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How CD pregaps gained their hidden track superpowers

235 points by shortformblog 2y ago

MOARDONGZPLZ 2y ago
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.
- dylan604 2y ago
  Oh good, so I'm not the only one that thought the article failed to actually state what the superpower was. Some lame ass patent was granted?
- monocasa 2y ago
  Basically cd audio tracks have a base sector and a start specified. That allows sectors representing audio before timestamp 0:00 to be represented the track. The reason for this originally was probably to allow the drive to get synchronized before the track started. Enterprising cd masterers put actual hidden audio data in that area which would allow you on some CD players to rewind past 0:00 and then play the hidden audio at the negative timestamp.
  - crazygringo 2y ago
    How much hidden audio could be stored? Was it limited to something negligible like a couple of seconds? Or could you store a whole five-minute recording in there or something?
    - boomboomsubban 2y ago
      There doesn't seem to be a limit, this https://en.wikipedia.org/wiki/List_of_albums_with_tracks_hidden_in_the_pregap https://en.wikipedia.org/wiki/List_of_albums_with_tracks_hid... mentions a 27 minute live recording.
      - jvan 2y ago
        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!
        ChrisArchitect 2y ago
        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)
      - croes 2y ago
        I guess the limit is some milliseconds short of 74 minutes.
  - deleted 2y ago
    [deleted]
- add-sub-mul-div 2y ago
  As the article says its like an easter egg, putting a hidden song before the first track of a CD. If the song wasn't in the pregap it wouldn't be hidden. It's just for fun. (Sometimes songs can also be hidden in tracks at the end of the CD like 99, but that feels less mysterious.)
  - mattl 2y ago
    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.
    - add-sub-mul-div 2y ago
      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.
      - mattl 2y ago
        I think it tells you in the liner notes that you should use the shuffle button. My copy in the UK at the time didn’t have the individual tracks. Just one track.
      - ssl-3 2y ago
        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.)
    - gwbas1c 2y ago
      I remember getting surprised by one of those. I was at a friend's house and forgot to turn off the CD at the end. It was funny at first, but when every other CD I bought had one, it became tacky.
- mikepavone 2y ago
  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.
  - kevin_thibedeau 2y ago
    The key for a hidden track at the beginning is that players usually start playing track 1 from index mark 1 (1.1) rather than index 0 as with continuous play through all subsequent tracks. The lead-in area for 1.0 is a holdover from grooved phonorecordings never meant to be played. It's a way for the primitive hardware of early CD players to acquire the start of the data stream in a safe area that doesn't have to be faithfully reproduced. Some players permitted you to skip back from 1.1 to 1.0 to hear the lead-in as a hidden pseudo-track. Typically this was only possible with hardware index nav. buttons rather than the track nav. buttons, further obfuscating the presence of the hidden track. The other means of "hiding" tracks is to have a bunch of short silent tracks until you get to track 99 (inconvenient to reach on a player without numeric track entry) or to have a long section of silence starting on the last track from index 1.
    - crtasm 2y ago
      >Typically this was only possible with hardware index nav Holding the previous track button would "rewind" playback and get you into the pregap on all the CD players I remember using, but these would have been late 80s models onwards.
- barrkel 2y ago
  The writing is not good; I gave up part way through. It's weirdly elliptic and almost autistic in its focus on details and an almost complete absence of a big picture. It could do with some kind of proper context-setting introduction, at the very least.
  - WarOnPrivacy 2y ago
    This mirrors my experience. It's good content but I'd barely land on one splainer before being segueded into the next one. I kept thinking I missed the part they delved into hidden tracks.
  - nayuki 2y ago
    A CD audio frame is defined as exactly 1/75th of a second (588 samples per channel). I don't know why the article waffles around with these poor wordings (emphasis mine): > These albums all had a pregap of either 32 or 33 “frames,” with a frame representing a length of about 1/75th of a second, per Hydrogen Audio’s Wiki. > To offer a small correction to the original question now that we know we’re talking about 74 frames per second rather than 60 or 100 It's needlessly confusing and undermines my confidence of the entire article.
omar_alt 2y ago
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-Masquerade-Infernale 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 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 ;)
fortran77 2y ago
What's the "A.C." band?
- K7PJP 2y ago
