DVD-RAM
DVD-RAM (DVD Random Access Memory) is a DVD-based disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders ...
, have their data encoded on a single spiral, or a ''groove'', which covers the surface of the disc. In the case of recordable media, this spiral contains a slight
sinusoidal
A sine wave, sinusoidal wave, or just sinusoid is a mathematical curve defined in terms of the '' sine'' trigonometric function, of which it is the graph. It is a type of continuous wave and also a smooth periodic function. It occurs often i ...
deviation from a perfect
spiral
In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point.
Helices
Two major definitions of "spiral" in the American Heritage Dictionary are:constant linear velocity while writing a disc, but has other uses as well depending on the type of disc. The frequencies quoted all assume that the disc is being written at the '1x' speed. The frequencies are appropriately higher for faster writing speeds.
CD-R
CD-R (Compact disc-recordable) is a digital optical disc storage format. A CD-R disc is a compact disc that can be written once and read arbitrarily many times.
CD-R discs (CD-Rs) are readable by most CD readers manufactured prior to the i ...
DVD-R
DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('bu ...
and
DVD-RW
DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('bur ...
have a constant wobble frequency of 140.6 kHz relying on data 'pits' beside the groove to convey information (Land pre-pit).
DVD+R
DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('bu ...
and
DVD+RW
DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('burn ...
have a constant wobble frequency of 817.4 kHz, but encodes its addressing information by periodically inverting the phase of the wobble signal (bi-phase modulation) to encode an exact address of the location on the spiral track (Address in Pregroove). The practical upshot of this arrangement is that the recording drive can navigate to an exact location on the DVD+R(W) disc whereas it cannot do so with the DVD-R(W).
BD-R
Blu-ray Disc Recordable (BD-R) refers to two direct to disc optical disc recording technologies that can be recorded on to a Blu-ray-based optical disc with an optical disc recorder. BD-R discs can be written to once, whereas Blu-ray Disc Recorda ...
and BD-RE http://www.blu-raydisc.com/Assets/Downloadablefile/White_Paper_BD-RE_5th_20180216.pdf discs utilise Address in Pregroove.
HD DVD
HD DVD (short for High Definition Digital Versatile Disc) is an obsolete high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the ...
-R and HD DVD-RW use the land pre-pit system of the DVD-R(W).