Tape Size, Cassette Shape, and Tape Coating
The width of a videotape is directly related to how much information can be stored. In
analog formats, wider tape usually yields higher quality, but other factors can help
reduce tape size with minimal loss of quality. For example, Betacam SP and VHS both
use 1/2"-wide tape, but Betacam SP uses a high-quality component video recording
method that keeps luma and chroma information separate, whereas VHS uses a
composite method that mixes these signals into one, causing interference between the
two. The physical formulations of these two kinds of tape are also different, which
accounts for some of the quality difference.
The size of the cassette itself can vary as well. For example, the Betacam SP format
comes in both small and large sizes. The small tapes are used for camcorders, while the
large format is used in studio VTRs.
Aspects of the physical composition of magnetic tape, such as density of magnetic
particles, limit the data rate and track size that can be recorded on the tape. The
magnetic coating on a videotape is formulated to work with particular camcorders and
VTRs. If you choose the wrong tape coating, the tape can actually clog the video record
heads of your video equipment, leading to video signal dropouts during recording and
playback. Always read the documentation that comes with your video equipment
before purchasing a particular brand of videotape stock.
Appendix A
Video Formats
377
V