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Writing a DVD at 1× (1 385 000 bytes per second) [5] is approximately 9 times faster than writing a CD at 1× (153 600 bytes per second). [6] However, the actual speeds depend on the type of data being written to the disc. [6] For Blu-ray discs, 1× speed is defined as 36 megabits per second (Mbit/s), which is equal to 4.5 megabytes per second ...
DVD Forum's DVD Books [1] [2] [3] and DVD+RW Alliance specifications: Developed by: Sony Panasonic Philips Toshiba: Dimensions: Diameter: 12 cm (4.7 in) Thickness: 1.2 mm (0.047 in) Weight: 16 grams (0.56 oz) Usage: Home video, Computer data storage: Extended from: LaserDisc Compact disc: Extended to: DVD+RW, DVD-RAM (Fixed-track writable media ...
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 ...
Each CD track has an index; however, it is rare to find a CD player that displays or can access this feature, except occasionally in pro audio equipment, usually for radio broadcasting. Every track at least has index 1, and often has a pre-gap which is index 0. Additional songs, such as "hidden tracks", may have index 2 or 3.
Low-density parity-check (LDPC) codes are a class of highly efficient linear block codes made from many single parity check (SPC) codes. They can provide performance very close to the channel capacity (the theoretical maximum) using an iterated soft-decision decoding approach, at linear time complexity in terms of their block length.
For a miniature disc with a diameter of 8 cm (radius of 4 cm), the speed ratio of outer to inner data edge is 1.6. This means that, for example, if a disc is accessed at a constant angular velocity of ×24, the equivalent linear velocity is ×24 while accessed at the outermost edge of the data area while being ×10 at the innermost data area.
For comparison with analogue media, the pitch of the spiral of a 240-groove-per-inch long-playing record and a Laserdisc are 106 μm (66 times the CD track pitch) and 4.6 μm (2.9 times), respectively. The tip of a 0.7-mil stylus has a diameter of 18 μm (11 times that of the CD laser spot). Data is from , , and .
It was resolved with both surviving however: DVD-R predominating for stand-alone DVD recorders and players, and (for computers) most DVD devices being engineered as dual format, to be compatible with both. As of 2007 DVD is the de facto standard for pre-recorded movies, and popular storage of data beyond the capacity of CD.