name = Video Home System |
caption = Top view of VHS cassette with ruler for scale
encoding = FM on
common lengths = 120, 160 minutes (Standard Play Mode)
unusual lengths = 5, 10, 15, 30, 60, 90, 130, 180, 190, 200, 210 minutes (Standard Play Mode)
JVC(Japan Victor Company)
use = Audio/Video Storage
The Video Home System [ [http://www.ieee.org/web/aboutus/history_center/vhs.html "IEEE History Center: Development of VHS"] , cites the original name as "Video Home System", from an article by Yuma Shiraishi, one of its inventors. Accessed
December 28, 2006.] , better known by its abbreviation VHS, is a recording and playing standard developed by Victor Company of Japan, Limited (JVC) and launched in Europe/Asia in September 1976("U.S. launch was June 1977"), with " The Young Teacher" being the first movie to be released and "A History of Violence", released on home video in 2006, being the last in the North American market. [ [http://citypaper.com/film/story.asp?id=13351 Citypaper.com article] ] By the 1990s, VHS became a standard format for consumerrecording and viewing, after competing in a fierce format war with Sony Corporation's Betamaxand, to a much lesser extent, Philips' Video 2000, MCA's Laserdiscand RCA's Capacitance Electronic Disc.
VHS initially offered a longer playing time than the Betamax system, and it also had the advantage of a far less complex tape transport mechanism. Although VHS and Betamax were competing formats, several of VHS's critical technologies are licensed from
Sony. Early VHS machines could rewind and fast forward the tape considerably faster than a Betamax VCR because they unthreaded the tape from the playback heads before commencing any high-speed winding. Most newer VHS machines do not perform this unthreading step, as head-tape contact is no longer an impediment to fast winding, owing to improved engineering.
DVDs rentals surpassed VHS rentals in the US in
2003, surprising some industry officials. [http://washingtontimes.com/news/2003/jun/20/20030620-113258-1104r/] By 2006, most major film studios stopped releasing new movie titles in VHS format, opting for DVD-only releases. Many leading retailers have stopped selling pre-recorded movies on VHS, although VHS prerecorded cassettes are still popular with many collectors, mainly because there are thousands of titles that are still unavailable on DVD or other newer formats.
The VHS cassette is a 7 ⅜" wide, 4" deep, 1" thick (187 mm × 103 mm × 25 mm) plastic clamshell held together with 5 Philips head screws. The flip-up cover that protects the tape has a built-in latch with a push-in toggle on the right side, as seen in the Bottom View. The VHS cassette also includes an anti-despooling mechanism as seen in the Top View, several plastic parts near front label end of the cassette between the two spools. The spool brakes are released by a push-in lever within a 1/4" hole accessed from the bottom of the cassette, about 3/4" in from the edge label. There is a clear tape leader at both ends of the tape to provide an optical auto-stop for the VCR transport mechanism.
The recording medium is a ½
inch(12.7 mm) wide magnetic tapewound between two spools, allowing it to be slowly passed over the various playback and recording heads of the video cassette recorder. The tape speed is 3.335 cm/s for NTSC, 2.339 cm/s for PAL. A cassette holds a maximum of about 430 m of tape at the lowest acceptable tape thickness, giving a maximum playing time of about 3.5 hours for NTSC and 5 hours for PAL at "standard" (SP) quality. Other speeds include LP and EP/SLP which double and triple the recording time, for NTSC regions. These speed reductions cause a slight reduction in video quality (from 250 lines to 230 lines horizontal); also, tapes recorded at the lower speed often exhibit poor playback performance on recorders other than the one they were produced on. Because of this, commercial prerecorded tapes were almost always recorded in SP mode. As with almost all cassette-based videotape systems, VHS machines pull the tape from the cassette shell and wrap it around the head drum. VHS machines, in contrast to Betamaxand Beta's predecessor U-matic, use an M-loading system, also known as M-lacing, where the tape is drawn out by two threading posts and wrapped around the head drum (and other tape transportcomponents) in a shape roughly approximating the letter M.
