Apple Final Cut Express HD - Manual (Page 1026)

1026 Part XIII Appendixes
 The scanning method: interlaced fields (2 fields per frame) or progressive (one
complete frame at a time).
 Color recording method: RGB, component (YUV), S-Video (Y/C), or composite.
 Color sampling: For component digital formats, the ratio of color samples to black-
and-white (or luma) samples (for example, 4:4:4, 4:2:2, and 4:1:1).
 Sampling rate: the number of samples per second of each video line. This is just like
the sampling rate for audio, except the signals sampled are video lines, where each
sample represents light intensity instead of sound intensity.
 Bit depth: the number of bits used to store each video sample, which determines the
ability of the format to capture each sample’s (or pixel’s) light intensity precisely, and
how well subtle differences in intensity can be stored.
 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.
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 (CD, DVD, hard disk) are capable of
nonlinear reading and writing, while 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 video tape 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, BetacamSP and VHS both
use 1/2”-wide tape, but BetacamSP uses a high-quality component video recording
method that keeps luma and chroma information separate, while VHS uses a composite
method that mixes these signals into one, causing interference between the two. The
physical formulation of these two kinds of tape are also different, which accounts for
some of the quality difference.