Ladspa-DSP plug-ins in SND

As previously stated LADSPA is the Linux Audio Developer's Simple Plug-in API. LADSPA provides a standard way for `plug-in' audio processors to be used with a wide range of these packages. Dave Phillips in his O'Reil ly article, clearly explains what a 'simple plug-in' is as follows:

A plug-in is a software module that adds new functions or extensions to a host application, without the need to recompile the program. The plug-in functions are stored within a shared object file (*.so in Linux, *.dll in Windows) that may contain one or several plug-ins. The application provides the entry points to dock an object, and the new functions are immediately available. The user accesses the plug-in as a normal part of the host's interface.

Therefore, plug-ins add flexibility to Snd or the ability to do additional signal processing to an existing sound. Many of the plug-ins that are available in Snd are Open Source version of plug-ins used in other operating systems. Many of them are improved versions of commercial products done by Steve Harris and a talented group of DSP hackers. You are encouraged to try most of them. You can find more information about each plug-in at the LADSPA web page and its links to the developers.

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

 		           /usr/lib/snd/scheme/       

1. First start by opening a new sound or a sound to be processed on Snd:

   
    		 (new-sound "/zap/test.snd")        
   
2. On a terminal shell copy ``ladspa.scm'' from the Snd sources directory:

   
    		 cp /usr/ccrma/lisp/src/snd/ladspa.scm  /zap/        
   
3. you can also copy the ladspa help as a reference for many plug-ins:

   
    		 cp /usr/ccrma/lisp/src/snd/ladspa-help.scm  /zap/        
   
4. Make sure Snd's listener window is active and somewhere around the editor window. Now you can load both scheme files as follows:

   
    		 (load "/zap/ladspa.scm")        
   
   and,

   
    		 (load "/zap/ladspa-help.scm")        
   
   Now 'ladspa.scm' should load and if everything has gone well, you should get the familiar Guile response,

   
    		 #<unspecified>        
   
   you should now have a new ``Ladspa'' menu along with other Snd menus on top of Snd's GUI. Now it's a good time to take a look at this enormous collection of LADSPA plug-ins to be used at your own discretion.

5. To apply or process a region or a complete soundfile, just make active the soundfile window you want to process, select the region or the whole soundfile and, then from the LADSPA menu choose the plug-in you want to apply.

The following plug-in categories are available in Snd

• Utilities

  Ambisonic, Tap Pink Fractal noise, signal sum, signal product, signal difference, signal ratio, signal branch, quantizer, karaoke, ms to stereo and many others.

• Generators

  Oscillators, random wave generators, analog voice, granular scatter processor, syn drum , gong model, harmonic generator and many others.

• Simulators

  Step sequencer, tap rotary speaker, tape delay simulation, valve saturation, valve rectifier and many others.

• Time

  Delays, flangers, phasers, chorus, tap reflector and signal shifter.

• Frequency

  Measurement, filters, EQ and frequency modulators.

• Amplitude

  Amplifiers, wave-shapers, modulators, distortions and dynamics like gates, limiters and compressors.

• Spectral

  Bode frequency shifter and Impulse convolver.

• Uncategorized

  10 Band Eq, Mono Amplifier, Pulse-VCO, versatile plate reverb and many others.