Old 07-11-2019, 02:42 PM   #1
hecramsey
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Default Audio Restoration methods

newbie looking for feedback, pointers to other online resources.

I am attempting to improve the sound on some really nasty live tapes. I have digitized the media to 24bit 192k wavs using best practices.

I am using Reaper and Cockos Plugins only. I am leary of jumping into heavy equipment without foundation with hand tools.

My method is:

1) I use ReaQ/BandPass to find, by ear, the cleanest bands of Vocals, low drum (the boomy part) high drum(the short sharp whack sound) way highs (usually guitars and cymbals) and that beefy/stringy lower mid range bass.
I know these sounds cover wide range of freqs, my goal is to exclude the muddy, non distinct mess in between these bands. I save these as presets and make a track for each band.

2) I apply compression to each track to raise the volume

3) I mix these bands with the untouched original track, setting levels by ear until it sounds "good" or "better" I don't know the tech lingo.

4) Then I use noise reduction (ReaFir) and EQ on the master track. (ReaQ again).

It's work in progress but I am happy with some of the results. I've improved the clarity while eliminating the muddy and boomy stuff somewhat. The untouched tracks have more presence, so its work in progress.

1)Is there a label for what I am doing, the slicing the track into bands and remixing?
2)I noticed if I duplicate a track the overall volume increases, even if the vol on each track is the same. So when I pile 4 compressed/eqd/whatever tracks on top of each other am I compounding artifacts, more than if I used multiband compression on a single track?. My ear frankly can't tell the difference. Its just way more complicated to work with ReaXCom.

Any feedback appreciated. THX!
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Old 07-12-2019, 09:48 AM   #2
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I'd try regular-old EQ first. Then you can split it into bands for further tweaking if necessary.


Quote:
1)Is there a label for what I am doing, the slicing the track into bands and remixing?
There are multiband compressors and dynamic equalizers which is kind-of the same thing from a different point of view. (A dynamic equalizer might expand as well as compress.)


Quote:
4) Then I use noise reduction (ReaFir) and EQ on the master track. (ReaQ again).
If that works, go for it! But, noise reduction is usually useless for live recordings (with artifacts/side effects making "the cure worse than the disease".)


Quote:
2)I noticed if I duplicate a track the overall volume increases, even if the vol on each track is the same.
If you bandpass filter and then re-combine, phase-shifts (a normal side effect of filtering) can cause "ripples" where the bands overlap. Or, it could just be the compression at the frequency-extremes of each band (again where they overlap).

A multiband compressor should avoid that but you may not get the precision or number of frequency bands that you need.
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Old 07-12-2019, 03:07 PM   #3
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reafir should be pretty good for tape hiss scenarios if wielded wisely:

may i recommend my usage tip:

https://forum.cockos.com/showpost.ph...5&postcount=23


also - i'd clean repair first before comping and eq sweetening - treating mid and sides seperately also powerful - eg. brighten a vocal up centre leaving anytting panned alone.
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Old 07-12-2019, 04:31 PM   #4
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Quote:
reafir should be pretty good for tape hiss scenarios if wielded wisely:
Of course I haven't heard this recording but the noise on a live recording is usually worse than "tape hiss".
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Old 07-12-2019, 04:32 PM   #5
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Quote:
Originally Posted by DVDdoug View Post
Of course I haven't heard this recording but the noise on a live recording is usually worse than "tape hiss".
yeh it won't fix the drummer.
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Old 07-12-2019, 07:38 PM   #6
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Originally Posted by DVDdoug View Post
Of course I haven't heard this recording but the noise on a live recording is usually worse than "tape hiss".
Thanks for all the good tips. I should clarify by noise reduction I mean tape hiss only. I grab a chunk of silent tape if available using RealFir Subtract.
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Old 07-12-2019, 07:43 PM   #7
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Cool, In which case the wet/dry riding trick should be quite helpful -

The idea naturally is it Leaves thing mostly alone - so no artifacts etc. when volume is high and masking any noise, then when needed, invisibly de-noises the quieter sections by just enough, (once set up).
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Old 07-13-2019, 07:21 PM   #8
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I'll just say it once and go away....

you would be amazed at how much work you would save yourself and how much better the results would be using iZotope RX7, which comes as 'do it all plugin' and also as it's own various parts, noise reduction, etc., etc.