  https://en.wikipedia.org/wiki/Anal_Cunt https://en.wikipedia.org/wiki/Anal_Cunt
zdw 2y ago
I've been using https://github.com/whipper-team/whipper 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.
- chuckufarley 2y ago
  Whipper user here also. If you've not yet encountered it, as it's not as prevalent in repos as Whipper, Cyanrip is always very much worth a look and has come on in leaps and bounds, with recent updates adding (non compliant) .cue sheet support.
dec0dedab0de 2y ago
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.
- Lammy 2y ago
  > I think it was one of the early AFI albums I wouldn't call it an “early” album but I found one of these (untitled 18-second intro) on AFI - DECEMBERUNDERGROUND: https://i.imgur.com/XAsFMSR.png https://i.imgur.com/XAsFMSR.png Some others I've run across in my CD collection include… — on Jonathan Katz - Caffeinated https://i.imgur.com/4ghQadv.jpeg https://i.imgur.com/4ghQadv.jpeg — the track "Every Time Is The Last Time" on Bloc Party's Silent Alarm https://i.imgur.com/knhbZhA.png https://i.imgur.com/knhbZhA.png — a kid606 remix hidden in the first track pregap of The Locust's eponymous https://i.imgur.com/sXVFrQI.jpeg https://i.imgur.com/sXVFrQI.jpeg — the "Theme of Coon" (aka Riki) on the third disc of the SaGa Frontier soundtrack https://i.imgur.com/CqTTqpV.png https://i.imgur.com/CqTTqpV.png > The negatives between songs were also pretty cool sometimes And one of these, the interlude at the end of “High Roller” on TCM's Vegas which is part of the pregap for “Comin' Back” https://i.imgur.com/G5PSCy3.jpeg https://i.imgur.com/G5PSCy3.jpeg
  - Elidrake24 2y ago
    Very Proud of Ya: https://en.m.wikipedia.org/wiki/List_of_albums_with_tracks_hidden_in_the_pregap https://en.m.wikipedia.org/wiki/List_of_albums_with_tracks_h...
  - dec0dedab0de 2y ago
    I wouldn't call it an “early” album but I found one of these (untitled 18-second intro) on AFI - DECEMBERUNDERGROUND I think it was answer that and stay fashionable. We all stopped listening to them when black sails came out, so if im right about it being AFI, it was one of the first 3 albums, or the all hallows EP.
exabrial 2y ago
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.
snvzz 2y ago
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.
- ssl-3 2y ago
  Why? Are easter eggs like this harmful to consumers or something?
  - snvzz 2y ago
    It's abusing the standard, which can break compliant implementations. Especially bad since most Audio CD players are opaque hardware without update-able firmware.
    - ssl-3 2y ago
      Has this been shown to be actually-problematic in the three decades since Willy Nelson's album contained a song in the pregap of track 1?
      - zarmin 2y ago
        of course not.
      - lampiaio 2y ago
        Yes, there's been a serious issue recently reported. Apparently, it has triggered bureaucrats on the internet who can't acknowledge something innocuous that's never caused any problem for decades.
        thelastparadise 2y ago
        Link?
        egypturnash 2y ago
afavour 2y ago
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 https://www.youtube.com/watch?v=XEU01LrnWng
- leonard-slass 2y ago
  I have the hardware and the CD. I did not know you could rewind to negative seconds of the first track. Thank you, you have made my day!
- mckn1ght 2y ago
  Same for 311’s Transistor. I remember accidentally doing it and wondering if I’d somehow distorted the fabric of spacetime. Took me a while to figure it out.
d332 2y ago
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?
- sho 2y ago
  Coming back to this, having read some of the (great!) replies, I'm going to go out on a limb and say that in theory, this sounds possible, and fun, but highly impractical. I'll assume that by "scan" you mean a high end "flatbed scanner" optical scan which would return a 2D bitmap. It's impractical because the resolution required to retrieve the data "flatbed scanner style" is comically high, perhaps 50k dpi, far beyond the capability of any commercial unit and well into scanning microscope territory. Sure, from my understanding, it looks technically possible. But it would be a very significant and costly project just to assemble the image in the first place. Even if you had that, the resulting file would be hilariously huge (something like 122GB), extremely difficult to work with, and you would be starting from scratch implementing some kind of visual pathfinding helical decoder to painstakingly unravel the linear coil of data the scan just sort of blatted into two dimensions. It's a cool idea. But it's comically, exponentially harder than just using the equipment as intended to just read the laser returns off the disk directly, into a far, far more easily dealt with format. I'm adding that CD scan to my list of things I'd like to do if I ever get really rich.
- ssl-3 2y ago
  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.
  - d332 2y ago
    But that's not my goal. I'd like to be able to observe every grove, the physical encoding of data, and see if I could implement decoding from scratch. First problem is though that I don't know how to get a microscopic image of the disc.
