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Re: Audio editor/ DSP feature suggestions

Subject: Re: Audio editor/ DSP feature suggestions
From: Walter Knapp <>
Date: Sat, 19 Oct 2002 21:14:21 -0400
Steve Pelikan wrote:
> I'm putting together a progam that will perform audio editing and signal
> processing procedures and would appreciate any suggestions for features to
> be included --- especially features that would be useful for dealing with
> natural sounds. The goal at first is to provide procedures that aren't
> generally available on currently distributed programs. Since people use a
> variety of editors --- what are the most useful features of your favorite
> program?

I currently do most sound processing (as opposed to simple editing) in 
Spark XL. I do simple editing in Peak. It has a good waveform display, 
and is very easy to use for simpler stuff.

Spark XL has a setup where you can build a array of filters and run them 
simultaneously, including realtime. This they call FX Machine. I use it 
with Spark's own functions and VST plugins.

The most useful part is to put Spark's Sonogram in the last block. That 
will give you a good color high resolution sonogram, even in realtime. 
So you can check what your adjustments can do.

I use cutfilters, notch filters, various sorts of filters to bring up or 
kill different frequencies. I use Spark's adaptive noise filter (you 
train it by sampling the noise you want removed). I also sometimes use 
their declick/decrackle filter. Often I'm putting a sound simultaneously 
through a half dozen filters at once. The entire filter setup is savable 
for future use. I really like the multifilter approach. A big timesaver 
over doing filters one at a time.

Spark XL has quite a range of filters for modifying sound. Since for the 
most part I want the calls original I don't use those much.

Spark XL lacks a filter that works selectively by removing part of the 
dynamic range of the sound. I use SoundHack for that. Go in, for 
instance and remove the noise floor below the sounds you want. Say, all 
that's 50 dB below the max sound level. Not only useful for removing 
noise, but for some filter artifacts.

Though I've used it little Soundhack also has a binaural processor that 
allows you to position the sound in the field where you want. Something 
developed by NASA, I believe.

Don't forget MS Stereo processing. It's not that hard, but very uncommon 
in sound programs.

> 1) A WYSIWYG graphical spectrogram editor that lets you "paint out" a noise
> using the mouse and then transforms the sound back to time domain.

I have played with a couple crude versions of this, It seemed to have 
lots of potential, though the implementations I saw were too crude.

It would be a killer filter. I want!

> 2) A multi channel processor that computes the bearing and distance to a
> sound source.

This will pretty much imply a excellent database of mic characteristics 
to have any hope of accuracy. Bearing sounds easy enough, distance will 
probably not be possible unless a standard signal is played and recorded 
at the same time.

For the vast majority of nature recordists the 1 or 2 channel mono or 
stereo processing is as far as they will be going. It gets' complex 
setting up more mics in the field. Nature recording per se is not into 
the sort of micing that's done with music where each instrument may have 
it's own channels.

Walt




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