Editing CD-R (section)

==Writing methods==

The blank disc has a pre-groove track onto which the data are written. The pre-groove track, which also contains timing information, ensures that the recorder follows the same spiral path as a conventional CD. A [[CD recorder]] writes data to a CD-R disc by pulsing its laser to heat areas of the organic dye layer. The writing process does not produce indentations (pits); instead, the heat permanently changes the optical properties of the dye, changing the reflectivity of those areas. Using a low power laser, so as not to further alter the dye, the disc is read back in the same way as a CD-ROM. However, the reflected light is modulated not by pits, but by the alternating regions of heated and unaltered dye.<ref>{{cite magazine|date=March 1996|title=The Next Generation 1996 Lexicon A to Z: CD-Recordable|url=https://archive.org/details/nextgen-issue-015/page/n31/mode/2up|magazine=[[Next Generation (magazine)|Next Generation]]|publisher=[[Imagine Media]]|issue=15|page=31|quote=In actual CDs, pits carved into the surface of the CD are read by the laser in the CD-ROM drive. CD-Recordables, or CD-Rs, simulate the pits by putting ink spots on the CD.}}</ref> The change of the intensity of the reflected laser radiation is transformed into an electrical signal, from which the digital information is recovered ("decoded"). Once a section of a CD-R is written, it cannot be erased or rewritten, unlike a [[CD-RW]]. A CD-R can be recorded in multiple sessions.
A [[CD recorder]] can write to a CD-R using several methods including:
# [[Disc At Once]] – the whole CD-R is written in one session with no gaps and the disc is "closed" meaning no more data can be added and the CD-R effectively becomes a standard read-only CD. With no gaps between the tracks, the Disc At Once format is useful for "live" audio recordings.
# [[Track At Once]] – data are written to the CD-R one track at a time but the CD is left "open" for further recording at a later stage. It also allows data and audio to reside on the same CD-R.<ref>{{Cite web|url=http://digitalexpressmastering.com/mastering/|title=Audio Mastering Is Now Possible|website=digitalexpressmastering.com|language=en-US|archive-url=https://web.archive.org/web/20140522224807/http://digitalexpressmastering.com/mastering/|archive-date=2014-05-22|url-status=dead|access-date=2017-02-21}}</ref>
# [[Packet Writing]] – used to record data to a CD-R in "packets", allowing extra information to be appended to a disc at a later time, or for information on the disc to be made "invisible". In this way, CD-R can emulate CD-RW; however, each time information on the disc is altered, more data has to be written to the disc. There can be compatibility issues with this format and some CD drives.

With careful examination, the written and unwritten areas can be distinguished by the naked eye. CD-Rs are written from the center outwards, so the written area appears as an inner band with slightly different shading.

CDs have a Power Calibration Area, used to calibrate the writing laser before and during recording. CDs contain two such areas: one close to the inner edge of the disc, for low-speed calibration, and another on the outer edge on the disc, for high-speed calibration. The calibration results are recorded on a Recording Management Area (RMA) that can hold up to 99 calibrations. The disc cannot be written after the RMA is full, however, the RMA may be emptied in CD-RW discs.<ref>{{Cite web|title=Everything you Wanted to Know About CDs|url=http://www.co-bw.com/Audio_everything_you_wanted_to_know_about_CDs.htm|url-status=dead|archive-url=https://web.archive.org/web/20170221220033/http://www.co-bw.com/Audio_everything_you_wanted_to_know_about_CDs.htm|archive-date=February 21, 2017|website=www.co-bw.com}}</ref>

===Formatting CD-R into CD-ROM===
Choosing a ''finalize disc'' or ''close disc'' option during a burn setup, it will no longer accept any future writes, and become read-only.