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-   -   Audio clean-up options, Sound Forge (http://www.digitalfaq.com/forum/video-restore/1852-audio-clean-options.html)

SSStudio 12-11-2009 05:42 PM

Audio clean-up options, Sound Forge
 
Ok, I've seen the posts recommending SoundForge, and I've downloaded SF, Preset Mgr and the DigitalFAQ filter packs.

But before I get into that learning curve, is there an Audacity filter you could recommend to remove noise and hiss? I tried the accompanying Mazzoni Noise Removal filter and even with a pretty isolated noise profile, I got a terrible end result with "burbling" overtones no matter how much or how little filtering is accepted.

I'm guessing I'm way out of my league here...

admin 12-11-2009 07:02 PM

You need a clean noise profile.

The easiest way to do this is open your audio in SoundForge, zoom in fairly close, and then find a spot in the audio where all you hear is the hiss. There cannot be any other sound of any kind going on. Copy that small segment to a new file, and save it as a WAV. Be sure your new file is also 48kHz stereo.

Open both the full audio file AND the small noise print file in Audacity. Use Audacity 1.3, not older versions. You want the files opened in separate windows, not stacked on top of one another in the same window. When you do FILE > OPEN in Audacity, it will open them in separate windows. If you drag and drop, it will place them one top of each other.

Highlight the full noise print file once it's opened in Audacity, and then go to EFFECT > NOISE REMOVAL. Click GET NOISE PROFILE. Now you're done with the noise print sample file.

Go to your full audio, and highlight a portion that would make for a good preview, something with both quiet areas and voice/audio going on. If you don't select an area, then it will by default select the beginning of the audio file, and that's not always the best choice.

Go to EFFECT > NOISE REMOVAL. Most times, I find a Noise Reduction (db) setting of 12 to 20 to be best. Try 12 and then work your way upwards. Your goal is to remove as much noise as possible while also staying with as low a number as you can. The higher the number, the more actual audio you start to affect, muffle or distort -- and that's not good. Click preview, listen to your section, and you'll eventually find a decent setting.

Once you've found a good setting, cancel it. Go back to the audio file and hit CTRL+A (or pick Select All from the EDIT menu), and now go run the filter for real, on the whole audio file.

Audacity does muffle quite easily, so I suggest it ONLY for the worst of hiss. But unlike Goldwave, it does not usually leave behind metallic-sounding audio artifacts. (However, Goldwave can reduce far worse noise than Audacity can handle!) For most minor hiss issue, the DigitalFAQ Paragraphic EQ Presets pack is your best bet, using SoundForge (either professional version or the consumer "Studio" version). There are at least 20 or more options in there, to reduce, hide or outright remove hiss.

As a Premium Member, feel free to attach small WAV, MP2, MPA, MP3 or AC3 files (7.99MB filesize max) to your post, and I'll take a look at it, give some suggestions on filters.

SSStudio 12-12-2009 11:58 PM

Tried, but alas...
 
2 Attachment(s)
Maybe I don't understand what I'm hearing.

I attached a 43 sec .wav sample out of a 3.07 min Cathedral Organ piece. The source is mono (not stereo). I also attached a 2.2 sec noise sample.

Nothing I tried gave me a satisfactory result from the noise reduction filter. I couldn't stand more than a 5 db suppression without getting a weird erratic muffle patter overlay. Are these clicks that have been "noise removed" ? I'd rather have the more consistent hiss and just quiet it marginally (~4 or 5 db) before it becomes noticable. Not much improvement.

Is there something alse you see going on?

admin 12-13-2009 03:41 AM

4 Attachment(s)
Audacity was able to remove the noise, but it did introduce artifacts. This happens in both audio and video restoration. When you remove one problem, it's not uncommon for another one to take its place. Or for a more minor issue to then become the now-dominant (and more easily seen/heard) problem.

SoundForge and Goldwave handled it differently. Attached are several versions, including my own Audacity work, which followed up the NR with an EQ adjustment.

Sound Forge 6 work was using the DigitalFAQ Paragraphic EQ preset "Hiss Cut 2", followed by a new custom preset temporarily called "Test 10". This was a quickly done preset, it wasn't tweaked oh-so-perfect. More of a proof-of-concept still, at this stage.

Sound Forge 9 Studio work was done using custom settings on the Audio Restoration tool, under the Tools menu.

Goldwave was a quick NR (default scanned setting, based off initial audio from the full sample), followed by the Pop/Click filter on the passive preset.

