Appendix
40
Track-at-Once (TAO)
This method is used to write data on a disc on a track-by-track basis. A track
can be defined as the smallest unit of area that contains an ordinary program,
pictorial data, text data, etc. This method allows you to add data to the same
disc, one track of data at a time, as long as there is free space left on the disc.
Discs that contain data recorded in several different sessions (writing of
tracks) are referred to as multi-session discs.
Multi-session discs cannot be played on any ordinary audio CD player, except when
data is recorded in a single session, or except for the first session.
Session-at-Once (SAO)
This method is used to write data on a disc on a session-by-session basis.
Unlike Track-at-Once described above, Session-at-Once allows you to
record multiple tracks onto a disc at one time. CD EXTRA, for example,
uses this method to record multiple pieces of audio data (or multiple tracks)
in the first session and information required for computers in the second
session. This method allows you to add data to the same disc, one session at
a time, as long as there is free space left on it. As is the case with discs
containing data recorded by Track-at-Once method, discs containing data
recorded by this method can also be called multi-session discs, provided that
data is written in several different sessions.
Note
0
Data
Track 1
1st session
Data
Track 2
2nd session
Data
Track 3
3rd session
Lead-in
Lead-out
/Lead-in
Lead-out
/Lead-in
Lead-out
Data can be added if there is
free space left on the disc.
0
Example: CD EXTRA
Audio data
Track 1
Audio data
Track 2
Audio data
Track 3
Audio data
Track 4
1st session
2nd session
Lead-in
Lead-out/
Lead-in
Lead-out
