The CD-R technology
CD Recorder drives currently are available in a variety of different recording speeds. Single speed (1X) CD-R drives record in real time
(same as the playback speed of the CD). Faster drives record at multiples of the playback speed, and as a result, reduce writing time. A
six-speed (6X) drive, for example, can write a 74-minute CD in 12 minutes.
The primary concern when writing at speeds higher than 2X is ensuring that your computer can provide a fast, consistent data flow
during the burning process. The biggest danger with writing CDs at high speeds is running out of data while the CD-R drive and
software are working. If the computer cannot keep up with the CD-R drive being utilized, a buffer underrun will occur and your blank
CD-R disc will be ruined.
Because the Orange Book specification only partially defines CD-R drives, many subtle differences among recorders have resulted.
Different CD-Recorders use lasers of different intensities, which results in differences in the optimal marks created in the “burning”
process. Buffers, writing modes, and interface type have also been left up to the discretion of the individual manufacturers.
Although consideration should be given to these subtle differences, keep in mind that all drive manufacturers must stay within certain
defined ranges. Consequently, although lasers may be of varied intensities, they must all stay within the prescribed range of 4 to 8
milliwatts. Therefore, it is unlikely that writing quality will be significantly affected.
Writing speed, on the other hand, must be taken into consideration when choosing your CD-R disc. CD-R discs can come in one of four
states: a pregrooved and time-stamped blank disc, a closed multisession disc, a finalized disc, and a partially recorded disc. CD-R discs
are also formulated for optimum performance with CD-R drives recording at high writing speeds. The reason for this is simple. A laser of
a certain intensity will create an optical mark depending on the speed in which the disc is spinning. Therefore, recording at a greater
speed will affect the characteristics of the optical mark created. Due to this alteration, disc manufacturers have reformulated their discs
to operate in accordance with the higher recording speed of the latest CD-R drives.
It is very important to find out what CD-R disc your drive manufacturer recommends. Some drives will check the make of the disc prior
to playing and not let you write if it does not meet the drive specification.
Audio is recorded to the CD-R disc primarily in one of two fashions: track-at-once (TAO) or disc-at-once (DAO).
Track-at-Once
Track-at-once (TAO) writing records either one track or multiple tracks to the disc and results in a partially recorded disc. Because the
data in the program area is written before the lead-in area (including the table of contents), the CD-R disc remains unplayable on most
systems until you add the final track and perform a final fixation. The advantage of TAO writing is that you can record tracks onto the
disc as you finish them versus waiting until you have finished your whole album. The downfalls of TAO writing lie in the loss of storage
space and in the creation of run-out sectors, which are created as the laser shuts off after each writing session. Run-out sectors not only
result in a loss of 13.5MB of disc space each time a session is written to the disc, but they also manifest themselves as “clicks” in the
music. CD Architect
™
does not use this method.
Disc-at-Once (Single Session)
Disc-at-once (DAO) writing, the method used in CD Architect, is the most common burning method in the music industry. This writing
mode is used when creating a master disc to be sent to a disc manufacturer for mass replication. Disc-at-once works just as it sounds.
Once the premastering software has created a cue sheet, the table of contents (TOC) is written to the lead-in area. At this point, the
audio to be recorded is written to the CD in one recording session. After all of the audio has been written, a final fixation is automatically
performed by writing the required silence to the lead-out area. This writing procedure is opposite of track-at-once writing, in which the
TOC is written to the lead-in area after all data has been written to the disc.
Other than a computer capable of providing a fast data stream, the last item you will need to burn your own CDs is, of course, the item
you just purchased: CD recording software. Undoubtedly, the most important part of the equation, CD recording software is the
determining factor for operational ease, functionality, and overall performance.
Congratulations on choosing the best: CD Architect.
OVERVIEW OF CD TECHNOLOGY | 11