Computer Tool Software/soft.iso/Cdr/DAO.21C/QUICKCUE.TXT

Text File | 1996-04-14 | 3.6 KB | 81 lines

                        A QUICK AND DIRTY WAY
                   TO MAKE COPIES OF ANY AUDIO DISC


1) Use CDCLIP.EXE to copy the entire audio disc into a file on your
harddrive (Warning: this file could consume as much as 750Mb of disk
space).

2) Use QUICKCUE.EXE to generate a CUE SHEET file. This file will
contain the information needed to build the table-of-contents on
the new disc. NOTE: You must edit this file and add a FILE command
to specify the name of the file that was created by CDCLIP. Refer
to DAO.TXT to learn about cue sheets and the FILE command.

3) Use DAO.EXE to record your new disc using the files that were
created in steps 1 and 2.

The resulting CD will be exactly the same as the original except that
any "pause areas" between tracks will not be explicitly encoded on the
new disc (they will appear to be part of the tracks and not as a gaps
between tracks). The only noticable difference will be in the time values
displayed on your CD player. The actual amount of data on the disc and
the contents of the data will be identical.

**********************************************************************

Short lesson on tracks, indexes, and "pause areas"...

The table-of-contents (TOC) on a CDROM only specifies where each
track starts. It doesn't specify where each track ends. You may be
thinking "A track obviously ends one block before the start of the
next one". While this statement is true for some discs, it is usually
not the case. Each track can have an optional "pause area" between
itself and the previous track. Have you ever noticed that when you
play some CDs, one song will end, and then the display on your CD
player will count down -00:02 -00:01 -00:00, and then start the next
song? This is the pause area between two tracks. It is usually two
seconds long, but it can be more or less. The pause area usually
contains "digital silence", but this isn't required.

The starting time of any CD track is specified in minutes/seconds/frames.
There are 75 frames per second and each frame contains 2352 bytes of
audio data (75 * 2352 = 176400 bytes/second).

A disc is divided up into tracks, and the tracks are divided up into
smaller units called "indexes". There can be a maximum of 99 tracks
per disc and 99 indexes per track. The table of contents contains
pointers only to index 1 of each track. The other indexes must be
scanned for by the CD player. NOTE: Most CD players don't support
subindexes, which isn't a big deal since 99.99% of all CDs don't have
them anyway.

For each frame of data there is an additional 16 bytes of data (called
Subcode-Q data) that describes what track/index the frame belongs to
and the absolute/relative time of the frame. NOTE: Not all CDROM drives
on the market are capable of reading Q data and returning it to a user's
program. This is one of the reasons why it is difficult to produce an
exact bit for bit copy of an audio disc.

Let's say that an audio CD has the following table-of-contents...

TRACK 1 - 00:02:00
TRACK 2 - 04:50:00
TRACK 3 - 07:30:15
TRACK 4 - 10:15:60

Track 1 always begins at 00:02:00 (or higher). The "pause area" of the
first track is required and must be at least two seconds long.

The pause area is encoded with an index equal to zero, while the main
data area is encoded with an index equal to one.

TRACK 1 INDEX 0  00:00:00  ! two second pause
TRACK 1 INDEX 1  00:02:00  ! start of track 1
TRACK 2 INDEX 0  04:48:00  ! two second pause
TRACK 2 INDEX 1  04:50:00  ! start of track 2
TRACK 3 INDEX 0  07:29:15  ! one second pause
TRACK 3 INDEX 1  07:30:15  ! start of track 3
TRACK 4 INDEX 1  10:15:60  ! start of track 4 (no pause)