Jedd 2y ago
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 https://en.wikipedia.org/wiki/Multisided_record
- alanfalcon 2y ago
  This is supremely cool, thanks for sharing. I'm probably missing something obvious but why would the casting be any more expensive than any other pressing?
  - Jedd 2y ago
    Not terribly informed about the pressing process, but as I understand it, it is (or was) effectively a player-process in reverse. A needle creates the groove(s), replete with bumps for sound, in a not-quite-set (slightly soft) master disc - and I _speculate_ those follow a specific path defined by the mastering tool. In comparison, playback just drops the needle in the track, and it necessarily follows the extant spiral form. Making the master of a multi-groove record I'm assuming would require recalibration of the groove-defining mechanism (doubtless carefully designed for conventional layout), once for each of the grooves you want to make, ensuring they each stay within the boundaries defined by the previous grooves.
- caf 2y ago
  When I was very young, my parents had a game called 'wacky races' that was based on a multi-groove vinyl. It was a horse-racing game - I can't recall exactly how the gameplay worked, but the vinyl contained racing calls where the races would start the same way but the outcome would be somewhat random depending on which groove the needle ended up following.
  - 2y ago
ssl-3 2y ago
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.)
- cainxinth 2y ago
  > Broken was re-released as one CD in October 1992, having the bonus songs heard on tracks 98 and 99 respectively, without any visual notice except for the credits, and tracks 7–97 each containing one second of silence. https://en.wikipedia.org/wiki/Broken_(Nine_Inch_Nails_EP)#Packaging https://en.wikipedia.org/wiki/Broken_(Nine_Inch_Nails_EP)#Pa... Amarok (1990) by Mike Oldfield is a single hourlong track with 53 index marks. https://en.wikipedia.org/wiki/Amarok_(Mike_Oldfield_album)#Track_listing https://en.wikipedia.org/wiki/Amarok_(Mike_Oldfield_album)#T...
  - egypturnash 2y ago
    Broken was absolutely perfect to put into a multi-disc player along with TMBG's Apollo 18, which contains "Fingertips", a suite of 21 very short songs. Set it to shuffle songs from everything in the player, and enjoy your sonic whiplash
    - eyelidlessness 2y ago
      If you want sonic whiplash without so much effort, you can also listen to a Fantomas album in its original order.
indus 2y ago
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.
RiverCrochet 2y ago
If you are interested in this topic, locked grooves may also interest you. https://en.wikipedia.org/wiki/Unusual_types_of_gramophone_records https://en.wikipedia.org/wiki/Unusual_types_of_gramophone_re...
fnord77 2y ago
that whole article went into a lot of detail about the history of pregaps, but never says what was actually put on the pregap
qingcharles 2y ago
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-twin-syro-tracklist.png.webp 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 https://www.discogs.com/release/984235-Ash-1977 "Help, computer."
kstenerud 2y ago
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...
LeoPanthera 2y ago
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.
comprev 2y ago
"Korn - Follow The Leader" (1998) album started on track 13. https://www.discogs.com/release/369188-Korn-Follow-The-Leader https://www.discogs.com/release/369188-Korn-Follow-The-Leade...
Neil44 2y ago
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.
- 10729287 2y ago
  I’m not into this band but that could be related to this famous event : https://en.wikipedia.org/wiki/Ramstein_air_show_disaster https://en.wikipedia.org/wiki/Ramstein_air_show_disaster
  - hnbad 2y ago
    No, that's what they were named after. They released an epinomous song on their first album (Herzeleid) that played with the visual imagery of that disaster ("Rammstein - a human burns / Rammstein - the smell of meat in the air / Rammstein - a child dies / Rammstein - the sun is shining"). They apparently initially wanted to name the band Rammstein Flugschau ("Rammstein flight show") before shortening it to Rammstein. The difference in spelling was accidental but Rammstein is evocative (literally "ramming stone") so it stuck. The album the parent mentions is Reise, Reise, which is travel themed (in a broad sense of the word), the cover being styled after a black box (being bright orange of course). The flight recording in the pregap literally comes from a black box of a plane crash so that fits.
- Loughla 2y ago
  Reuse, Reise is the album. It was a Japanese aircraft crash. It was on every album but those released in Japan I'm pretty sure. It's mostly just scrambled alarms and some Japanese yelling. Without the context it's pretty hard to understand what you're listening to.
londons_explore 2y ago
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).
sziring 2y ago
The domain name is how I felt after trying to read the article.
deleted 2y ago
[deleted]
tombert 2y ago
IIRC Blink 182 had a hidden track "Fuck a Dog" on their album Take Off Your Pants and Jacket.
throwaway984393 2y ago
[dead]