VHS tapes have approximately 3 MHz of video bandwidth, which is achieved at a relatively low tape speed by the use of
helical scanrecording of a frequency modulated luminance (black and white) signal, with a down-converted "color under" chroma (color) signal recorded directly at the baseband. Because VHS is an analog system, VHS tapes represent video as a continuous stream of waves, in a manner similar to analog TV broadcasts. The waveform per scanline can reach about 160 waves at max, and contains 525 scanlines in NTSC(486 visible), or 625 lines in PAL(576 visible). In modern-day digital terminology, VHS is roughly equivalent to 320 pixels of horizontal resolution with a signal-to-noise ratio of the image at 43 dB.
JVC would counter 1985's SuperBeta with VHS HQ, or High Quality. The frequency modulation of the VHS luminance signal is limited to 3.1 megahertz which makes higher resolutions impossible, but an HQ branded deck includes luminance noise reduction, chroma noise reduction, white clip extension, and improved sharpness circuitry. The effect was to increase the apparent horizontal resolution of a VHS recording from 240 to 250 lines. The major VHS OEMs resisted HQ due to cost concerns, eventually resulting in JVC reducing the requirements for the HQ brand to "white clip extension plus one other improvement".
In 1987 JVC introduced the new format called Super VHS which extended the bandwidth to over 5 megahertz, yielding 420 lines horizontal (equivalent to 560x486 in digital terminology). For comparison DVD is 500 lines horizonal. The chroma resolution remained the same at approximately 0.6 megahertz bandwidth or 30 lines horizontal, as was common across analog tape standards from Umatic to VHS to ED Betamax. Even a live NTSC broadcast is limited to 120 chroma lines maximum. (For comparison DVD is 240 chroma horizontal.)
Audio Upgrade from Lo-Fi Monaural to Hi-Fi Stereo
In the original VHS format, audio was recorded unmodulated in a single linear track at the upper edge of the tape, which was limited in frequency response by the tape speed (about 100 Hz to 10 kHz with 42 dB
signal-to-noise ratioat SP). The vast majority of early home recorders only supported monaural for the linear audio track, even though studio film releases began to emerge in stereo from 1982. High-end consumer recorders with linear stereo playback also became available around this time, and these machines often offered other editing facilities such as "audio dubbing" and "video dubbing" functions. These would move the tape past the heads and keep the video unchanged while recording new linear audio or keep the linear audio unchanged while recording new video, respectively. This was useful, for example, for laying a song over a previously edited-together montage of short video clips that were the same total duration as that song. Without the dubbing features, this task would have required the tape to be copied to another tape which would cause generational loss.
Around 1985, "HiFi" VCRs emerged, adding higher-quality stereo audio tracks (20 Hz to 20 kHz with more than 70 dB S/N ratio) which are read and written by heads located on the same spinning drum that carries the video heads with frequency modulation. These audio tracks take advantage of "depth
multiplexing": since they use lower frequencies than the video, their magnetization signals penetrate deeper into the tape. When the video signal is written by the following video head, it erases and overwrites the audio signal at the surface of the tape, but leaves the deeper portion of the signal undisturbed. (PAL versions of Betamax use this same technique.) Some high-end VHS VCRs offered manual level control, which made the VHS HiFi format much more useful for high-quality audio-only recording. The excellent sound quality of HiFi VHS has gained it some popularity as an audio format in certain applications; in particular, ordinary home HiFi VCRs are sometimes used by home recordingenthusiasts as a handy and inexpensive medium for making high-quality stereo mixdowns and master recordings from multitrackaudio tape. However, because separate heads are used to record HiFi audio, advanced editing functions such as audio-only or video-only dubbing are impossible.
