for that. Either widen the processing region to include the decay, or use asymmetric interpolation and/or crossfades. Another trick is to do two steps of cleanup, for example a short processing window and then a long one.

To fix things in a spectral editor, you need to be able to both hear them and see them. If you can only hear them, monkey around with the spectral color mapping options until what you're looking for pops out on the display.

You can use noise reduction at the beginning if fading in the room tone creates a distraction. Sometimes you need it for other quiet parts, but usually folks won't notice HVAC noise once the actual music is underway. In general, you want to use as little of this tool as possible because it creates sonic artifacts. Try the "play what I'm removing" option and back things off if you hear anything that sounds like music. It's often better to attenuate the room tone rather than reduce it to zero. Take time to find the most representative noise sample to train the algorithm on -- no extra transient noises to confuse it. Also, think about what part of the noise is actually objectionable. Some tools let you modify the frequency response of the noise reduction curve. If you can get away just reducing the very low frequency stuff, you can avoid a lot of artifacts. When you can't do that, pay attention to the smoothing parameters. It's quick, narrow-band spectral gating that causes the "martian breebles" you also hear in low-rate MP3 encoding. There's usually some smoothing control that will make those transitions less abrupt.

It may seem counterintuitive, but don't do all your work on headphones. Some artifacts only become obvious when you're listening on speakers.

Good luck,

David L. Rick
Seventh String Recording
Old 15th March 2018
  #11
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Thread Starter
Hello David, so many thanks for sharing this ! it helped.
up to here, I'm impressed with the results - some of the noises will remain, but fewer than I thought.
(I'll sure listen on speakers too at some point !)
Cheers.
Old 16th March 2018
  #12
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There’s a simple trick in the RX editor, I’ll call it “spectral copy-paste” - find a silent part (or free of accidental noises), select it, press copy, and then select (with the lasso or rectangle tool) the noise you want to remove and paste over it (I think the shortcut is ALT-SHIFT-V on mac). The “source” background noise should match the “destination” background noise. This works sometimes...
Old 19th March 2018
  #13
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Thread Starter
I got that just after finishing Nice little trick. Next time I use RX I guess...
I ended up using spectral repair for most, replace and especially partials+noise. Had to edit the files in the original to compensate for the levels, in some case.
Thanks all.
Old 20th March 2018
  #14
Spectral Editing: you thought Autotune was cheating

Quote:
Originally Posted by Dragomir View Post
There’s a simple trick in the RX editor, I’ll call it “spectral copy-paste” - find a silent part (or free of accidental noises), select it, press copy, and then select (with the lasso or rectangle tool) the noise you want to remove and paste over it (I think the shortcut is ALT-SHIFT-V on mac). The “source” background noise should match the “destination” background noise. This works sometimes...
I did something even scarier once. I was editing a live piano performance and the performer complained that on one very quiet chord, the low note hadn't spoken properly. So we "flew in" only that note from a couple bars earlier where there was a different chord with the same root. I know, I'm going to burn in hell.

David L. Rick
Seventh String Recording
Topic:
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