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S-VHS

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S-VHS (Video Home System) is a consumer-level video standard developed by JVC and launched in 1976. Originally VHS was an acronym for Vertical Helical Scan (a reference to the recording system used) but was later changed to the more consumer-friendly Video Home System.


Contents

S-VHS format history

S-VHS (Super VHS) format was introduced by JVC in 1987 to fill a gap in the market between casual home users and video professionals. S-VHS uses both higher resolution (400 lines) and higher bandwidth than VHS, resulting in a significantly better picture quality. S-VHS also uses s-video connections, separating chrominance and luminance signals.

S-VHS format was an upgrade to the existing VHS format. S-VHS was designed to record at a higher horizontal resolution than VHS. The boost to detail came in the luminance domain (a.k.a. the black and white information), while the color resolution was still unchanged from VHS. The horizontal resolution specification for S-VHS was greater than 400 lines, compared to VHS, which was only 240 lines. Strangely, the increased detail in the black and white information sulted in an image that looked like the color saturation was low all the time.

S-VHS format description

Top view of S-VHS cassette with U.S. 25c coin for scale
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Top view of S-VHS cassette with U.S. 25c coin for scale
Bottom view of S-VHS cassette with magnetic tape exposed
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Bottom view of S-VHS cassette with magnetic tape exposed
Top view of S-VHS cassette with front casing removed
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Top view of S-VHS cassette with front casing removed

A S-VHS cassette contains a ½ inch (12.7 mm) wide magnetic tape wound between two spools, allowing it to be slowly passed over the various playback and recording heads of the video cassette recorder.

The catch with the S-VHS format was that the improved format required a special tape for the higher-resolution recording, and thus the S-VHS tape was born. Regular VHS tapes could not be used to record in the S-VHS mode because the cassette shell design prevented it. However, the S-VHS tapes are simply a higher grade of VHS tape, and nothing more.

In practice, most consumer S-VHS VCRs typically recorded only 360 to 380 lines at the best SP (standard play) speed, so they were not quite as good as the specification for the new format; still, this was a large leap in image quality. Some of the cheaper S-VHS VCRs of the time were actually down in the 340-line range for recorded horizontal resolution. The current JVC higher-end S-VHS units (circa 2001) record greater than 420 lines while their budget units are still in the 350-line range.

S-VHS format variations

Several improved versions of VHS exist, most notably S-VHS, an improved analogue standard, and D-VHS, which records high definition digital video onto a VHS form factor tape. Devices have also been invented which directly connect a personal computer to VHS tape recorders for use as a data backup device. W-VHS caters for analog high definition video.

Another variant is VHS-C (C for compact), used in some camcorders. Since VHS-C tapes are based on the same magnetic tape as full size tapes, they can be played back in standard VHS players using a mechanical adapter, without the need of any kind of signal conversion. The magnetic tape on VHS-C cassettes is wound on one main spool and uses a gear wheel to advance the tape; the wheel and spool can also be moved by hand. This development hampered the sales of the Betamax system somewhat, because the Betamax cassette geometry prevented a similar development.

There is also a JVC-designed component digital professional production format known as Digital-S or (officially) D9 that uses a VHS form factor tape and essentially the same mechanical tape handling techniques as an S-VHS recorder. This format is the least expensive format to support a pre-read edit. This format is most notably used by Fox for some of its cable networks.


S-VHS technical specifications

Signal standards

S-VHS only exists in PAL/625/25 and NTSC/525/30. S-VHS machines sold in SECAM markets record internally in PAL, and convert to/from SECAM during record/playback, respectively.

Tape lengths

Both NTSC and PAL/SECAM S-VHS cassettes are physically identical (although the signals recorded on the tape are incompatible.) However, as tape speeds differ between NTSC and PAL/SECAM, the playing time for any given cassette will vary accordingly between the systems.

Connections

To get the most benefit from S-VHS, a direct video connection to the monitor is required, ideally via an S-Video or component video connection. However, consumer S-VHS equipment was usually limited to S-Video and composite input jacks, with older television sets tending to also lack S-Video inputs. Nevertheless, viewing an S-VHS recording through a VCR's built-in RF modulator yields a discernable perceived quality improvement over VHS. Since the late 1990s, the increased popularity of S-VHS and other formats, such as DVD, has made S-Video and component video hookups commonplace on many TV sets.

It is not unusual to see the term S-VHS incorrectly used to refer to S-Video connectors, even in printed material. This may be due to S-VHS being one of the first consumer video products equipped with the S-Video connector; however, S-Video connectors are now common on American and Japanese video gadgets: DVD players and recorders, MiniDV camcorders, cable/satellite set-top boxes, etc.


S-VHS format future

S-VHS, a full-size format with resolution similar to that of HI-8, is virtually out of the consumer camcorder market. The format still is a strong player in the industrial market, but its future may be bleak with the release of newer and better digital formats. This format is used for videographers mostly for shooting and editing. The S stands for super, as the resolution jumps from the VHS standard of 250 lines to around 400 lines.

Unfortunately, most VCR's will not play a S-VHS tape and has to be transferred to a regular VHS format in order for it to be viewed on non-S-VHS machines.


See also

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