Tracking adjustment and index marking
Another linear "control" track, at the tape's lower edge, holds pulses that mark the beginning of every frame of video; these are used to fine-tune the tape speed during playback and to get the rotating heads exactly on their helical tracks rather than having them end up somewhere between two adjacent tracks (a feature called "tracking"). Since good tracking depends on the exact distance between the rotating drum and the fixed control/audio head reading the linear tracks, which usually varies by a couple of micrometers between machines due to manufacturing tolerances, most VCRs offer tracking adjustment, either manual or automatic, to correct such mismatches. The control can additionally hold "index marks". These are normally written at the beginning of each recording session, and can be found using the VCR's "index search" function: this will fast-wind forward or backward to the "n"th specified index mark, and resume playback from there. There was a time when higher-end VCRs provided functions for manually removing and adding these index marks — so that, for example, they coincide with the actual start of the program — but this feature has become hard to find in recent models.
Comparison to other media
Below is a list of modern-day, digital-style measurements (and traditional analog TV lines per picture height) for various media. The list only includes popular formats, not rare formats, and all values are approximate since the actual quality can vary machine-to-machine or tape-to-tape. For ease-of-comparison all values are for the NTSC system, and listed in ascending order from lowest quality to highest quality. (For PAL systems, replace "480" with "576".)
* 350×240 (250 lines): Video CD
* 330×480 (250 lines): Umatic, Betamax, VHS, Video8
* 400×480 (300 lines): Super Betamax, Betacam (professional)
* 440×480 (330 lines): Analog Broadcast
* 560×480 (420 lines): LaserDisc, Super VHS, Hi8
* 670×480 (500 lines): Enhanced Definition Betamax
* 720×480 (520 lines): NTSC DVD, NTSC MiniDV, Digital8, Digital Betacam (professional)
* 720×480 (400 lines): Widescreen DVD (anamorphic)
* 720×576 (576 lines): PAL DVD, PAL MiniDV
* 1280×720 (720 lines): D-VHS, HD DVD, Blu-ray Disc, HDV (miniDV)
* 1920×1080 (1080 lines): D-VHS, HD DVD, Blu-ray Disc, HDCAM SR (professional)
Super-VHS / Digital-VHS (high-definition) / ADAT
Several improved versions of VHS exist, most notably Super-VHS (S-VHS), an analog video standard with improved video bandwidth. S-VHS improved the luminance resolution to 400 horizontal per picture height (versus 250 for VHS/Beta and 500 for DVD). S-VHS made little impact on the home market, but gained dominance in the camcorder market due to its superior picture quality.
ADATformat provides the ability to record digital audio using S-VHS media.
The other improved standard, called Digital-VHS (D-VHS), records digital high definition video onto a VHS form factor tape. D-VHS can record up to 4 hours of ATSC Digital Television in 720p or 1080i formats using the fastest record mode (equivalent to VHS-SP), and up to 40 hours of standard definition video at slower speeds.
VHS-C / Super-VHS-C
Another variant is VHS-Compact (VHS-C), originally developed for portable VCRs in 1982, but ultimately finding success in palm-sized
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 longest tape available holds 40 minutes in SP mode and 120 minutes in EP mode.
Sony Betamax was unable to shrink that form any further, so instead they developed Video8/Hi8 which was in direct competition with the VHS-C/S-VHS-C format throughout the 80s, 90s, and 2000s. Ultimately neither format "won" and both continue to be sold in the low-end market (examples: JVC SXM38 and Sony TRV138). Super VHS-C camera recordings can be played back in standard VHS VCRs with SVHS-ET technology.
Use as PC backup devices
Devices have also been invented which directly connect a
personal computerto VHS tape recorders for use as a data backupdevice. Most notable of these devices was ArVid, widely used in Russiaand CIS states. Also available in the United Stateswere similar systems manufactured by Corvus, Videotrax, and Alpha Microsystems. Also available was "Backer" from Danmere Ltd.of England.Also HP develops a backup system that uses VHS tapes and store 5 GB in every tape.
W-VHScaters for analog high definition video. Discontinued and replaced by D-VHS.
There is also a JVC-designed component digital professional production format known as Digital-S, or officially under the name 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.
