Layout of recordable DVD
The DVD disc is divided into four areas or zones as shown in Figure 22.15. The main zone is the data or information zone where video and audio data are recorded. This is preceded by a burst cutting area which is between 44
and 47 mm from the centre of the disc. The information zone itself com- mences with lead-in zone and followed by a lead-out area.
Before the video and audio data are recorded in the user area, the data bits are grouped into 2048-byte chunks or sectors. Each sector commences with a header which includes, among other things, a unique ID number for the sector. The data is written on the disc surface, sector by sector. Reading the data off the disc involves directing the pickup head to the part of the disc surface where the required sector is recorded and once the sec- tor is identified, data is extracted for further processing.
