DVD Media

DVD is an optical disc storage media format that can be used to store data, including movies with high video and sound quality. DVDs seem compact discs: their physical dimensions are the same-12cm or the mini 8cm-but they are encoded in a different format and at a much higher density. Unlike CDs, all DVDs contain a filesystem. This file system is called UDF, and is an extension of the ISO 9660 Standard used for Data CDs. DVDs are made of a 0.6 mm thick disc of polycarbonate plastic coated with a much thinner (reflective) aluminum layer. Two such discs are glued together to form a 1.2 mm double-sided disc. The basic DVD disc is thinner than a CD to allow a lens to use with a higher numerical aperture make. A single-layer DVD 4.7 Gbyte, which is around seven times more than a standard CD-ROM can store. Using read laser at 650 nm (was 780 nm) wavelength and a numerical aperture of 0.6 (was 0.45), the read-out resolution is increased by a factor of 1.65. This applies to two dimensions, so the actual physical data density increases by a factor of 3.5. DVD uses a more efficient coding method in the physical layer. CD's error correction, CIRC, is replaced by a strong Reed-Solomon product code, RS-PC; Eight-to-Fourteen Modulation (EFM) is replaced by a more efficient version, EFMPlus, the same characteristics as the conventional EFM has. The CD subcode is removed. Due to the DVD format is 47% percent more efficient on the CD-ROM, a "third" error correction layer. DVD Media can contain: use DVD-ROM (read only, manufactured by a press) DVD-R / RW (R = Recordable once, RW = ReWritable) DVD-RAM (random access rewritable, after-write checking of data integrity is always active.) DVD + R / RW (R = Recordable once, RW = ReWritable) Two DVDs with different bottom sides.The disc one or two sides, and one or two layers of data per side, the number of sides and layers determines the disk capacity. DVD-5: single sided, single layer, 4,704,317,440 bytes, 4.7 gigabytes (GB), or 4.38 gibibytes (GiB) DVD-9: single sided, double layer, 8.5 GB (7.92 GiB) DVD-10 : double sided, single layer on both sides, 9.4 GB (8.75 GiB) DVD-14: double sided, double layer on one side, single layer on the other, 13.3 GB (12.3 GiB) DVD 18: double sided, double layer on both sides, is 17.1 GB (15.9 GiB) The capacity of a DVD-ROM are determined visually by noting the number of data sides, and look at the data side (n) of the disk. Double-layered sides are usually gold, while only a low sides are silvery, like a CD. An additional way to see if a DVD containing one or two layers is to look into the center ring at the bottom of the disc. If there are two barcodes, it is a dual layer disc. If a barcode is only one layer. Each medium is one of the above content and can contain any type layer. Double layer DVD + R discs are already on the market. Provider Info: Cdrdvdrmedia.com Tel: 1-626-854-2145 Toll Free: 1-888-813-5667 Fax: 1-626-854-6553 Website: http:/ / www.cdrdvdrmedia.com Profile about DVD Media ( http://www.cdrdvdrmedia.com) Cn Rambler Cdrdvdrmedia.com