Pregap

The pregap on a Red Book audio CD is the portion of the audio track that precedes "index 01" for a given track in the table of contents (TOC). The pregap ("index 00") is typically two seconds long and usually, but not always, contains silence. Popular uses for having the pregap contain audio are live CDs, track interludes, and hidden songs in the pregap of the first track (detailed below).

Unconventional uses of the pregap

Computer data in pregap

The pregap was used to hide computer data, tricking computers into detecting a data track whereas conventional CD players would continue to see the CD as an audio CD.

This method was quickly made obsolete in late 1996 when an update to Windows 95 in driver SCSI1HLP.VXD made the pregap track inaccessible. It is unclear whether or not this change in Microsoft Windows' behavior was intentional: for instance, it may have been intended to steer developers away from the pregap method and encourage what became the Blue Book specification "CD Extra" format.

Hidden audio tracks

On certain CDs such as the "Songs for the Deaf" by Queens of the Stone Age, the pregap contains a hidden track. The track is truly hidden in the sense that most conventional standalone players and software CD players will not see it. Such CDs with an unusually long pregap before the first song can be detected by using EAC, which will highlight the first song in red.

Such hidden tracks can be played by playing the first song and "rewinding" (more accurately, seeking in reverse) until the actual start of the whole CD audio track.

Not all CD drives can properly extract such hidden tracks, using audio extraction software like Exact Audio Copy. Some drives will report errors when reading these tracks, some will seem to extract them properly, but the extracted file will only contain silence.

