The Advanced Linux Sound Architecture is composed of several parts. The first is a fully modularized sound driver which supports module autoloading, devfs, isapnp autoconfiguration, and gives complete access to analog audio, digital audio, control, mixer, synthesizer, DSP, MIDI, and timer components of audio hardware. It also includes a fully-featured kernel-level sequencer, a full compatibility layer for OSS/Free applications, an object-oriented C library which covers and enhances the ALSA kernel driver functionality for applications (client/server, plugins, PCM sharing/multiplexing, PCM metering, etc.), an interactive configuration program for the driver, and some simple utilities for basic management.
somaplayer is music player for MP3, Ogg, wav, audio CDs, MP3 streams, and Ogg streams. It is able to use the appropriate sound drivers or demons or to stream directly to an Icecast server (Icecast2 or SHOUTcast) or to encode in MP3 and Ogg Vorbis. It also acts as a sound daemon that is able to accept connections from other somaplayers or any other sound player (xmms, mpg123, and others) thanks to a special wrapper.
jMax is a visual programming environment for building interactive real-time musical and multimedia applications by allowing the user to interactively design dataflow circuits. The basic data types that can go through are integers, symbols, lists, etc. It is an event-driven system and has been used for MIDI processing. A second part of the system (DSP) allows a continuous signal to flow through a circuit, which is most useful for PCM sound (ie. microphone, sound files, etc.). The system is extensible by using shared libraries, you may add data processor types, data types, GUI elements, device types, and more. Data processors may also be designed as circuits and reused.
GtkGEP turns your computer into a realtime effects processor. You can plug your guitar into the computer and play with cool distortion effects, for example. It has a modular plugin structure, with standard plugins including distortion, overdrive, delay, reverb, equalizers, and a flanger. It works in 16-bit resolution, in mono mode, and with frequencies from 11khz to 44khz. The sound quality is very good.