audio editor

[Tom Metro]

Derek Martin wrote:
> Tom Metro wrote:
>> -It locked up X twice.
> 
> Might be a Ubuntu bug (and possibly not specific to audacity)?

Yes, that seems likely. It's happened a few more times with Audacity, as 
well as with Gnome Wave Cleaner (gwc), so its likely something in the 
sound driver or some other common library.


>> -The compressor doesn't compress. The expectation is that dynamic range 
>> compression should take any audio below a threshold and amplify it, 
>> while leaving peaks above that threshold as-is. 
> 
> That sounds like the opposite of what I expect compression to do:
> reduce the peaks, and (possibly) amplify the signal to the extent that
> produces no (additional) distortion.  

Compression is reducing the dynamic range such that the difference 
between the highest volume portions and lowest volume portions is 
minimized. A common application for it is to make commercials sound 
louder (and presumably more noticeable) by artificially boosting any 
quiet bits. Reducing the level of existing peaks would still fit the 
definition of dynamic range compression, but it wouldn't fit the typical 
use case.


>> I'm hoping there is something better available.
> 
> I expect that there is, ...but audacity has always been the
> recommendation...

I've looked at the feature lists of a pile of alternatives, and 
installed a few, but so far nothing has been better than Audacity.

I'll comment first on the ones people have suggested here...


john saylor wrote:
> you can look at ardour [complete linux audio workstation, but that
> might be overkill]. i think you might just need to work over your
> files a bit more.

Ardour looks great, and it's not that it's overkill, but it's the wrong 
tool for the task. Ardour comes into play when you are compositing 
multiple tracks and layering effects, while I'm doing essentially sample 
cleanup work. Like you said, I need to work over my files.


> or maybe learn some more about dsp and computer audio.

I have hardware and software DSP experience and have worked for pro 
audio companies, and although it has been a while, I don't think that's 
the problem. My expectations might be unrealistic, though...


> and complaints about the ui of an open source project- well, those
> don't really go too far [diy!] ...

It's true that the UI doesn't get much priority in open source, but I 
also believe that well run open source projects should solicit and use 
customer feedback. The "patches welcome" mentality is obsolete.


Ted Roche wrote:
> You might want to check out the Levelator (r):
> http://www.conversationsnetwork.org/levelator/

The Levelator "adjusts the audio levels within your...audio file for 
variations from one speaker to the next, for example. It's not a 
compressor, normalizer or limiter although it contains all three. It's 
much more than those tools, and it's much simpler to use."

Neat idea, but at the moment my biggest challenge is noise removal, 
rather than normalizing. The project also looks like it might have gone 
stale, as the latest build is targeted for Ubuntu Feisty Faun.


Danny Piccirillo wrote:
> Have you given Jokosher a try? 
> http://www.jokosher.org/

Also looks nice, but is aimed at the same tasks as Ardour. Great for 
making music, but not so optimal for cleaning up audio.

There's a lot of overlap between the two types of programs, and the 
distinctions is somewhat arbitrary, but most tools are either optimized 
for mixing multiple tracks and applying effects, which fall into the 
Digital Audio Workstation (DAW) category, or they're better for 
modifying sound waveforms, which I'd call sound editors.

Other DAWs I ran across:

DAP
http://www.macs.hw.ac.uk/~richardk/
(Says in it's feature list, "No noise reduction, filter based DC 
removal...")

Rosegarden
http://www.rosegardenmusic.com/
(More about MIDI than digitized audio.)

GLAME - GNU/Linux Audio Mechanics
http://glame.sourceforge.net/index.var
(Last release was in 2007.)


Sound editors similar to Audacity:

Sweep
http://www.metadecks.org/software/sweep/

(Similar feature set to Audacity, except it adds some functionality for 
processing live audio and features for DJs. It doesn't appear to have 
Audacity's noise reduction functions (at least not from what they list 
on the web site), but it works with LADSPA plugins. The last release was 
April 2008, so it's looking a bit stale.)


ReZound
http://rezound.sourceforge.net/
(Has "noise removal" on its wish list, and points to GWC (see below) for 
that functionality.)


A sample editor:

LAoE
http://www.oli4.ch/laoe/
(More about generating wave forms than cleaning them up, though it does 
list notch filtering on it's feature list, which can be useful. Hasn't 
had a release since 2003.)


Plugins:

Linux Audio Developer's Simple Plugin API (LADSPA)
http://www.ladspa.org/

linux DSP
http://www.linuxdsp.co.uk/

And a bunch of other sites listed on the ladspa.org site. I browsed 
through several and didn't find any noise reduction plugins.


So far the best alternative I've ran across has been:

Gnome Wave Cleaner
http://gwc.sourceforge.net/

which can denoise, declick, and decrackle, plus has high-pass/low-pass 
filters.

But in practice it had a buggier UI, and after more persistence with 
Audacity, didn't denoise as well.

I kept working at Audacity, and was able to get the denoise tool to work 
for some types of noise. I still haven't been able to get rid of the 
static or crackle sound (which is why GWC's decrackle filter sounded 
promising). And I think I can baby along the normalization to achieve 
the result I want by selecting small portions of the audio for each 
application of the filter. Ultimately I might not be able to restore the 
audio to an adequate quality and may just need to scrap it.

  -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/