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Structure The file structure on a DVD is a Micro UDF, a universal disk format initially combined with ISO 9660. The Micro UDF file format extends what is currently possible with ISO 9660 The CCIR-601 is the digital video standard that specifies a video
rate of 167 megabits per second. At this bit rate, the 4.7 gigabyte capacity of a
standard DVD could only store roughly 4 minutes of digital video! Thus, some form of data
compression is required. As implemented for DVD, MPEG2 encoding is a two-stage process, where the signal is first evaluated for complexity. Then, higher bit rates are assigned to complex pictures and lower bit rates to simple pictures, using an "adaptive," variable bit-rate process. The DVD format uses 4:2:0 component digital video compressed to bit rates with a range of up to 10 megabits per second. Although the "average" bit rate for digital video is often quoted as 3.5 megabits per second, the actual figure will vary according to movie length, picture complexity and the number of audio channels required. CD VERSUS DVD PIT SIZE COMPARISON Compared to CD, DVD uses smaller pits and a more closely spaced track. The result is a significant increase in data density. The higher Numerical Aperture (NA) lens of DVD helps the laser focus on the smaller pits.
The DVD format provides multiple configurations of data layers. Each configuration providing additional data capacity. The configurations are:
The Single Side, Dual Layer
The Double Side, Dual Layer |