Apple Final Cut Pro 7 - Manual (Page 1893)

• Compressor (or codec): A video compressor attempts to reduce the amount of digital
data required to store each frame without compromising the quality of the image. For
more information, see
“Video Compression.”
Storage Medium
Video—especially digital video—can be stored on more than just videotape. The
characteristics of the storage medium determine playback and recording capabilities. For
example, magnetic and optical disc media (such as CDs, DVDs, and hard disks) are capable
of nonlinear reading and writing, whereas videotape is inherently linear. Videotape is still
a very efficient means of storing large amounts of digital data in a small space, but other
types of media are quickly gaining ground.
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, and 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.
About File-Based Media
Historically, video footage has been recorded on videotape. As digital acquisition replaces
analog technology, some camcorders now record footage as files on non-tape-based
media such as hard disks, solid-state cards, and optical discs.
Today, some common file-based media formats include:
• DVCPRO HD and AVC-Intra (solid-state Panasonic P2 card)
• AVCHD (hard disk, miniDVD, Secure Digital card, and memory stick)
1893 Appendix B Video Formats