Digital-Signal-Processing with SND

As you might figure SND is a full featured signal processing toolbox. Most standard techniques have been implemented and new ones can be programmed. As a starting point you might want to try copying ``new-effects.scm'' to your working or `` /zap '' directory and then load it in the scheme listener with the following steps:

 		     cp  /usr/ccrma/lisp/src/snd/new-effects.scm /zap/       

and then on the SND listener,

 		          (load ``new-effects.scm'')       

Not by magic notice that there is a new menu called ``effects'' on top of the ``SND'' GUI. This is a standard collection of DSP tools which might also help to understand and preview how audio signals can be manipulated. As a bonus just for trying, you get sliders to control most of these effects.

Of course you are encouraged to try all of these effects but make sure you already have an opened sound. If you are not happy with the processing you can undo it by C-x C-u or simply ``undo'' in SND's edit menu. If you are really curious about signal processing you can also look at the code and customize these filters or create new ones. Make sure you share them with the DSP and SND communities.

The effects include:

• Reverse soundfile.
• Normalize soundfile.
• Gain change
• Rubber soundfile
• Filters, bandpass, lo-pass, hi-pass and others.
• Flange effects
• Delay effects like echo, filtered echo and modulated echo
• Frequency effects
• Modulation effects
• Convolution
• and more

Most of these are either simple calls on SND functions or use functions in the other scm files. If you are using two or more channels sound-files the actual processing follows the sync chain or the currently active channels but aside from reverb it is good practice to work with DSP effects on each channel separately.

N O T E: on PlanetCCRMA Linux machines outside CCRMA network, Snd sources are located on,

 		           /usr/lib/snd/scheme/       

Alternatively, if you decide to download Snd sources yourself, or if you want to compile Snd, untar a snd-X.tar.gz file by using the command:

 		     tar xvzf snd-X.tar.gz       

your sources will be at

 		     ./snd-X       

where X is the Snd version. Instructions for compiling Snd are part of the documentation described at the links on: §9.13