Re: [MacPerl] Querying audio CD for track pre-play times

[David Ackerman <dackerm@fas.harvard.edu>]

The information you are looking for on the compact disc is in the program
area of the Q subcode track.  The program area [mode 1] contains track
numbers, index numbers, track time, and absolute time.  The track running
time is set to 0 at the beginning of each track and increases till the end
of the track.  At the beginning of the pause, time decreases until 0 is
reached at the end of the pause. and so on till the disc lead out.

Further a pause can be identified by the index number (X).  When set to
00, X designates a pause between tracks.  A non-zero X indicates index
points within the track.  A vaule of 01 designates the lead out.

hope this helps some.

**********************************
David Ackerman
Audio Preservation Engineer
Archive World Music
Harvard University
Cambridge, MA 02138
**********************************

On Wed, 19 Apr 2000, Ken Williams wrote:

> ajf@afco.demon.co.uk (Alan Fry) wrote:
> >At 8:26 pm -0500 18/04/00, Ken Williams wrote:
> >What exactly do you mean by "pre-track pause"? To the best of my 
> >knowledge the only information on the disc about the contents of the 
> >disc is the absolute start time (in minutes, seconds and frames) of 
> >each track. This is returned by Mac.pm in 'cd_toc' ( and in 
> >alternative format by 'cddb_toc').
> 
> I'm not sure how it's implemented on the disc, but that information is
> definitely there.  You can observe it on most commercially-produced CDs
> by noting that before many tracks the timer will count down -00:02,
> -00:01, 00:00, 00:01, ....
> 
> In Toast, you can manually set the pause before each track.  This adds
> the countdown time before each track starts playing.
> 
> [does a little research...]
> 
> According to the Toast manual (v.4 p.4-22), the silences are simply
> empty sectors on the disk before each track, and run-out sectors after
> each track.  The standard pause of 2 seconds seems to be 150 empty
> sectors and 2 run-out sectors.  This is my first reading of the
> information, so I might still have a misunderstanding of it.
> 
> So perhaps what I'm looking for is a way to figure out how many empty sectors
> precede each track?
> 
> >The CPAN distribution of Mac.pm certainly does include the compiled 
> >binary for Mac.xs and it works fine. There has been quite a lot of 
> >discussion in these pages in recent times about installing modules on 
> >the Mac and to say the least I am not the best person to add anything 
> >to that.
> 
> After Chris told me that the distribution is supposed to include the
> binary fies, I tried dropping it on my Stuffit Expander and found that
> the files appeared.  Copying them manually to my site_perl folder fixed
> the installation.  But installme.plx didn't work, it didn't extract the
> binary files.
> 
> 
> 
> 
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