Digital video is a type of video recording system that works by using a digital, rather than analog, representation of the video signal. This generic term is not to be confused with the name DV, which is a specific type of digital video. Digital video is most often recorded on tape, then distributed on optical discs, usually DVDs. There are exceptions, such as camcorders that record directly to DVDs, Digital8 camcorders which encode digital video on conventional analog tapes, and the most recent JVC Everio G camcorders which record digital video on hard disks.
The terms “camera”, “video camera”, and “camcorder” are used interchangeably in this article.
Video cameras come in two different image capture formats: interlaced and progressive scan. Interlaced cameras record the image in alternating sets of lines: the odd-numbered lines are scanned, and then the even-numbered lines are scanned, then the odd-numbered lines are scanned again, and so on. One set of odd or even lines is referred to as a “field”, and a consecutive pairing of two fields of opposite parity is called a frame.
A progressive scanning digital video camera records each frame as distinct, with both fields being identical. Thus, interlaced video captures twice as many fields per second as progressive video does when both operate at the same number of frames per second. This is one of the reasons video has a “hyper-real” look, because it draws a different image 60 times per second, as opposed to film, which records 24 or 25 progressive frames per second.
Progressive scan camcorders such as the Panasonic DVX100 are generally more desirable because of the similarities they share with film. They both record frames progressively, which results in a crisper image. They can both shoot at 24 frames per second, which results in motion strobing (blurring of the subject when fast movement occurs). Thus so, progressive scanning video cameras tend to be more expensive than their interlaced counterparts. (Note that even though the digital video format only allows for 29.97 interlaced frames per second [or 25 for PAL], 24 frames per second progressive video is possible by displaying identical fields for each frame, and displaying 3 fields of an identical image for certain frames. For a more detailed explanation, see the adamwilt.com link.)
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