Extract hidden CD audio

On 2004-04-17, nomis wrote:
> They Might Be Giants put out a cd a few years ago, "Factory Showroom",
> where they included a hidden track before the album began proper.
>
> If you go to Track 1 on your cd-player and press REWIND you can listen
> to it. If memory serves correctly, the way they did this was by placing
> the audio information into Track 0

I have a few cds like this. In all cases, the trick is to use index
0, the so-called pre-gap, of track 1. Usually the pre-gap of any
given track has no data and is only used for inter-track silence,
typical for 2-3 seconds. In this case the pre-gap contains music, of
arbitrary length.

As for how you can extract this data, I don't know. I just tried
playing with cdda2wav and it doesn't seem to be willing to extract
index 0. The only other possibility I can think of is to use cdrdao
to read the entire cd, then adjust the table-of-contents (toc) file so
that the START of track 0 is 00:00:00, then burn the data using the
edited toc file to a cd-r. In theory the resulting cd-r should then
include the hidden track music as part of track 1 proper. I haven't
actually tried this though.

On 2004-04-17, noman wrote:
> The only other possibility I can think of is to use cdrdao
> to read the entire cd, then adjust the table-of-contents (toc) file so
> that the START of track 0 is 00:00:00, then burn the data using the
> edited toc file to a cd-r. In theory the resulting cd-r should then
> include the hidden track music as part of track 1 proper. I haven't
> actually tried this though.

[NB: That should have said "the START of track 1"]

I've now verified that this does in fact work. Removing the START
line in the toc file altogether would also have worked.

Of course the result is that, while the hidden music is now available,
it's part of track 1, not a track by itself. It's also possible to
edit the .toc file so that the hidden music is a separate track of its
own, but then cddb won't recognize the cd anymore.

I won't post the grimy details of doing all this, since it's a bit
complicated and there may well be a much simpler way of accomplishing
this job. But if you want the details, just ask and I'm happy to
oblige.

Couldn't one just drag the track from the CD image directly into the
Finder and then slice-and-dice in another program like Quicktime?

On 2004-04-17, Reginald Dwight wrote:
> Couldn't one just drag the track from the CD image directly into the
> Finder and then slice-and-dice in another program like Quicktime?

No. The track file as presented by the Finder doesn't include the
pre-gap.

In article ,
noman wrote:

> On 2004-04-17, Reginald Dwight wrote:
> > Couldn't one just drag the track from the CD image directly into the
> > Finder and then slice-and-dice in another program like Quicktime?
>
> No. The track file as presented by the Finder doesn't include the
> pre-gap.

Weird. Where is the icon of that file then? Is is invisible?

On 2004-04-18, Reginald Dwight wrote:
> In article ,
> noman wrote:
>
>> On 2004-04-17, Reginald Dwight wrote:
>> > Couldn't one just drag the track from the CD image directly into the
>> > Finder and then slice-and-dice in another program like Quicktime?
>>
>> No. The track file as presented by the Finder doesn't include the
>> pre-gap.
>
> Weird. Where is the icon of that file then? Is is invisible?

I don't know the low-level details of how audio cds work, but my
understanding is that they don't have file systems the way data cds
do, and therefore they don't have files either, in the usual sense.
They have tracks, which are indicated in the table-of-contents by a
start time and a duration. They can also have pre-gaps, but the
pre-gap is not part of the content of the track. When osx mounts an
audio cd, it pretends there's a file system there and treats the
content of each track as if it were a file. It never includes the
pre-gap data in these virtual files. As a result the pre-gaps are
completely inaccessible when an audio cd is treated as if it had
files.

Ordinarily this doesn't matter, since there's no audio data in the
pre-gaps anyway. But in these trick cds, audio material is 'hidden' in
the pre-gap of the first track. There's no way to get at this by
going through the osx file interface. You have to use some other
means.

Does that make more sense?

In article , noman
wrote:

> Does that make more sense?

Yes. Thank you. The only "hidden" tracks that I've dealt with thus far
weren't hidden at all - they were simply extensions of the CD's last
track. You know - last track is finished (or so we think) and then after
a five minute pause, the "hidden track" starts playing. I'd love to see
this WMBG disc. Alas, not a fan.

On 2004-04-17 23:09:51 -0400, Reginald Dwight said:

> In article , noman wrote:
>
>> Does that make more sense?
>
> Yes. Thank you. The only "hidden" tracks that I've dealt with thus far
> weren't hidden at all - they were simply extensions of the CD's last
> track. You know - last track is finished (or so we think) and then
> after a five minute pause, the "hidden track" starts playing. I'd love
> to see this WMBG disc. Alas, not a fan.

Go ahead and buy it. I won't tell anybody

Looking into the app noman used, I'm beginning to think it would be
easier just to record the audio to my hard drive. It's not like I'll
really notice a difference in quality once I rip it to mp3.
--
nomis

http://www.oozingbrain.com

home to _Withered Spirits: The Works of Terry Lamsley_
and _The Big F Webpage_ (diehards unite!)

On 2004-04-18, nomis wrote:
> Looking into the app noman used, I'm beginning to think it would be
> easier just to record the audio to my hard drive.

The procedure is really pretty simple: use cdrdao to make an image of
the cd (sort of) along with a table-of-contents (toc) file; edit the
toc file with any text editor; use cdrdao to burn a new cd with the
original image data and the edited toc. That's it.

Of course you need to install cdrdao in the first place and you need
to be comfortable with the command line interface (cli) to use it.
The latter can be kind of a big step if you don't have a unix
background, but it's absolutely worth doing: not using the cli in osx
is like buying a three-story house and never venturing above the
ground floor. Once you finally do it, you'll wonder what you could
have been thinking in avoiding it for so long.






> It's not like I'll
> really notice a difference in quality once I rip it to mp3.

That's certainly true. Otoh, if you burn a cd-r in which the hidden
track is more accessible, you can listen to easily in full fidelity
any time you want, on your mac or anywhere else.