apparently like this...
How do I put "hidden tracks" and negative indices on audio CDs?
(2001/06/26)
With a little searching you can find an audio CD that will cause your CD
player to show a negative track time when one track finishes and the next
begins. The negative sections are usually filled with silence, but some
rare discs will have material in them. If you seek directly to the track,
you don't see (or hear) the negative-time section.
The trick here is also described in section (3-14). You can specify the
start position of an audio track anywhere within the track. The start
position is at time index 00:00 (in minutes and seconds, MM:SS), so the
music before the start point is usually displayed with negative time values.
When you seek directly to a track, the player jumps to time index 00:00, but
when you play through from a previous track you hear the entire track.
When using CDRWIN-style cue sheets, the actual start of the track is at
"index 00", and the place where the player seeks to is "index 01". The
distance between the indices is called the pre-gap. The Red Book standard
requires that index 01 in track 01 be at least two seconds (150 sectors)
from the start of the CD.
You can specify additional index markers, but most CD players will simply
ignore them. Some CD-ROM games have tried to use the index markers as a
form of copy protection, because they won't get copied automatically by
many programs.
If you want to create your own discs with "hidden tracks", you need a program
that gives you full control over where the index markers go (CDRWIN is one
such program). Combine two (or more) tracks with an audio editor into a
single file. Specify the file as a single track in the cue sheet, set
"index 00" to time zero, and set "index 01" to a point right after the
"hidden" song finishes. There are other ways to approach this, but this
is probably the most straightforward.
It should be mentioned that the only truly "hidden" track is in track 1.
Most CD players will play the entire disc, from index 01 on track 1,
straight through to the end, so any tracks you try to "hide" in the
middle of the disc are simply difficult to seek to. The only way to play
audio tucked into the pre-gap in track 1 on most players is to hold down
the rewind button.
For more information about unusual audio CDs, see "CD Oddities" at
http://desolationvalley.com/wj/oddcd/index.shtml.