Albums with tracks hidden in the pregap

; 311: "Transistor" - "Transistor Intro"; A.C.T: "Last Epic" - hidden orchestral introduction; Adventures in Stereo: "Monomania"; AFI: "Decemberunderground" - hidden introduction:"Very Proud of Ya" - "No Dave Party" ; Agoraphobic Nosebleed:"Altered States of America" "100-song 3" Mini-CD/10" - Features a 1 minute, 45 second song entitled "Wonder Drug Wonderland" when track 1 is "rewound" . Effectively making a 100-song release, although the last track on the album is labeled "99" in all regular cd players. ; Alcazar: "Alcazarized" - "Dance With The DJ" (On the first edition of the album, released in Sweden); The Aliens: "Astronomy For Dogs" - Untitled hidden track in the pregap; Anal Cunt: "Morbid Florist" - Cover version of the Doors' "Hello, I Love You."; Apollo Up!: "Light the End and Burn it Through" - "Roken Is Dodeljik", a re-recording of an instrumental track from their Demonstration Recording EP; Arcturus: "La Masquerade Infernale" - Untitled hidden track; Armor for Sleep: "What to Do When You Are Dead" - A hidden suicide note ; Art Brut: "Bang Bang Rock & Roll" - "Subliminal Desire for Adventure"; Die Ärzte: "13" - "Lady" in the pregap of "Punk ist...":"Geräusch" - "Hände innen" in the pregap of "Als ich den Punk erfand...":"Jazz ist anders" Bonus EP - "Nimm es wie ein Mann" in the pregap of "Wir sind die Besten"; Ash: "1977 (early copies)"
#"Jack Names the Planets"
#"Don't Know"; Autechre: "EP7" - (untitled track); Beastie Boys: "Hello Nasty" - "El Rey y Yo" (not on all editions); Béla Fleck and the Flecktones: "Little Worlds" - Yankees outfielder Bernie Williams and David St. Hubbins of Spinal Tap, stuck in traffic and flipping through different radio stations. The songs they hear are songs from the album played in different styles and on different instruments.; Ben Folds Five: "Whatever and Ever Amen" - message by Ben Folds about Ben Folds "(only on re-masters)"; Better Than Ezra: "Friction, Baby" - (untitled track); Billy Bauer: "Plectrist"
#"Lover Come Back To Me" (incomplete take 1)
#"Lover Come Back To Me" (incomplete take 2); Blind Melon: "Soup" - "Hello Goodbye"; Blink-182: "Blink-182" - "Stockholm Syndrome Dialog"; Bloc Party: "Silent Alarm" - "Every Time Is The Last Time"; Blur: "Think Tank" - "Me, White Noise"; Boo Radleys: "Kingsize" - "Tranquillo"; Brand New: "The Devil and God Are Raging Inside Me" - Overlapping phone messages; Calexico: "Feast Of Wire" - (unknown title); Camouflage: "Sensor" - "Sensor Intro" - (0:35) - just some noises; Camouflage: "Relocated" - "Relocated Intro" - (1:21) - based on track "Bitter Taste" with words "I've got a name for you... Relocated"; Carina Round: "Slow Motion Addict" - "Same Girlfriend"; Clearlake: "Cedars" - "Sounds Of Clearlake" - 9 minutes of music/sound clips; Course of Empire: "Initiation" - "Running Man"; Criteria: "En Garde" (2003) - song by Team Rigge ; The Czars: "The Ugly People vs. The Beautiful People" - "Top Breed"; Dashboard Confessional: "Dusk and Summer"
#"Write It Out"
#"Vindicated"; Damien Rice : "9" - "9 Crimes" (Demo); David Ford: "I Sincerely Apologise For All The Trouble I've Caused" - "This Is Not Desire"; David Gray: "White Ladder" - "I Can't Get Through To Myself"; Diamond Rio: "IV" - Various earlier hits mixed with sound effects; Evanescence: "Origin" - A humorous outtake from the song "Anywhere"; Fair to Midland: "Fables From A Mayfly" - "Tibet"; Farin Urlaub: "Am Ende der Sonne" - "Noch einmal" in the pregap; Five Iron Frenzy: "All the Hype That Money Can Buy" (2000) - The 3-second song "What's Up?"; Frenzal Rhomb: "Shut Your Mouth" - "Baby Won't You Hold Me In Your Arm"; The Gathering:"Black Light District" - "Over You":"Souvenirs" - "Telson"; Goldie Lookin Chain: "Safe As Fuck" - "Bedsit"; Harvey Milk: "The Kelly Sessions" - "My Broken Heart Will Never Mend" (appears first on the album's track listing, but not described as a hidden track, thus resulting in much subsequent confusion); Hayden: "Skyscraper National Park" - "Mingus" (only present on the Canadian version); Head of Femur: "Ringodom or Proctor" - Untitled hidden track (glockenspiel and soft voice); Hilltop Hoods: "Left Foot, Right Foot" - "Afternoon Group Session":"The Calling" - "Stay The Fuck Away Because I Spilt When I'm Talking": "The Hard Road" - Untitled hidden track; Hot Club de Paris: "Drop It 'Til It Pops" - "Welcome to the Hot Club de Paris" (a capella); Hoodoo Gurus: "Blue Cave"; Hybrid:"Morning Sci-Fi" - "Lights go down Knives come out":"I Choose Noise" - "Everything is Brand New"; I Am Kloot: "I Am Kloot" - Deep Blue Sea; I Monster: "Neveroddoreven" - Cells; Jack Planck: "To Hell With You I'll Make My Own People" - "Fuck You"; James Brown: "Live At The Apollo Vol. 2 (Deluxe Edition)" - Radio DJ (and concert MC) Frankie Crocker talks to the crowd with a comedian for about four minutes before the show begins.; Jebediah: "Of Someday Shambles" - "Big Beer Wall"; Kamelot: "The Black Halo" - A short non-musical intro to the album.; Kenji Ito: "SaGa Frontier 1 - Original Soundtrack" - Disc 3: "Coon's Theme"; KULT: "Poligono Industrial" - "Kasta pianistów"; Kylie Minogue: "Light Years" - "Password"; Lamb::"Fear of Fours" - "Lullaby" (instrumental):"" - "Wonder" (instrumental version); Larrikin Love: "The Freedom Spark" - "It Explodes"; Less Than Jake: "Losing Streak" - banter spoken by former band mascot "Howie J. Reynolds", an elderly Gainesville local; Lewis Black: "The Carnegie Hall Performance (disc 1)" - (untitled Track); Lit: "A Place in the Sun" - (untitled Track); Look Down: "24/7 Dance Force" - Untitled; Luke Haines: "Das Capital" - "overture"; Lucy Kaplansky: "Flesh and Bone" - I've Just Seen A Face; Ludo: "You're Awful, I Love You" - Goodbye Bear; Mae: "Singularity" - Last Transmission: Part I; Matthew Parmenter: "Horror Express" - "Making Music"; Maxwell: "Embrya" - Gestation: Mythos with various voices and watery sound effects; Mayday: "Old Blood"
