Optical discs

Optical disc Optical disc drive Optical disc authoring Authoring software Recording technologies Recording modes Packet writing
Optical media types
Blu-ray Disc (BD): BD-R, BD-RE DVD: DVD-R, DVD+R, DVD-R DL, DVD+R DL, DVD-RW, DVD+RW, DVD-RW DL, DVD+RW DL, DVD-RW2, DVD-RAM, DVD-D, HVD Compact Disc (CD): Red Book, CD-ROM, CD-R, CD-RW, 5.1 Music Disc, SACD, PhotoCD, CD Video (CDV), Video CD (VCD), SVCD, CD+G, CD-Text, CD-ROM XA, CD-i Universal Media Disc (UMD) Enhanced Versatile Disc (EVD) Forward Versatile Disc (FVD) Holographic Versatile Disc (HVD) China Blue High-definition Disc (CBHD) HD DVD: HD DVD-R, HD DVD-RW, HD DVD-RAM High-Definition Versatile Disc (HDVD) High definition Versatile Multilayer Disc (HD VMD) VCDHD GD-ROM MiniDisc (MD) (Hi-MD) Laserdisc (LD) Video Single Disc (VSD) Ultra Density Optical (UDO) Stacked Volumetric Optical Disk (SVOD) Five dimensional discs (5D DVD) Nintendo optical disc (NOD)
Standards
Rainbow Books File systems ISO 9660 Joliet Rock Ridge / SUSP El Torito Apple ISO 9660 Extensions Universal Disk Format (UDF) Mount Rainier
Further reading
History of optical storage media High definition optical disc format war
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DVD-RW DL is a rewritable optical disc standard with storage capacity of 8.5 GB. DVD-RW DL discs employ two rewritable dye layers. It's approved by DVD Forum as "DVD Specifications for Re-recordable Disc for Dual Layer (DVD-RW for DL) Physical Specifications, Version 2.0".

Contents 1 Dual layer recording 2 See also 3 References 4 External links

[edit] Dual layer recording

Dual Layer recording allows DVD-R and DVD+R discs to store significantly more data, up to 8.5 gigabytes per side, per disc, compared with 4.7 gigabytes for single-layer discs. DVD-R DL was developed for the DVD Forum by Pioneer Corporation, DVD+R DL was developed for the DVD+RW Alliance by Philips and Mitsubishi Kagaku Media (MKM).^[1]

A Dual Layer disc differs from its usual DVD counterpart by employing a second physical layer within the disc itself. The drive with Dual Layer capability accesses the second layer by shining the laser through the first semi-transparent layer. The layer change can exhibit a noticeable pause in some DVD players, up to several seconds.^[2] This caused more than a few viewers to worry that their dual layer discs were damaged or defective, with the end result that studios began listing a standard message explaining the dual layer pausing effect on all dual layer disc packaging.

DVD recordable discs supporting this technology are backward compatible with some existing DVD players and DVD-ROM drives.^[1] Many current DVD recorders support dual-layer technology, and the price is now comparable to that of single-layer drives, though the blank media remains more expensive. The recording speeds reached by dual-layer media are still well below those of single-layer media.

There are two modes for dual layer orientation. With parallel track path (PTP), used on DVD-ROM, both layers start at the inside diameter (ID) and end at the outside diameter (OD) with the lead-out. With Opposite Track Path (OTP), used on DVD-Video, the lower layer starts at the ID and the upper layer starts at the OD, where the other layer ends, they share one lead-in and one lead-out.^[3]

[edit] See also

• DVD+RW DL

[edit] References

[edit] External links

• [1]

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