A disc jockey, also known as DJ, is a person who selects and plays recorded music for an audience. Originally, "disc" (s

ometimes spelled "disk", although this is now uncommon) referred to phonograph records, not the later Compact Discs. Today, the term includes all forms of music playback, no matter the medium.

There are several types of disc jockeys. Radio DJs or radio personalities introduce and play music that is broadcast on AM, FM, shortwave, digital, or internet radio stations. Club DJs select and play music in bars, nightclubs, or discothèques, or at parties or raves, or even in stadiums. Hip hop disc jockeys select and play music using multiple turntables, often to back up one or more MCs, and they may also do turntable scratching to create percussive sounds. In reggae, the DJ (deejay) is a vocalist who raps, "toasts", or chats over pre-recorded rhythm tracks while the individual choosing and playing them is referred to as a selector.[1] Mobile DJs travel with portable sound systems and play record.

Club DJ equipment may consist of:

§ Sound recordings in a DJ's preferred medium (for example, vinyl records, Compact Discs, computer media files, etc.);

§ A combination of two devices (or only one, if playback is digital) to play sound recordings, for alternating back and forth to create a continuous playback of music (for example, record players, Compact Disc players, computer media players such as an MP3 player, etc.);

§ A multiple Sequencer which can mix MIDI tracks with Digital Audio;

§ A sound system for amplification or broadcasting of the recordings (for example, portable audio system, PA system) or a radio broadcasting system;

§ A DJ mixer, which is an (usually 2- or 4-channel) audio mixer usually equipped with a crossfader used to smoothly go from one song to another, using two or more playback devices;

§ Headphones, used to listen to one recording while the other recording is being played to the audience, or to listen to both recordings simultaneously; and

§ Optionally, a microphone, so that the DJ can introduce songs and speak to the audiences.

Other equipment could or can be added to the basic DJ setup (above), providing unique sound manipulations. Such devices include, but are not limited to:

§ Electronic effects units (delay, reverb, octave, equalizer, chorus, etc.). Some club DJs use a subharmonic synthesizer effect which either doubles low frequencies with energy added an octave lower or synthesizes harmonics such that the impression of a very low bass sound is added to the mix.

§ A computerised performance system, which can be used with vinyl emulation software to manipulate digital files on the computer in real time.

§ Multi-stylus headshells, which allow a DJ to play different grooves of the same record at the same time.

§ Special DJ digital controller hardware can manipulate digital files on a PC or laptop;

§ Samplers, sequencers, electronic musical keyboards (synthesizers), or drum machines.

§ A Midi Controller used to trigger different aspects of DJ Software, such as Serato Scratch Live, Virtual Dj, and Traktor.

Computer DJ

A Computer DJ is defined as a DJ who uses a computer or laptop to play digital music encoded audio files, to a public crowd. Originally due to file size storage issues this was usually usinglossy codec files (e.g. .mp3/.aac), however as drive space increased, this improved to using original uncompressed PCM files (e.g. .wav/.aiff) which do not offer support for metadata, hence why latterly the metadata included and smaller file-sized lossless codec files (e.g. .flac/.m4a, ALAC) are used.

As well as a laptop or computer, MIDI controllers are also used to provide a more tactile, and useful interface for control of DJ Software by providing physical controls similar to those of record decks or CDJs and DJ mixers. External Hard Disk Drives and Audio Interfaces (Sound Cards) are also commonly utilized. By using a sound card with multiple stereo outputs, or two sound cards, a Computer DJ can use a conventional DJ mixer by routing one software deck out of one sound card into one channel of the mixer, and likewise for the other deck. Some DJ software packages allow a single stereo channel to be broken into two mono outputs which correspond to two player decks.

