Instruction manual

53
Tech Notes
Books are written about many of the topics below, large and complex books. Look for them if you want more
information than what we have presented here. What we want to do here is to provide a bit more in depth
information, deeper background, on some relevant topics, and give you a framework for further technical
investigations.
Video Standards, Formats, and Quality
Video standards refer to the broadcast and/or viewing systems; they are specific to certain regions
of the world. In the US, Canada, and Japan, the analog standard is NTSC (which stands for National
Television Standards Committee, the organization that formalized the standard). In Europe (except France
and Eastern Europe), the standard is PAL (“phase alternate line”). In France, the Middle East, and most of
Eastern Europe, SECAM (“sequential coleur avec mémoire”) is the standard.
Why is this important? In part, because each standard requires compatible monitors, cameras,
VCRs, projectors, and switchers. The signals are electronically different from format to format, and so cannot
interoperate unless the equipment is specifically designed to be multi-standard.
Within each standard are multiple formats - different systems of recording video onto different types
of medium.
At the lowest quality and cost level is VHS, a composite form of video, meaning the chroma (color)
and luma (lightness) bits of information are electronically mashed together into one signal: convenient,
inexpensive, and very much of a compromise of image quality. Colors are not reproduced especially
brilliantly, but firsts generation quality is usually high enough for accurate viewing. 8mm is the similar format
but recorded on narrower tape. Plugs for composite video can be either RCA or BNC.
Y/C, or S-video, is so named because the chroma (C) and luma (Y) information is kept separate in
the signal, processed separately, and even transmitted separately. The result of this separation is far greater
color fidelity and detail. S-video can be recorded onto specially formulated VHS (S-VHS) or 8mm (Hi8) tapes.
There is a special 4 pin connector for Y/C signals.
There are many variations of 3 wire analog component video: Betacam, MII, etc. They are all
relatively (but not completely) similar ways of describing a color space like Y/C, except that the C component
is broken into 2 signals, for maximum color reproduction, fidelity, and detail. You may see the signal
described as RGB, YUV, YCC, Y B-Y R-Y. Usually cables with BNC connectors are used for component
signals.
DV, digital video, is a compressed 8 bit digital format that encodes video and audio into one digital
stream. The video is compressed at roughly 5:1; the audio can be either 2 16 bit channels sampled at 48 or
44.1 kHz or 4 12 bit channels sampled at 32 kHz. DV is transported, in digital form, via FireWire (or
IEEE1394 or iLink) cables, which can have 4 pin or 6 pin connectors. The signal is the same regardless of
the connector.
DVCAM and DVCPro are Sony’s and Panasonic’s (respectively) professional implementations of the
native DV spec. Encoding, sampling, audio, and compression are the same as DV, but the signals are stored
onto cassettes that have a more robust transport and better tape formulation.
SDI (Serial Digital Interface) is a standard for transmitting 10 bit component or composite digital
video and four channels of embedded digital audio along a single coax cable (with a BNC connector).