DVD – A specification for storing digital data (usually
Encryption – Part of the DVD specification that requires that the digital data on the DVD disc be encoded in such a way that it cannot be read or decoded except by authorized playback devices. This was necessary to protect the content from illegal copying.
Field – One complete vertical scan of an interlaced video frame, representing half of the data in the frame. A field consists of all of the scan lines (each made up of pixels) that are on odd rows of the screen (“odd field”) or all of the scan lines that are on even rows of the screen (“even field”). Each field, therefore, contains half of the information in an interlaced video frame. Conventional video technology that uses interlacing (such as televisions) first displays all of the odd fields by displaying the top line (line 1), skipping a line (line 2), displaying the next line (line 3), and so forth until all of the odd lines that make up the field have been scanned. Then, the skipped (even) lines are displayed (between the odd lines, where they belong), and this process of alternating odd and even fields is repeated. Persistence (i.e., the ability of phosphor dots on the screen to remain lit for a period of time) gives the appearance of a complete image. Computer monitors are generally not operated in this manner; rather, they are updated with all scan lines in sequence (line 1, line 2, line 3, etc.), because they have shorter persistence phosphor and appear to flicker unless every line is rescanned every frame.
Frame – A single complete video image consisting of two interlaced fields (one odd and one even).
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