7

Video formats can be characterized by the following factors:
• The medium used to store the video information: This is primarily videotape, but can
also be optical disc, solid-state memory, or a hard disk. For more information, see
“Storage Medium.”
• The size of the media and the shape of the shell: For example, videotape may be 1", 1/2",
3/4", or 8 mm. Many video formats have different shell sizes for portable and studio
use, such as mini-DV (portable) and the larger DV cassettes for studio decks. For more
information, see “Tape Size, Cassette Shape, and Tape Coating.”
• The video standard supported: For example, NTSC, PAL, ATSC (HDTV 1080i or 720p),
and so on. For more information, see “Video Standards.”
• The type of electronic signal recorded on tape: In other words, the way luma
(black-and-white) and chroma (color) information are combined and recorded. For
more information, see “Types of Video Signals.”
• The aspect ratio of the video frame: The ratio of the frame width to the frame height.
For more information, see “Aspect Ratio of the Video Frame.”
• The dimensions of the video frame: The number of pixels per line, and the number of
lines per frame. For more information, see “Frame Dimensions, Number of Lines, and
Resolution.”
• The aspect ratio of the pixels: This is a subtle factor that is explained in more detail in
“Pixel Aspect Ratio.”
• The frame rate: The number of frames recorded per second. For more information, see
“Frame Rate.”
• The scanning method: Interlaced fields (two fields per frame) or progressive (one
complete frame at a time). For more information, see “Scanning Method.”
• Color recording method: RGB, component (YUV), S-Video (Y/C), or composite. For more
information, see “Color Recording Method.”
• 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). For more
information, see “Color Recording Method.”
• Sample rate: The number of samples per second of each video line. This is just like the
sample rate for audio, except the signals sampled are video lines, where each sample
represents light intensity instead of sound intensity. For more information, see “Video
Sample Rate and Bit Depth.”
• 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. For more information, see “Bit
Depth.”
1892 Appendix B Video Formats