The hiss was removed, and the secondary noise revealed has also been curbed. The tonal quality varies a bit, but I was not tweaking for this. Again, all for proof of concept, to show what can be done quickly, with some guidance on how it got there.

admin 12-13-2009 03:43 AM

3 Attachment(s)
Here are those setting talked about in the above post.
See images:

Attachment 501

Attachment 502

Attachment 503

SSStudio 12-13-2009 05:30 PM

Thanks. I'll try and digest this and get back to you. I'm curious to understand how you determined the EQ frequency profile.

SSStudio 12-15-2009 06:24 PM

Response
 
Ok, here are my thoughts after listening to each sample repeatedly, studying speicifc segement outcomes, and comparing to the original.

Ranked Better first:

1) Goldwave NR + Pop/Click: Best in hi freq and across most freqs. Left behind metalic-sounding artifacts...too bad...it was otherwise darn good.

2) SF6 HissCut 2: Ok NR but you can tell the hi feqs are pretty restrained and looses "voicing" in the upper pipe organ notes at 23.0 secs thru 43.3 secs.

3) AudacityNR + EQ: Too heavily muffled across all freqs. Distant sounding fuzzy clicks.

4) SF9 CustAR + Pop/Click: Distorted overtone like the inside of a 55 gallon steel drum. SF6 was more balanced.

Just my opinion.
Does that help determine a direction?
Maybe with tweaking SF9 can approach Goldwave acheivement without the artifacts (?).

admin 12-15-2009 07:37 PM

1. There are anti-metallic filters in SoundForge (more DigitalFAQ presets), to use after GoldWave. This can sometimes help.

2. True, there is some loss here. But again, the filter work done above was proof-of-concept. With more tweaking of the EQ levels, mid and high values can be adjusted to your liking, I'm sure.

3. I don't really know that I can agree here, about severe muffling. I'll explain in a bit. The NR+EQ however, is not as good as some of the others. Audacity is tripping up BADLY on the NR step, leaving back some kind of odd mess, as you noticed in the first post.

4. Again, this was a quick proof-of-concept. It did aggressively go after the hiss, with minimal attention to maintaining the music values.

HOWEVER...

Audio and visual material is not always as exacting as some would think. There are psychovisual and psychoacoustic issues to deal with, as well.

For example, when you have an audio waveform saturated in a high-pitched hissing sound, it attentuates and affects the underlying sound. What you perceive as pitch or tone is actually noise affecting the actual pitches and tones. So trying to retain 100% of the sound as you think it should exist is an impossible task. You'll instead want to mask as much as the noise/hiss as possible while at the same time retaining as much as the "good sound" as you can. The keyword is "as much as" and not "all".

ASIDE: Psychovisual issues are similar. For example, where people perceive grain and artifacts to be "detail" where no detail actually exists. Or when LCD/TV colors are accurate (or inaccurate), and their sensitivity to backlit displays causes them to think otherwise.

At the end of the day, your goal is to remove the noise. Even if the underlying unrestored audio has better-perceived pitch/tones, nobody wants to listen to audio that has cooking bacon as the accompanying harmony.

"SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS" was not part of any concerto I ever played! :D
Nor "bzz bzz clk clk" or anything else.

Sometimes you'll have to sacrifice a bit more audio fidelity, in the interest of overall enjoyment -- i.e., removal of the obnoxious noise harmonies.

Given what you've said so far, I think your best bet is Sound Forge (6 or higher -- any of them), using the standard EQ work as I did in SF6. And the tweak the values, starting off with what I did. Feel free to adjust the EQ levels to "put back" more of the mid and high tones, but without re-adding the hiss/noise again.

I heard loss in some of the highest pitches, yes, but the noise/hiss shared the same frequencies, so they were carved into a bit. I don't know that there is any way to fix audio without at least slightly affecting values. There are many ways to do this, between software, hardware and sub-methods therein.

Always remember the goal of restoring it to "make it better" and not "make it perfect".

SSStudio 12-15-2009 08:51 PM

Thanks for the help. It makes sense to me.

I guess I should go ahead and install SF9...which I haven't done yet.
I assume you don't think Goldwave offers any advantage.

admin 12-15-2009 09:10 PM

Well, GoldWave is a valuable tool in my line-up. It has strengths (removing even the worst of hiss/noise), and weaknesses (metallic/electronic after-noise). If you can work it into your audio restoration workflow, it may be useful. Then again, maybe not. For this one example, it's probably not the very best choice.


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