DVD-R DL

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Optical disc authoring

Optical disc Optical disc image Optical disc drive Authoring software Recording technologies Recording modes Packet writing
Optical media types
Laserdisc Compact disc (CD): Red Book, 5.1 Music Disc, SACD, PhotoCD, CD-R, CD-ROM, CD-RW, Video CD, SVCD, CD+G, CD-Text, CD-ROM XA, CD-Extra, CD-i Bridge, CD-i MiniDisc DVD: DVD-R, DVD+R, DVD-R DL, DVD+R DL, DVD-RW, DVD+RW, DVD-RW DL, DVD+RW DL, DVD-RAM, DVD-D HD DVD: HD DVD-R, HD DVD-RW, HD DVD-RAM Blu-ray Disc (BD): BD-R, BD-RE UDO UMD Holographic data storage 3D optical data storage History of optical storage media
Standards
Rainbow Books File systems ISO 9660 Joliet Rock Ridge Amiga Rock Ridge extensions El Torito Apple ISO9660 Extensions Universal Disk Format Mount Rainier

DVD-R DL (DL stands for Dual Layer), also called DVD-R9, is a derivative of the DVD-R format standard. DVD-R DL discs employ two recordable dye layers, each capable of storing nearly the 4.7 GB (4.38 GiB) of a single-layer disc, almost doubling the total disc capacity to 8.54 GB (7.96 GiB). Discs can be read in many DVD devices (older units are less compatible) and can only be written using DVD-R DL compatible recorders.

DVD-R DL	Capacity
Physical size	GB	GiB
12 cm, single sided	8.5	7.92
12 cm, double sided	17.1	15.93
8 cm, single sided	2.6	2.42
8 cm, double sided	5.2	4.84

DVD-R DL has compatibility issues with legacy DVD-ROM drives known as pickup head overrun. To avoid this issue, the two layers of the disc need to be equally recorded. But this is a contradiction with the sequential nature of the DVD recording. Thus DVD Forum under Pioneer's lead developed a technology known as Layer Jump Recording (LJR), which incrementally record smaller sections of each layer to maintain compatibility with DVD-ROM drives.

[edit] Recordable DVD capacity comparison

For comparison, the table below shows storage capacities of the four most common DVD recordable media, excluding DVD-RAM. (SL) stands for standard single-layer discs, while DL denotes the dual-layer variants. See articles on the formats in question for information on compatibility issues.

Disk Type	number of sectors for data (2,048B each)	capacity in bytes	capacity in GB	capacity in GiB
DVD-R (SL)	2,298,496	4,707,319,808	4.7	4.384
DVD+R (SL)	2,295,104	4,700,372,992	4.7	4.378
DVD-R DL	4,171,712	8,543,666,176	8.5	7.957
DVD+R DL	4,173,824	8,547,991,552	8.5	7.961