Adobe Premiere 5.0 Classroom in a Book


Flying erase head
Video recorders record on video tape in a pattern called helical scanning. The recording is made by a recording head attached to a rotating drum that is at an angle to the tape. The figure below shows the helical pattern the recording head writes to the tape.

Also on the tape may be separate audio and control tracks. This varies from format to format - for example, 8mm tape stores audio in the helical part of the track.

Inexpensive recording decks use a separate erase head that erases in a direction perpendicular to the tape rather than in the helical pattern. This can result in only part of the track being erased, which causes the synching problems and color banding at edit points common with inexpensive VHS decks. A flying erase head is mounted on the drum, and erases the helical tracks correctly and makes clean edits possible.

The helical scan pattern. Cheaper recording decks have an erase head which is perpendicular to the tape, as shown here. Better decks have an erase head which is parallel to the scan pattern

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