Of course it's not free, but IMHO worth every penny.
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Old 07-13-2019, 10:00 PM   #9
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Originally Posted by hopi View Post
I'll just say it once and go away....

you would be amazed at how much work you would save yourself and how much better the results would be using iZotope RX7, which comes as 'do it all plugin' and also as it's own various parts, noise reduction, etc., etc.

Of course it's not free, but IMHO worth every penny.
I understand but want toget my hands dirty doing the work using basic tools for the experience. I could hand the tapes to a professional also but the best results is not my current goal.
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Old 07-13-2019, 11:25 PM   #10
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I do a fair amount of restoration work. Sometimes with recordings with a sound quality rating of "What the hell is that noise?!"

I find troubled recordings are often heavily compressed to begin with.
I often hear resonance saturation at some midrange frequency where it can almost sound more like the recording is an amplitude modulation of that resonance frequency!
Bass buildup is common. It's the other way around usually FWIW. The bass is the only part accurately captured. The highs and high mids are attenuated for various reasons. Purely an academic comment there.

iZotope RX is THE go to app for noise reduction and spectral editing. If you have a decent amount of this stuff to do, iZotope will prove itself on the very first job!

The saturation thing:
Parameter modulation with ReaEQ can be used to dial in a bionic multiband comp to zero in on that. That would be an example of an element of a recording gone dynamically wild to where you'd want to compress that element. The parameter modulation method with ReaEQ lets you get surgical with that.

Otherwise you probably want to avoid ANY kind of general compression or limiting. The poor thing is already going to be suffering from compression. It usually needs the opposite of that if anything unless we're talking about saturation frequencies gone wild.

Reaper really shines with its editing ability. When this kind of project leads you to slicing out little bits and sections and multing that out to separate tracks, there's pretty much nothing you can't do elegantly in Reaper.

For broadband noise reduction, there's really only iZotope RX IMHO. That ReaFIR in Reaper is so incredibly crude. It flat out cannot be used for noise reduction without doing such gross damage. Might as well use a crude low pass. At least it wouldn't be artifact riddled on top of all the content removed with the noise. Don't waste your time mangling audio with ReaFIR. (The one and only thing in Reaper that makes me say huh?) Reaper now has elementary spectral editing of a sort. iZotope RX will let you get down and dirty and work magic though and it's fast.

Reaper is god king DAW for sure. I love it and use it for everything audio based from live sound to studio production. iZotope RX is the tool for noise reduction and spectral editing though.

Last edited by serr; 07-13-2019 at 11:35 PM.
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Old 07-14-2019, 09:32 AM   #11
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Quote:
Originally Posted by serr View Post
I find troubled recordings are often heavily compressed to begin with.
These are untouched recordings. Can a recording compress "naturally"? Can clipping be seen as a crude compression, where the wave is flattened to a single uniform level?
Quote:
Originally Posted by serr View Post
For broadband noise reduction, there's really only iZotope RX IMHO.
When I say "noise reduction" am I referring only to tape hiss. Your comment still applies?

Thanks for the extensive notes. I understand about 1/4 of it, will do much research now!
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Old 07-14-2019, 09:48 AM   #12
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Quote:
Originally Posted by hecramsey View Post
some really nasty live tapes
Quote:
Originally Posted by hecramsey View Post
These are untouched recordings.
Can't very well be both!

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Originally Posted by hecramsey View Post
Can a recording compress "naturally"? Can clipping be seen as a crude compression, where the wave is flattened to a single uniform level?
Clipping would be the most unnatural and severe form of compression!
And again, troubled recordings - especially field recordings made with dictation quality devices are first and foremost compressed all to hell.

I would only call a pristine recording, free of any distortions or compression, "untouched". That YOU didn't ADD more compression yourself with a device intended to do that doesn't mean they aren't compressed all to hell to begin with. "flattened to a single uniform level" is kind of the literal definition of extremely compressed.


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Originally Posted by hecramsey View Post
When I say "noise reduction" am I referring only to tape hiss. Your comment still applies?
That's exactly what I was talking about yes.
FYI, it still takes care to isolate and reduce noise with iZotope! There's no click one button and you're done. You could mangle some audio just as severely with iZotope without some finesse. Just FYI. But between tricks like using the selection tool in iZotope for isolating the noise content or pre-filtering with an eq using iZotope as a plugin in Reaper, you can get great results with almost no damage to the program. (Should you choose. Sometimes some compromise is warranted depending too.)
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Old 07-14-2019, 11:41 AM   #13
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Quote:
Originally Posted by serr View Post
ReaFIR in Reaper is so incredibly crude. It flat out cannot be used for noise reduction without doing such gross damage. Might as well use a crude low pass. .
Why rule it out in such terms when folk have used it successfully with the correct settings and techniques.