235 points by shortformblog 2y ago

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.

dylan604 2y ago
Oh good, so I'm not the only one that thought the article failed to actually state what the superpower was. Some lame ass patent was granted?
monocasa 2y ago
Basically cd audio tracks have a base sector and a start specified. That allows sectors representing audio before timestamp 0:00 to be represented the track. The reason for this originally was probably to allow the drive to get synchronized before the track started. Enterprising cd masterers put actual hidden audio data in that area which would allow you on some CD players to rewind past 0:00 and then play the hidden audio at the negative timestamp.
- crazygringo 2y ago
  How much hidden audio could be stored? Was it limited to something negligible like a couple of seconds? Or could you store a whole five-minute recording in there or something?
  - boomboomsubban 2y ago
    There doesn't seem to be a limit, this https://en.wikipedia.org/wiki/List_of_albums_with_tracks_hidden_in_the_pregap https://en.wikipedia.org/wiki/List_of_albums_with_tracks_hid... mentions a 27 minute live recording.
    - jvan 2y ago
      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!
      - ChrisArchitect 2y ago
        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)
    - croes 2y ago
      I guess the limit is some milliseconds short of 74 minutes.
- deleted 2y ago
  [deleted]
add-sub-mul-div 2y ago
As the article says its like an easter egg, putting a hidden song before the first track of a CD. If the song wasn't in the pregap it wouldn't be hidden. It's just for fun. (Sometimes songs can also be hidden in tracks at the end of the CD like 99, but that feels less mysterious.)
- mattl 2y ago
  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.
  - add-sub-mul-div 2y ago
    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.
    - mattl 2y ago
      I think it tells you in the liner notes that you should use the shuffle button. My copy in the UK at the time didn’t have the individual tracks. Just one track.
    - ssl-3 2y ago
      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.)
  - gwbas1c 2y ago
    I remember getting surprised by one of those. I was at a friend's house and forgot to turn off the CD at the end. It was funny at first, but when every other CD I bought had one, it became tacky.
mikepavone 2y ago
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.
- kevin_thibedeau 2y ago
  The key for a hidden track at the beginning is that players usually start playing track 1 from index mark 1 (1.1) rather than index 0 as with continuous play through all subsequent tracks. The lead-in area for 1.0 is a holdover from grooved phonorecordings never meant to be played. It's a way for the primitive hardware of early CD players to acquire the start of the data stream in a safe area that doesn't have to be faithfully reproduced. Some players permitted you to skip back from 1.1 to 1.0 to hear the lead-in as a hidden pseudo-track. Typically this was only possible with hardware index nav. buttons rather than the track nav. buttons, further obfuscating the presence of the hidden track. The other means of "hiding" tracks is to have a bunch of short silent tracks until you get to track 99 (inconvenient to reach on a player without numeric track entry) or to have a long section of silence starting on the last track from index 1.
  - crtasm 2y ago
    >Typically this was only possible with hardware index nav Holding the previous track button would "rewind" playback and get you into the pregap on all the CD players I remember using, but these would have been late 80s models onwards.
barrkel 2y ago
The writing is not good; I gave up part way through. It's weirdly elliptic and almost autistic in its focus on details and an almost complete absence of a big picture. It could do with some kind of proper context-setting introduction, at the very least.
- WarOnPrivacy 2y ago
  This mirrors my experience. It's good content but I'd barely land on one splainer before being segueded into the next one. I kept thinking I missed the part they delved into hidden tracks.
- nayuki 2y ago
  A CD audio frame is defined as exactly 1/75th of a second (588 samples per channel). I don't know why the article waffles around with these poor wordings (emphasis mine): > These albums all had a pregap of either 32 or 33 “frames,” with a frame representing a length of about 1/75th of a second, per Hydrogen Audio’s Wiki. > To offer a small correction to the original question now that we know we’re talking about 74 frames per second rather than 60 or 100 It's needlessly confusing and undermines my confidence of the entire article.

omar_alt 2y ago

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-Masquerade-Infernale 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 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 ;)

fortran77 2y ago

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

K7PJP 2y ago
https://en.wikipedia.org/wiki/Anal_Cunt https://en.wikipedia.org/wiki/Anal_Cunt

zdw 2y ago

I've been using https://github.com/whipper-team/whipper 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.

chuckufarley 2y ago
Whipper user here also. If you've not yet encountered it, as it's not as prevalent in repos as Whipper, Cyanrip is always very much worth a look and has come on in leaps and bounds, with recent updates adding (non compliant) .cue sheet support.

dec0dedab0de 2y ago

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.

