I am looking at some basic real time digital audio processing:

• http://code.google.com/p/rt-digital-audio-processing

As often happens, discovering new problems, I am discovering already existing solutions.

The Linux Audio Developer's Simple Plugin API (LADSPA) is a standard that allows software audio processors and effects to be plugged into a wide range of audio synthesis and recording packages.

PortAudio is a free, cross platform, open-source, audio I/O library. It lets you write simple audio programs in 'C' that will compile and run on many platforms including Windows, Macintosh (8,9,X), Unix (OSS), SGI, and BeOS. PortAudio is intended to promote the exchange of audio synthesis software between developers on different platforms.

CLAM is a full-fledged software framework for research and application development in the Audio and Music Domain.

Libsndfile is a C library for reading and writing files containing sampled sound (such as MS Windows WAV and the Apple/SGI AIFF format) through one standard library interface.