Most DJ Software allows the integration and manipulation of external audio inputs, and this has encouraged many DJs who have previously only used Vinyl or CDs to integrate a laptop into their setup. Computer controllers can also be plugged in via a USB port for the convenience of their moving controls like knobs and sliding buttons in order to control the software in realtime. The setup allows for a single audio output from the sound card to the amplifier/powered speakers. The controller is beneficial also with scratching, smoother pitch & crossfading adjustments, and overall ease of performing functions as opposed to mouse-controlled DJ software operation.

Computerized Performance System - a CPS can be programmed to manipulate audio and/or video, symbols, perform complex and repetitive mixing procedures quickly, precisely and reliably for recorded or live performance. CPS systems don't jump like traditional Compact discs.

in 1998, manufacturers joined with computer DJing pioneers to offer professional endorsements, the first being Professor Jam (aka William P. Rader), who went on to develop the industry's first dedicated computer DJ convention and learning program, the "CPS (Computerized Performance System) DJ Summit". Computer DJ'ing has since become popular with many professional electronic artists, though there is still considerable debate as whether or not the dependence on a computer in performance renders it ineligible for inclusion in the humanities. Producers likeMagnetic Man, deadmau5 and Daft Punk use computer technology.

DJ digital controller

DJ digital controllers are MIDI controllers or USB-to-analog devices used for controlling computer based DJ software, installed on a PC or laptop.

Operation

The DJ digital controllers aim to emulate the traditional mixer/turntable/CD turntable set up. Most controllers come with shuttle jog dials that mimic turntable control of an audio file, though with slightly less accuracy.

The use of DJ digital controllers with DJ software allow for a more mobile and compact system. Usually, the use of a DJ digital controller lets the DJ not have to transport more expensive, fragile, heavier, analog equipment. With the use of the controllers there is no need to use CDs or records. This is particularly beneficial to Mobile disc jockeys who are increasingly using computer based DJ set ups for this particular reason.

A problem with controllers had been their latency; that is, the time between manipulating the jog shuttle controllers and the effect on the audio file. However, this does vary with computer speed, sound card latency and MIDI latency. By either changing configuration settings or upgrading hardware, latency problems can often be easily resolved. Currently, with the newer PCs and Macs, better software and newer controllers, latency has become negligible if not non-existent.

An advantage of controllers is that the processing power of the computer can be used to manipulate the sound, giving a wide range of effects and sampling options. Native Instruments Traktorsoftware was among the first DJ applications to take advantage of this. Also, controllers are often platform-independent, allowing for highly customized setups. A DJ can choose and configure the software and use a variety of controllers with it. Some DJs even use two or more controllers for different applications during a set.

Software

Some notable DJ Software:

§ Ableton Live.

§ Blaze.

§ Serato Scratch Live.

§ Serato Itch.

§ Traktor Scratch.

§ Transitions DJ.

§ Deckadance.

§ djay (software).

§ DJ Mixer (Software) for iPad, iPod Touch and iPhone by Musicsoft Arts, LLC.

§ DJ Music Mixer by Program4Pc Inc.

§ DSS DJ by MyXOFT.

§ DUBturbo by DUBturbo.

§ Final Scratch by N2IT.

§ FL Studio, formerly known as FruityLoops.

§ MegaSeg

§ Mixed In Key

§ Mixmeister.

§ Mixxx.

§ OtsAV by Ots Labs.

§ PCDJ, also distributed as DJ Decks.

§ Reason (software) by Propellerhead.

§ Torq (Software) by M-Audio.

§ Touch DJ for iPad, iPod Touch and iPhone by Amidio Inc.

§ Live Touch XJ for Android Honeycomb 3.0 tablet by Ematrade.

§ Logic Pro by Apple.

§ UltraMixer

§ Virtual DJ (VDJ), also distributed as Numark CUE.

§ Visual Discomix, also known as VisualDiscoMix (VDMX).

Note: Some of these software are not commonly used for live performances, but are used as digital audio workstations (DAW) for the modification/creation of audio files to help mix, edit, and sample audio for live performances. Namely, FL Studio and Logic pro.