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How CD pregaps gained their hidden track superpowers

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Re: How CD pregaps gained their hidden track superpowers

#21

Post by afavour »

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

Re: How CD pregaps gained their hidden track superpowers

#22

Post by nammi »

dec0dedab0de wrote: post #14

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 r…

AFI almost always had a "hidden" track after silence following the last track, I figured following the Misfits' tradition

Re: How CD pregaps gained their hidden track superpowers

#24

Post by ChrisArchitect »

jvan wrote: post #17
boomboomsubban wrote: post #16

Earlier quoted context omitted.

There doesn't seem to be a limit, this https://en.wikipedia.org/wiki/List_of_albums_with_tracks_hid... mentions a 27 minute live recording.

Incredible! Songs in the Key of X was the only album I ever knew to do this, and it wasn't even the first. I had no idea so many others did the same thing. Edit: Son of a *, I've had a copy of Sister Machine Gun's Burn for almost 30 years and never knew there was a hidden track!

Classic X-Files album is the one I think of too. And how they hinted to everyone that there even was a hidden track on the sleeve: "'0' is also a number". (and the technical fineprint about the disc possibly not being Redbook compliant)

Re: How CD pregaps gained their hidden track superpowers

#25

Post by Jedd »

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

Re: How CD pregaps gained their hidden track superpowers

#26

Post by ssl-3 »

add-sub-mul-div wrote: post #7
mattl wrote: post #6

Earlier quoted context omitted.

Sometimes CDs would have a long piece of silence at the end of the last song and then another song on the same track. Other CDs really experimented with the shuffle feature. They Might Be Giants’ Apollo 18 had a bunch of very short tracks that would usually play between songs when shuffle was used.

I had that CD and remember the short tracks but never thought of playing it on shuffle that way. I think it was nine inch nails' Broken EP that had the hidden tracks on 98/99 rather than after a long silence, but I could be wrong.

Broken was first released as a 2-disc set. It was still in a many-fold Digipak case, but also included was a 3" mini-CD that had Suck and Physical (You're So).

The regular-sized CD looked about identical to the 99-track version, but had only 6 tracks.

(It was expensive to do this, and was never intended for long-term production. Later versions were generally as you describe.)

Re: How CD pregaps gained their hidden track superpowers

#27

Post by ssl-3 »

d332 wrote: post #23

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?

Audio CDs were never ripped/transferred as ISO files. ISO-9660 is a filesystem that came years later, and Redbook audio CDs simply do not contain files.

If you want to look at the structure of a whole audio CD, then one way is to rip it with a decent tool (perhaps cdrdao or EAC) and generate a bin/cue file pair as an output.

Re: How CD pregaps gained their hidden track superpowers

#28

Post by ssl-3 »

snvzz wrote: post #18

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.

Why? Are easter eggs like this harmful to consumers or something?

Re: How CD pregaps gained their hidden track superpowers

#29

Post by ssl-3 »

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).

---

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.)

Re: How CD pregaps gained their hidden track superpowers

#30

Post by mikepavone »

MOARDONGZPLZ wrote: post #2

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.

An audio CD is mostly arranged like a single continuous recording. Tracks are added on top of this via the Q subcode channel that gives information about the current location and the ToC stored in the lead-in area (also using the Q subcode channel). In the ToC, each track will have one more indexes that points at a specific location on the disc by minute, second and "frame" (represents 1/75 of a second, basically a sector).

If a CD is properly following the Red Book standard, index 0 will point to a 2 second pre-gap of silentce and index 1 will point to the actual start of audio of the track (additional indices are allowed, but not common). The purpose of the pregap is to make life easier for less sophisticated players that aren't able to seek to a precise frame on the disc. They just have to be able to hit a 150 frame region. However, just because the standard says the pregap is supposed to be 2 seconds and silent doesn't mean it actually has to be. Players generally don't care and by the time the format was popular, even inexpensive players could seek precisely. This allows you to stick audio data before a track that will be skipped by the player when it's trying to seek to that track. If you stick it before track 01, it will be skipped even when just playing the disc through unless you rewind.

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