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.
JackMixDesk is based on JackMiniMix and is a general purpose mixer for the Jack Audio Connection Kit. It has an OSC-based control interface, and a configurable number of mono/stereo inputs and pre/post sends/outputs that can be controlled by sending it OSC messages. There is LASH support and an XML config file.
As a plugin API, Frei0r's main emphasis is on simplicity, to round up the most common video effects into simple filters, sources, and mixers that can be controlled by parameters. Frei0r plugins can be shared by many host applications, avoiding duplicate efforts by different projects. Frei0r is not meant as a competing standard to more ambitious efforts trying to satisfy the needs of many different applications and more complex effects, as it doesn't provides things like an extensive parameter mechanism or event handling.
BpmDj is a program that can be used by a DJ. It plays MP3 and Ogg files. It has a fully automatic BPM counter. It can determine the sound color. It has a full fledged Qt based interface. It will help you manage a large amount of songs. It can help in creating playlists and has proven to be very robust. The program also allows offline automatic mixing and contains a wavelet based beat graph analyzer to visualize audio tracks.
Mixxx is software for DJs that provides everything needed to create live mixes. It allows you to beatmatch songs and crossfade them together, like you would with turntables and a mixer. It runs without any extra hardware, and offers a wide range of advanced features including comprehensive MIDI controller and vinyl control support. To obtain the lowest latency and highest responsiveness, it uses hardware video acceleration and takes advantage of multi-core CPUs.
irrKlang is a high level 2D and 3D cross platform sound engine and audio library that plays WAV, MP3, OGG, MOD, XM, IT, S3M, and other file formats. It can be used by C++ and all .NET languages (C#, Visual Basic.NET, etc.). It has all of the features common to low-level audio libraries as well as lots of useful features like a sophisticated streaming engine, extendable audio reading, single and multi-threading modes, 3D audio emulation for low-end hardware, a plugin system, multiple rolloff models, sound effects, and more. All of these can be accessed via an extremely simple API using an object oriented design.