Notes on Optical Media Formats

DVD Forum
An international organization devoted to the research, development, and propagation of the DVD and DVD-R/RW formats. Originally founded in 1995 under the name DVD Consortium. Membership is available to any organization involved in DVD research or production, as well users interested in the format. When the HD DVD format was released, a split occurred with DVD Forum members regarding whether to support the HD DVD or Blu-Ray format.

DVD+RW Alliance
A group of hardware, software, and optical storage manurfactures who's mission is to develop and promote an optical media format that is cross-compatible between personal computer technology and standalone consumer-products (i.e. DVD players). Originally founded in 1997.
 * Blu-ray Disc Association
 * DVD-RAM Promotion Group (RAMRPG)

DISC FORM-FACTORS
CD/DVD/Blu-ray
 * 120mm diameter
 * 1.2mm thickness

DVD-ROM
Digital Video Disc-Read Only Memory was developed in 1995 by Phillips, Panasonic, Sony, and Toshiba. Manufactured DVD-ROMs have their data stamped on to the readable portion of the disc, and cannot be written nor erased. The data is written from the center of the disc spiraling out to the perimeter; similar to a vinyl record. DVD's are able to record more data than a CD due to the use of a smaller laser (650nm versus 780nm) among other features.

DVD-R [DVD Forum]
Uses a write-once organic dye that is scorched by the optical drive's laser to imprint "pits" on the surface of the media in order to record the media. Introduced by Pioneer in 1997. 4.7 GB storage

DVD-RW [DVD Forum]
Re-writable DVD-s were deveolped by Pioneer in 1999. According to Pioneer, a DVD-RW can be written to up to 1000 times (Ha!). A key benefit to DVD-RWs is that if a write operation is corrupted, the disc isn't ruined and can be written over. Rather than the organic dyes used in DVD-Rs, DVD-RWs utilize a metal-alloy that is able to switch between crystalline (written) and amorphous (writable) states. 4.7 GB storage

DVD+R/RW [DVD+RW Alliance]
Originally developed in 1997, DVD+R/RW media wasn't released to the market until 2002. DVD+R/RW media incorporated newer technologies than in DVD-R/RW in its writing operations that allowed DVD+R/RW better data integrity at faster write speeds. However, DVD-R/RW media has been available since 1997 which has enabled DVD-R/RW media to carve out a significant portion of the market that persists today. Current market trends show that DVD-R/RW and DVD+R/RW formats are equally viable today. This is largely due to most modern optical drives (since about 2006) supporting either format. 4.7 GB Storage

DVD+-R DL [DVD Forum][DVD+RW Alliance]
Dual Layer DVD+-R format, almost doubling the capacity of standard DVD-Rs, albeit at a slower write speed. Introduced by Pioneer in 2005. There are literally two layers of writable surface, which involves the laser of a standard DVD player shining through the first semi-transparent layer of the media, causing a significant delay in read times. 8.5 GB storage

DVD+-RW DL [DVD Forum][DVD+RW Alliance]
Dual layer specifications for DVD+-RW were put forward by the DVD Forum. However, the release and propagation of HD DVD and Blu-ray formats, with their greater storage capacities, preemptively made the specification obsolete. 8.5 GB storage

DVD-RAM [DVD Forum]
Originally developed in 1996. Per manufacturers, DVD-RAM can be rewritten to over 100,000 times with an estimated 30 years of data retention (versus 2-10 years of retention for DVD+-RW formats with a maximum of 1000 writes). Rather than writing data in a single, spiraling string as in DVD and DVD+-R/RW formats, DVD-RAM stores data in concentric tracks on the media surface, similar to floppy and hard disk drives. This has the added benefit of increasing the speed in which data is written and erased. Unfortunately, the DVD-RAM format is prohibitively expensive relative to DVD+-RW formats, and ill-supported among manufacturers. These factors contribute towards its rarity amongst optical medias available today.

Blu-ray
The next generation of optical media, Blu-ray disks can hold up to 128GB of data (with quadruple layers). The greater capacity of Blu-ray disk versus DVD media is due to the blue (and therefore shorter wavelength) laser of Blu-ray drives. Blu-ray lasers have a wavelength of about 400nm; compared to the 650nm of DVDs and 780nm of CDs. The Blu-ray is the clear winner of the '06-'08 format war against the HD DVD (whose development was ceased in 2008).

TERMS

 * Optimum Power Calibration (OPC)
 * Measure of laser parameters to determine compatible writable medias