How CD Pregaps Gained Their Hidden Track Superpowers

One less-secretive way I've seen pregaps used is for live recordings.

The crowd noise betwixt songs can be contained in a pregap, so that it is only ever heard when listening to the album straight-through (instead of in shuffle or track-program mode).

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Another fun feature of audio CDs is indexes.

A disc can have 99 tracks, and each track can have some pregap (including track 1, as the article discusses). And each of these 99 tracks can be further subdivided with 99 index markers.

This gives a CD the theoretical ability to have 9,801 selectable audio segments.

Although realistically, I've only owned a couple of CD players that even displayed index numbers and exactly one CD player (a Carver TL-3300) that allowed a person to seek to a given index number within a track.

(And I've only known one CD to actually make use of indexes in any useful manner, which was a sound effects CD from the early 1980s that had a lot more than 99 sounds on it -- all organized by tracks, and sub-organized by index marks. I just can't think of the name right now.)

Semi-related: "Minidisc" is an album by Gescom (who are really Autechre in disguise) released, as the name suggests, only on Minidisc, containing 88 tracks which are designed to be played on shuffle, because Minidisc, unlike CD or any other physical format, can be shuffled with no audible gap between tracks.

Each track is designed to segue into any other so the album is different every time you play it.

I was responsible for some of the first digital content ingestion for the world's record labels back in the late 90s, which was all based around trucks filled with retail CDs being fed into CD-ROM drives and an army of young folks grinding hundreds of track names into a database. (what happens when a truck full of East Asian CDs turns up? what about all those albums by Aphex Twin and Sigur Ros with untypeable names? https://www.treblezine.com/wp-content/uploads/2014/08/aphex-... )

I love these hidden tracks to death, especially the two hidden pregap tracks on Ash's first album, but they caused me unending pain and suffering.

Not only are they an absolute nightmare to rip, often with more than one song per track (so the WAVs have to be edited), the names of the songs are often totally unknown, even to the record labels. What do you even number the things in the metadata?

Added to that, you nearly always didn't even know they were there, so the negative numbered tracks would fail to get ripped and all the other ones in between or at the end would get ripped in weird ways and confuse all the data folk.

https://www.discogs.com/release/984235-Ash-1977

"Help, computer."

One memorable album using this was Queens of the Stone Age’s Songs for the Deaf. If you rewound from the start of the first track you got 90 seconds of strange sounding (but tuneful) rumbles and bleeps and bloops.

When I looked it up online I found out it was called “The Real Song for the Deaf”. It was literally a song for deaf people, the idea was that if they turned it up enough they’d be able to hear the vibrations forming a song.

For those interested to listen via a more accessible method: https://www.youtube.com/watch?v=XEU01LrnWng

I read this whole thing twice and I now know what pregaps are and the history but still have no idea why people would put them on a CD or why they’re useful for hidden tracks.

I remember my friend accidentally found the negative track on a CD and called me up out of breath like aliens just landed. I think it was one of the early AFI albums.We spent the whole weekend checking for negative tracks on every CD we could find.

The negatives between songs were also pretty cool sometimes, Mediocre Generica by Leftover Crack makes very good use of them. Listening to it over streaming or even mp3s ruins the effect, unless someone captured the entire album as one file.

I've been using https://github.com/whipper-team/whipper to digitize CD's, and it supports identifying Hidden Track One Audio (HTOA) when it exists and is not blank.

Add in MusicBrainz Picard and Navidrome and you have a really nice solution.

This specification anomaly sounds like the polycarbonate equivalent of vinyl's multiple-groove capability. [0]

I'd first heard of this for a Monty Python record (wikipedia notes this is in fact the most famous use case) but checked to see if people went for >2 grooves, and seemingly they did. I expect the casting for the pressing was horrendously expensive, which is why it didn't happen an awful lot.

I suppose both mediums shared the less-well-hidden feature where a long silence separated the penultimate from the ultimate track.

[0] https://en.wikipedia.org/wiki/Multisided_record

I recall a CD of mine had hidden audio before track one circa 1997, a coffee table jungle breakbeat on a Symphonic Black Metal album:

https://www.discogs.com/release/373044-Arcturus-La-Masquerad...

Also on the topic of trying to push the compact disc to its limits a Grindcore group who had a bonus track where "All efforts were made to exceed typical limitations of 16 bit linear digital technology compression, limiting, and equalization curves have been created to deliver maximum gain structure"

https://www.discogs.com/release/4305023-Exit-13-Ethos-Musick

I had a period of bad luck in my youth where I believed all these new enhanced CD's and shaped CD's were damaging the tracking of the lens on my CD player so I gave Exit-13 a swerve and started to listen to safer music ;)

Things like CD's with their large number of partly-compatible extensions shoehorned in remind me that whenever one is writing a specification, one should make sure that every combination of bits/bytes is either valid with defined behaviour, or invalid.

The one exception is a field for "extensions", which should have some bits for 'compatible' extensions (ie. there will be extra data ignored by readers which don't understand them), and other bits for 'incompatible' extensions (ie. you have put a DVD into a CD player).

I had a Rammstein ablum, that if you rewound before track 1 there was a black box audio recording of a plane crash were everyone died. It was pretty macabre. I think the CD cover was like a plane's black box if I remember correctly.

One compact disc extension I remember well is CD+G. It was pretty wild plugging an Information Society CD into a CDTV and watching the (admittedly crappy) graphics while you listened to music and samples of Leonard Nimoy and DeForest Kelley...

I remember discovering “hidden tracks” on the Beastie Boys intergalactic album with my cousins… we were like what on earth is happening as the CD player display glitched out and played this stuff we hadn’t heard.

If you are interested in this topic, locked grooves may also interest you.

https://en.wikipedia.org/wiki/Unusual_types_of_gramophone_re...

"Korn - Follow The Leader" (1998) album started on track 13.

https://www.discogs.com/release/369188-Korn-Follow-The-Leade...

that whole article went into a lot of detail about the history of pregaps, but never says what was actually put on the pregap

The domain name is how I felt after trying to read the article.

Abusing the standard to put songs in gaps was such a bad idea.

I have no idea how they got a patent for such a thing and, even worse, anyone ever did it on actual commercial discs.

In the age of attention deficit infused dopamine—-who has the time for an Easter egg?

Instead, engineers and product managers, slow roll quirkiness on social media.

What's the "A.C." band?

This inspired me to read up on the low-level details of CD structure. I'm curious if anybody scanned an entire CD and shared the results, so that we could work with a raw image of disc that contains all its quirks, as opposed to the typical .iso format?

IIRC Blink 182 had a hidden track "Fuck a Dog" on their album Take Off Your Pants and Jacket.