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A standard single-layer DVD can store up to 4.7 GB of data, a dual-layer DVD up to 8.5 GB. Variants can store up to a maximum of 17.08 GB. [11] Prerecorded DVDs are mass-produced using molding machines that physically stamp data onto the DVD. Such discs are a form of DVD-ROM because data can only be read and not written or erased.
Hard disk drives store data in the magnetic polarization of small patches of the surface coating on a disk. The maximum areal density is defined by the size of the magnetic particles in the surface, as well as the size of the "head" used to read and write the data. In 1956 the first hard drive, the IBM 350, had an areal density of 2,000 bit/in 2.
During the burning of a single bit, the laser's intensity affects the reflective properties of the burned dye. By varying the laser intensity quickly, high density data is written in precise tracks. Since written tracks are made of darkened dye, the data side of a recordable DVD has a distinct color.
Dual-layer recording allows DVD-R and DVD+R discs to store significantly more data, up to 8.5 gigabytes per disc, compared with 4.7 gigabytes for single-layer discs. DVD-R DL was developed for the DVD Forum by Pioneer Corporation, while DVD+R DL was developed for the DVD+RW Alliance by Philips and Mitsubishi Kagaku Media (MKM).
HD DVD (short for High Density Digital Versatile Disc) [1] is an obsolete high-density optical disc format for storing data and playback of high-definition video. [2 ...
The data is at the same depth (0.6 mm) as DVD as to minimize damage from scratching. As with DVD the construction of the HD DVD allows for a second side of either HD DVD or DVD. A study performed by Home Media Magazine (August 5, 2007) concluded that HD DVDs and Blu-ray discs are essentially equal in production cost.
DVD-R DL (DL stands for Dual Layer [1]), also called DVD-R9, is a derivative of the DVD-R format standard. DVD-R DL discs hold 8.5 GB by utilizing two recordable dye layers, each capable of storing a little less than the 4.7 gigabyte (GB) of a single layer disc, almost doubling the total disc capacity. [ 2 ]
If the data density is the same everywhere on the disc, as is the case with CD and DVD and Blu-ray discs, the linear velocity directly correlates with the transfer rate (read speed or write speed), meaning an increase in linear velocity also increases the amount of data read from the disc in the same time, regardless of whether the laser is ...