#"Domes/Doma/Dominarum Arcana/Döm"
#"Rebirthing"; Mayhem: "Grand Declaration of War" - "Completion in Science of Agony (Part II of II)"; McFly: "Room on the Third Floor" - "Get Over You"; Melt-Banana: "Charlie" - "Neat Neat Neat" (Originally by The Damned); Miocene: "Cellular Memory EP" - instrumental jam; Moneen: "The Red Tree" - hidden introduction; Mono Puff: "It's Fun to Steal" - (untitled track); The Music: "The Music (Limited Edition CD)" - "New Instrumental"; Ms. Dynamite: "A Little Deeper" - "Get Up, Stand Up"; Muse: "Hullabaloo CD 2" - "What's He Building", a poem read by Tom Waits; The Never: "Antarctica" - only confirmed on promotional version of CD; Nobuo Uematsu: "Final Fantasy VII Reunion Tracks" - Karaoke version of "One-Winged Angel (Orchestra Version)".; Norma Jean: "O' God The Aftermath (Deluxe Edition)" - an instrumental jam before the first track starts; Oceansize: "Everyone Into Position" - "Emp(irical)error"; The Offspring: "Americana" - "Pretty Fly (Reprise)" "(some versions)"; Opeth: "Ghost Reveries" - "Reverie"; Osdorp Posse: "Geendagsvlieg" - "Sleur"; Protest the Hero: "Fortress"; Public Enemy: "Muse Sick-n-Hour Mess Age" (1994) - "Ferocious Soul" (Drum track with Chuck D ranting about the state of Hip-Hop and the impending negative criticism the album is going to receive- which coincidently it did.); Queens of the Stone Age: "Songs for the Deaf" - "The Real Song For The Deaf"; Rammstein:"Live Aus Berlin" - "(Audience cheering)":"Reise, Reise" - "(Fragment of the flight recorder of a Japanese Boeing 747 disaster.)"; The Red Shore:"Salvaging What's Left"; Relient K: "Mmhmm" - "Mmhmm"; Resin Dogs: "Grand Theft Audio" -; Sanctifica: "Negative B" (2002) - 9min 20sec of hidden content (band members talking?); Sarah Masen: "The Dreamlife of Angels" (2001) - "Longing Unknown"; Satyricon: "Rebel Extravaganza" (1999) - "Untitled"; Simon Webbe: "Sanctuary" (2004) - "Pusherman" ; Sister Machine Gun: "Burn" (1995) - "Strange Days" (A cover of The Doors song); Skunk Anansie: "Stoosh" (1996) - (Untitled Track); Sly & Robbie: "Late Night Tales" - La Isla Bonita Cover by Sly & Robbie of Madonna track; Jimmy Smith: "Root Down" (2000) - Band and audience banter before the first song including Jimmy Smith telling the audience to be quiet.; SNFU: "FYULABA" (1996) - The sound of arguing before the first track between a band and an owner of a night club who accuses the band of trashing the dressing room. It is unclear if the band is actually SNFU or not.; Son of Dork: "Welcome to Loserville" - "Welcome To Loserville"; Soulwax: "Leave the Story Untold" (1996) - Untitled:"Much Against Everyone's Advice" (2000) - Untitled:"Any Minute Now" (2004) - Untitled:"Most of the Remixes" (2007) - Einstürzende Neubauten - Stella Maris (Soulwax Remix); Super Furry Animals:"Guerrilla" (1999) - "Citizen's Band":"Out Spaced" (1998) - "Spaced Out"; Tait: "Empty" (2001) - various random recordings; They Might Be Giants: "Factory Showroom" - "Token Back to Brooklyn"; tobyMac: "Welcome to Diverse City" - The "real" intro to the track "Burn For You"; Total Eclipse: "Access Denied" - "Cornered"; Tripping Daisy: "Time Capsule EP" - "Disgruntled Customer"; UNKLE: "Psyence Fiction" - "Intro (Optional)" (Uncredited intro featuring an audio collage of some of DJ Shadow's and James Lavelle's musical influences). This hidden audio is not on the US pressing, but can be found on UK and Japanese pressings. May be available on other pressings around the world.; Various Artists: "Songs in the Key of X (soundtrack from The X-Files)"
#"Time Jesum Transeuntum Et Non Riverentum (Dread the Passage of Jesus, For He Will Not Return)" by Nick Cave and the Dirty Three
#"The X-Files" theme by the Dirty Three; Various Artists: "Ego Trip's The Big Playback" - Interview with KRS-ONE; 2 Many DJs: "As Heard On Radio Soulwax Pt. 2" - "Can't Get You Out Of My Head" Remix of "Kylie Minogue"'s song; Vitalic: "OK Cowboy" (2005) - "One Million Dollar Studio"; The Wedding: "Polarity" (2007) - Outtakes from "Southside"; When: "The Lobster Boys" (2001) - Untitled Hidden Track; Winds: "Reflections of the I" - "untitled"; The Wombats: "" - Untitled (Talk and Drinking); Wintersleep: "Untitled" (2005) - "Spring"

Pregaps In CD-R Media OS support

Mac OS X:

Currently does not support more than a 2 second pre-gap in the first track under its CD burning utilities. Using a combination of Roxio's Toast and a custom .cue file can provide a way around this.

Windows XP:

*Exact Audio Copy provides the functionality to write to Index 0

Linux:

*cdrecord supports to write any kind of pregap
*cdrdao is currently being researched
*K3B, a frontend for several CD/DVD burning/ripping utilities, supports hiding the first track in the pregap of the second one.

ee also

*Hidden track
*List of albums containing a hidden track

External links

* [http://www.musicfan.com/ecd/formats.html History of Mixed-Mode CDs]
* [http://www.planbproductions.com/squirrelnutzippers/ziptech.html Technical Specifications] of the Squirrel Nut Zippers "Hot" ECD