Friday, June 29, 2012

The Logic Structure and Data Structure of DVD Discs

Logic Structure

A DVD disc always contains a logical volume. For the multi-layer DVD disc, the volume is divided into layers corresponding to the partition. A logical volume inside the basic logic unit is a logical sector, which contains 2048 bytes, and corresponds to a physical sector.

Volume mainly consists a volume and file structure, DVD-Video zone and non-DVD-Video zone (the area is optional), the video files on DVD-Video zone, computer data on non-DVD-Video zone, so you can a DVD disc with video stored on the computer programs and computer games. 

Data Sructure

DVD disc is set with navigation data (that is playback data) and presentation data (Which includes audio, video, subgraph and so on) in all two data structures. Users can play the audio, video, subgraph by scanning the control information.

• The structure of navigation data
The navigation data is to control how to play data, which is made up by VMGI, VTSI, PGCI, PCI and DSI five parts.

• Presentation data
Presentation data is made up by audio, video and subgraph. It contains at least one program, and each program shall include a PGC. The first PGC of each program shall always be Entry PGC. In the program with only one PGC, the PGC is Entry PGC. 

A program chain PGC by the program chain information PGCI and video objects VOB set in the unit. PGCI is made up by the pre-command and post-command. These units point to VOBS unit, it defines the playback of the order for these units. 

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