Present an opinion by all means, but don't dissuade folk from investigating for themselves.

For noise that is unmasked at low vol levels, reafir and riding the wet dry with parameter modulation mix works very well.

Obviously izotope is very good, I have it, but for the right material reafir is a worthy option

Last edited by BenK-msx; 07-16-2019 at 07:59 AM.
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Old 07-14-2019, 11:59 AM   #14
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Quote:
Originally Posted by BenK-msx View Post
Why rule it out in such terms when folk have used it successfully with the correct settings and techniques.

Present an opinion by all means, but don't dissuade folk from investigating for themselves.

For noise that is unmasked at low vol levels, reafir and riding the wet dry mix works very well.

Obviously izotope is very good, I have it, but for the right material reafir is a worthy option
IMHO, the artifacts and program loss from ReaFIR working at its best are unacceptable and crude to the point of being fair to say it flat out doesn't work. I can somewhat appreciate that some people might consider the results using it with lower level noise acceptable with nothing else to compare to.

I don't know what else to say. This is literally the one Reaper tool that made me say WTF while everything else seems incredibly on point. I know how to dial these things in - I thought so anyway. iZotope RX doesn't just work transparently all by itself either and I'm aware of this. Try just taking a sample of noise without carefully bounding the selection and it will be nearly as crude and destructive, for example.

Someone just getting started might hit a wall and decide it's impossible to do (NR with ReaFIR). My point in that comment was more to not give up and instead try a tool that is actually possible to pull this off with.
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Old 07-15-2019, 10:36 AM   #15
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Can a recording compress "naturally"? Can clipping be seen as a crude compression, where the wave is flattened to a single uniform level?
Yes. Analog tape saturation is a unique kind of compression/limiting. Some people use tape saturation plug-ins.*


Tape begins to soft clip (limit) as you go over 0dB. Reel-to-reel machines tend to have quite a bit of headroom so you generally have to "peg the meters" before you start getting something that sounds like distortion. Of course, cassettes don't have as much headroom.


Then there's NAB (or similar) equalization which boosts the highs and cuts the lows during recording, then and cuts the highs and boosts the lows during playback. The result is further "softening" of the distortion harmonics . And, you can get a net-loss of highs if you "over-saturate".


Guitar players often drive the guitar amp into saturation. It gives a (sometimes pleasing) distortion effect plus compression. And the compression results in more sustain.



* I can understand using a tape saturation plug-in, but I DON'T like the idea of simulating the sound of an actual tape deck with hiss, etc.
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Old 07-15-2019, 02:19 PM   #16
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Quote:
Originally Posted by serr View Post
...
I thought the same until I had the wet/dry parameter modulation idea which made the whole thing 5x more intelligent. Used successfully and invisibly on hissy stuff, including recently.

Just sayin!
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Old 07-15-2019, 02:31 PM   #17
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This is great. thanks everybody. I am new to the whole "sound" thing so just hearing the correct terms for things is a great help.
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Old 07-16-2019, 05:57 AM   #18
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There are a couple tricks that make Subtract mode in ReaFIR more versatile.
1. As somebody mentioned, always put ReaFIR first in the effects chain.
2. Once you capture the noise spectrum, use Ctrl-drag on the graph to vary the amount of reduction. Lower = less reduction. Lower it till you no longer hear those 'bubbly' artifacts, then go a few dB further.
3. You can use parameter modulation in ReaFIR to back off the moise reduction during loud passages. Touch the wet/dry knob, click the Param button, select audio source, click the 'negative' tick box (so louder audio turns the wet/dry knob towards dry), and adjust the strength to taste. The idea is that when the audio is loud it buries the tape hiss, so you don't need to remove the noise until it goes quiet.

If the sound was captured by a cell phone or other portable, it's probably heavily compressed. You might try a downward expander to restore a bit of dynamic range. I use Cockos General Dynamics plug for this. Downward expansion has a side benefit of reducing the noise floor further as well.
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