Lammy 2y ago
> I think it was one of the early AFI albums I wouldn't call it an “early” album but I found one of these (untitled 18-second intro) on AFI - DECEMBERUNDERGROUND: https://i.imgur.com/XAsFMSR.png https://i.imgur.com/XAsFMSR.png Some others I've run across in my CD collection include… — on Jonathan Katz - Caffeinated https://i.imgur.com/4ghQadv.jpeg https://i.imgur.com/4ghQadv.jpeg — the track "Every Time Is The Last Time" on Bloc Party's Silent Alarm https://i.imgur.com/knhbZhA.png https://i.imgur.com/knhbZhA.png — a kid606 remix hidden in the first track pregap of The Locust's eponymous https://i.imgur.com/sXVFrQI.jpeg https://i.imgur.com/sXVFrQI.jpeg — the "Theme of Coon" (aka Riki) on the third disc of the SaGa Frontier soundtrack https://i.imgur.com/CqTTqpV.png https://i.imgur.com/CqTTqpV.png > The negatives between songs were also pretty cool sometimes And one of these, the interlude at the end of “High Roller” on TCM's Vegas which is part of the pregap for “Comin' Back” https://i.imgur.com/G5PSCy3.jpeg https://i.imgur.com/G5PSCy3.jpeg
- Elidrake24 2y ago
  Very Proud of Ya: https://en.m.wikipedia.org/wiki/List_of_albums_with_tracks_hidden_in_the_pregap https://en.m.wikipedia.org/wiki/List_of_albums_with_tracks_h...
- dec0dedab0de 2y ago
  I wouldn't call it an “early” album but I found one of these (untitled 18-second intro) on AFI - DECEMBERUNDERGROUND I think it was answer that and stay fashionable. We all stopped listening to them when black sails came out, so if im right about it being AFI, it was one of the first 3 albums, or the all hallows EP.

exabrial 2y ago

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.

snvzz 2y ago

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.

ssl-3 2y ago
Why? Are easter eggs like this harmful to consumers or something?
- snvzz 2y ago
  It's abusing the standard, which can break compliant implementations. Especially bad since most Audio CD players are opaque hardware without update-able firmware.
  - ssl-3 2y ago
    Has this been shown to be actually-problematic in the three decades since Willy Nelson's album contained a song in the pregap of track 1?
    - zarmin 2y ago
      of course not.
    - lampiaio 2y ago
      Yes, there's been a serious issue recently reported. Apparently, it has triggered bureaucrats on the internet who can't acknowledge something innocuous that's never caused any problem for decades.
      - thelastparadise 2y ago
        Link?
        egypturnash 2y ago

afavour 2y ago

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 https://www.youtube.com/watch?v=XEU01LrnWng

leonard-slass 2y ago
I have the hardware and the CD. I did not know you could rewind to negative seconds of the first track. Thank you, you have made my day!
mckn1ght 2y ago
Same for 311’s Transistor. I remember accidentally doing it and wondering if I’d somehow distorted the fabric of spacetime. Took me a while to figure it out.

d332 2y ago

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?

sho 2y ago
Coming back to this, having read some of the (great!) replies, I'm going to go out on a limb and say that in theory, this sounds possible, and fun, but highly impractical. I'll assume that by "scan" you mean a high end "flatbed scanner" optical scan which would return a 2D bitmap. It's impractical because the resolution required to retrieve the data "flatbed scanner style" is comically high, perhaps 50k dpi, far beyond the capability of any commercial unit and well into scanning microscope territory. Sure, from my understanding, it looks technically possible. But it would be a very significant and costly project just to assemble the image in the first place. Even if you had that, the resulting file would be hilariously huge (something like 122GB), extremely difficult to work with, and you would be starting from scratch implementing some kind of visual pathfinding helical decoder to painstakingly unravel the linear coil of data the scan just sort of blatted into two dimensions. It's a cool idea. But it's comically, exponentially harder than just using the equipment as intended to just read the laser returns off the disk directly, into a far, far more easily dealt with format. I'm adding that CD scan to my list of things I'd like to do if I ever get really rich.
ssl-3 2y ago
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.
- d332 2y ago
  But that's not my goal. I'd like to be able to observe every grove, the physical encoding of data, and see if I could implement decoding from scratch. First problem is though that I don't know how to get a microscopic image of the disc.

