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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

#31

Post by cainxinth »

ssl-3 wrote: post #29

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…

> 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)#Pa...

Amarok (1990) by Mike Oldfield is a single hourlong track with 53 index marks.

https://en.wikipedia.org/wiki/Amarok_(Mike_Oldfield_album)#T...

Re: How CD pregaps gained their hidden track superpowers

#32

Post by snvzz »

ssl-3 wrote: post #28
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?

It's abusing the standard, which can break compliant implementations.

Especially bad since most Audio CD players are opaque hardware without update-able firmware.

Re: How CD pregaps gained their hidden track superpowers

#33

Post by ssl-3 »

snvzz wrote: post #32
ssl-3 wrote: post #28

Earlier quoted context omitted.

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

It's abusing the standard, which can break compliant implementations. Especially bad since most Audio CD players are opaque hardware without update-able firmware.

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?

Re: How CD pregaps gained their hidden track superpowers

#35

Post by kevin_thibedeau »

ssl-3 wrote: post #29

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…

My personal CD ripping script is configured to leave all pregaps after track one at the end of the preceding track when splitting them out as individual files. It gets ripped in one DAO pass for guaranteed preservation of all samples when using gapless playback on live recordings. Track navigation then works just like a real CD without having to listen to an incongruous section of audio meant to link the previous track on sequential play or, even worse, missing it altogether.

I have a classical CD from the 80's with index marks for different movements within within the individual compositions represented by a handful of tracks. My understanding is that DG was the only publisher routinely using them. That required some manual intervention to convert the indices to separate tracks. Sony was pretty good about providing index nav. on their full size stereo players. At least until their perpetually cruddy remotes eventually failed.

Re: How CD pregaps gained their hidden track superpowers

#36

Post by d332 »

ssl-3 wrote: post #27
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.

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.

Re: How CD pregaps gained their hidden track superpowers

#37

Post by ssl-3 »

kevin_thibedeau wrote: post #35
ssl-3 wrote: post #29

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…

My personal CD ripping script is configured to leave all pregaps after track one at the end of the preceding track when splitting them out as individual files. It gets ripped in one DAO pass for guaranteed preservation of all samples when using gapless playback on live recordings. Track navigation then works just like a real CD without having to listen to an incongruous section of audio meant to link the previous tra…

That's probably the best way to do it, given common toolsets and players. I also rip pregaps as lead-outs (rather than the lead-ins that the structure may appear to suggest).

It's things like this that make me wish that we'd landed on on a good, popular way to store albums (with metadata!) instead of individual tracks -- or to at least reassemble individual tracks' files properly into whole albums without glitches and weirdness. (FLAC/cue can do some of this, but hardware player support is nearly nonexistant.)

I've been told that this is a stupid thing to want, and I want it anyway.

I'm old enough to remember listening to albums the whole way through by default since anything else would take extra steps, and perhaps fortunate-enough to have generally preferred listening to albums where that is a thing that is also worth doing intentionally.

(And yet, I am young enough to still be bitter about Lars killing Napster. My dissatisfaction is multifaceted.)

Re: How CD pregaps gained their hidden track superpowers

#39

Post by xxr »

nammi wrote: post #22
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

“Midnight Sun” at the end of Black Sails always gets me

Re: How CD pregaps gained their hidden track superpowers

#40

Post by kevin_thibedeau »

mikepavone wrote: post #30
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 s…

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.

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