In preparation for a performance, the VJ ("Video Jockey") collects videos, images, and music files on a computer, and then uses software, such as audiovisualizers, or a specialized VJ device, to play the music and to synchronously project the video and imagery for the audience.
There are a number of software packages for Linux users that provide tools for preparing or conducting VJ performances. One of the top free VJ software packages is Veejay, which functions as a video tracker and editing tool, as well as a realtime video sequencer and effects generator that allows you to use the keyboard for live control and interaction during a performance. Additionally, the dynamically generated production can be recorded for future use.
The software supports the codecs DV, MJPEG, MPNG, and Lossless JPEG, the containers rawDV, AVI, and Quicktime, and a variety of input devices, including USB webcams, DV1394, and TV capture cards. You can find a comprehensive list of features and the project web site.
The video editing software LiVES comes with an integrated VJ mode. LiVES is a mature and feature rich package for editing digital videos, creating real time video displays and imagery, and mixing visuals and music. It includes an RFX builder for creating effects and transitions, and can be extended through RFX plugins. LiVES handles most video formats and common audio formats.
VSXu is an open source programming environment for real-time music visualization using OpenGL-based, hardware-accelerated implementations. The software uses a modular architecture that enables you create and add your own extensions or visualization "presets". VSXu has essentially three modes of operation. (1) The VSXu Player is the basic music and sound visualizer for end users; (2) the VSXu Artiste is a tool for creating artistic visuals and videos; (3) the VSXu Server is the production environment for live performances.
Synaesthesia is a sophisticated program for generating graphical representations of music. It uses sound frequencies, location, and diffuseness to display detailed rapidly changing patterns and shapes of individual instruments and singers. The software can be used as a CD player and takes sound input from CDs or microphone, and can utilize stereo and surround sound information.
Amarok is a popular media player primary developed for managing and playing song collections. It supports a variety of sound visualization packages through its plug-in system.
VLC is a mature, cross-platform media player that provides robust support for a wide range of file formats and codecs. As a music player it offers visualizations comprised of colorful geometric shapes and dynamic imagery synchronized with the sound. The visualization menu options include Spectrometer, Scope, Spectrum, VU Meter, and Goom.