Jedd 2y ago

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

alanfalcon 2y ago
This is supremely cool, thanks for sharing. I'm probably missing something obvious but why would the casting be any more expensive than any other pressing?
- Jedd 2y ago
  Not terribly informed about the pressing process, but as I understand it, it is (or was) effectively a player-process in reverse. A needle creates the groove(s), replete with bumps for sound, in a not-quite-set (slightly soft) master disc - and I _speculate_ those follow a specific path defined by the mastering tool. In comparison, playback just drops the needle in the track, and it necessarily follows the extant spiral form. Making the master of a multi-groove record I'm assuming would require recalibration of the groove-defining mechanism (doubtless carefully designed for conventional layout), once for each of the grooves you want to make, ensuring they each stay within the boundaries defined by the previous grooves.
caf 2y ago
When I was very young, my parents had a game called 'wacky races' that was based on a multi-groove vinyl. It was a horse-racing game - I can't recall exactly how the gameplay worked, but the vinyl contained racing calls where the races would start the same way but the outcome would be somewhat random depending on which groove the needle ended up following.
- 2y ago

ssl-3 2y ago

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.)

cainxinth 2y ago
> Broken was re-released as one CD in October 1992, having the bonus songs heard on tracks 98 and 99 respectively, without any visual notice except for the credits, and tracks 7–97 each containing one second of silence. https://en.wikipedia.org/wiki/Broken_(Nine_Inch_Nails_EP)#Packaging https://en.wikipedia.org/wiki/Broken_(Nine_Inch_Nails_EP)#Pa... Amarok (1990) by Mike Oldfield is a single hourlong track with 53 index marks. https://en.wikipedia.org/wiki/Amarok_(Mike_Oldfield_album)#Track_listing https://en.wikipedia.org/wiki/Amarok_(Mike_Oldfield_album)#T...
- egypturnash 2y ago
  Broken was absolutely perfect to put into a multi-disc player along with TMBG's Apollo 18, which contains "Fingertips", a suite of 21 very short songs. Set it to shuffle songs from everything in the player, and enjoy your sonic whiplash
  - eyelidlessness 2y ago
    If you want sonic whiplash without so much effort, you can also listen to a Fantomas album in its original order.

indus 2y ago

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.

RiverCrochet 2y ago

If you are interested in this topic, locked grooves may also interest you. https://en.wikipedia.org/wiki/Unusual_types_of_gramophone_records https://en.wikipedia.org/wiki/Unusual_types_of_gramophone_re...

fnord77 2y ago

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

qingcharles 2y ago

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-twin-syro-tracklist.png.webp 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 https://www.discogs.com/release/984235-Ash-1977 "Help, computer."

kstenerud 2y ago

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...

LeoPanthera 2y ago

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.

comprev 2y ago

"Korn - Follow The Leader" (1998) album started on track 13. https://www.discogs.com/release/369188-Korn-Follow-The-Leader https://www.discogs.com/release/369188-Korn-Follow-The-Leade...

Neil44 2y ago

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.

10729287 2y ago
I’m not into this band but that could be related to this famous event : https://en.wikipedia.org/wiki/Ramstein_air_show_disaster https://en.wikipedia.org/wiki/Ramstein_air_show_disaster
- hnbad 2y ago
  No, that's what they were named after. They released an epinomous song on their first album (Herzeleid) that played with the visual imagery of that disaster ("Rammstein - a human burns / Rammstein - the smell of meat in the air / Rammstein - a child dies / Rammstein - the sun is shining"). They apparently initially wanted to name the band Rammstein Flugschau ("Rammstein flight show") before shortening it to Rammstein. The difference in spelling was accidental but Rammstein is evocative (literally "ramming stone") so it stuck. The album the parent mentions is Reise, Reise, which is travel themed (in a broad sense of the word), the cover being styled after a black box (being bright orange of course). The flight recording in the pregap literally comes from a black box of a plane crash so that fits.
Loughla 2y ago
Reuse, Reise is the album. It was a Japanese aircraft crash. It was on every album but those released in Japan I'm pretty sure. It's mostly just scrambled alarms and some Japanese yelling. Without the context it's pretty hard to understand what you're listening to.

londons_explore 2y ago

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).

sziring 2y ago

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

deleted 2y ago

[deleted]

tombert 2y ago

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

throwaway984393 2y ago

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