Appendix
29
Session-at-Once (SAO)
As a writing method that combines the advantages of the above-mentioned “Disc-at-
Once” and “Track-at-Once,” you can combine multiple tracks into one session and
write them, and then add additional data.
For example, this is the writing method used to create a CD EXTRA format CD. The
music tracks will be recorded in the first session, and the data will be recorded in the
second session.
Packet Writing
This mode is used when writing to a track of a disc using small blocks of data called
“packets,” in a manner similar to a floppy disk. This mode is useful when making
small incremental backups of data. You will need to use software that specifically
supports packet writing.
Notes on Packet Writing
• Discs must be formatted before they can be used for packet writing. With CD-RW, erased data
can be overwritten until the disc is completely full.
• When using packet writing on a CD-RW disc, the actual data capacity is 100MB less than that
stated on the cover of the disc. The difference in capacity is dependent on the writing mode.
• With CD-R, the space used by the erased data cannot be reused and is “masked” so that it is no
longer visible. This can be done up to 100 times.
Lead-in
Lead-out
Lead-out
/Lead-in
Data
Audio
Audio
Audio
Track 1
Track 2
Track 3
Track 4
Session 1
Session 2
Example: CD EXTRA
1
2
3
4
5
6
7
8
.
.
.
.
.
.
.
.
.
.
.
.
Packet
Same as writing to floppy or hard disk