VHS can record and play back all varieties of analog television signals in existence at the time VHS was devised. However, a machine must be designed to record a given standard. Typically, a VHS machine can only handle signals of the country it was sold in. The following signal varieties exist in conventional VHS:
SECAM/625/25 (SECAM, French variety)
* MESECAM/625/25 (most other SECAM countries, notably the former Soviet Union and Middle East)
NTSC/525/30 (Most parts of North and South America, Japan, South Korea)
PAL/525/30 (i.e., PAL-M, Brazil)
PAL/576/25 (most of Western Europe, Australia, many parts of Asia such as China and India, some parts of South America such as Argentina and Uruguay, and Africa)
Since the 1990s, dual- and multi-standard VHS machines have become more and more common. These can handle VHS tapes of more than one standard. For example, regular VHS machines sold in Australia and Europe nowadays can typically handle PAL, MESECAM for record and playback, plus NTSC for playback only. Dedicated multistandard machines can usually handle all standards listed, some high end model can even convert a tape from one standard to another by using a built-in standards converter.
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. Likewise, S-VHS machines for the Brazilian market record in NTSC and convert to/from PAL-M.
A small number of VHS decks are able to decode closed captions on pre-recorded video cassettes. A smaller number still are able, additionally, to record
subtitlestransmitted with world standard teletextsignals (on pre-digital services), simultaneously with the associated program.
Both NTSC and PAL/SECAM 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.
In order to avoid confusion, manufacturers indicate the playing time in minutes that can be expected for the market the tape is sold in. It is perfectly possible to record and play back a blank T-XXX tape in a PAL machine or a blank E-XXX tape in an NTSC machine, but the resulting playing time will be different from that indicated. SP is Standard Play and LP is Long Play at 1/2 speed for both NTSC and PAL regions. EP/SLP designates Extended Play/Super Long Play at 1/3rd speed for NTSC regions. (PAL does not have an EP speed.)
* E-XXX indicates playing time in minutes for PAL or SECAM in SP speed.
* T-XXX indicates playing time in minutes for NTSC or PAL-M in SP speed.
VHS vs. Betamax
As mentioned, VHS was the winner of a protracted and somewhat bitter format war during the late 1970s and early 1980s against Sony's
Betamax was widely perceived at the time as the better format, as it offered a slightly higher horizontal resolution (250 lines vs. 240 lines in PAL & NTSC), lower video noise, and less luma-chroma crosstalk than VHS, and was marketed as providing pictures superior to VHS's, however the introduction of B-II speed (2-hour mode) to compete with VHS's 2-hour Standard Play mode, reduced Betamax's horizontal resolution to 240 lines. [cite web |author=Video Interchange |title=Video History |url=http://www.videointerchange.com/Video%20History.htm#BetaMax |accessdate=2007-08-20 ] The extension of VHS to VHS HQ produced 250 lines, so that overall a Betamax/VHS user could expect virtually identical luminance and chrominance resolution (~30 lines across), wherein the actual picture performance depended on other factors, including the condition and quality of the videotape, and the specific video recorder machine model.
Betamax held an early lead in the format war — but by 1981, U.S. Betamax sales had sunk to only 25% of all sales. [cite web |author=Helge Moulding |title=The Decline and Fall of Betamax |url=http://tafkac.org/products/beta_vs_vhs.html |accessdate=2007-08-20 ] VHS was gaining market share due to its longer tape time (in 1981, 9 hours maximum, compared to just 4 hours for Betamax in USA) and JVC's less strict licensing program. The longer tape time is sometimes cited as the defining factor in the format war, allowing consumers to record entire programs unattended (recording time between VHS and Betamax were similar in areas where VHS entered the market several years after introduction, such as the UK in 1978). Sony ultimately conceded the fight in 1988, bringing out a line of VHS VCRs of its own.
The format war and the "marketing over technology" claims have taken on a life of their own, and continue to be used as analogies in battles within the computer industry, including Apple vs.
IBM, Macintoshvs. PC, and HD DVDvs. Blu-ray Disc. Other formats such as 8 mm video cassettes and MiniDVhave emerged since the post-battle era, although these formats did little to erase VHS dominance in the home.
Both VHS and Betamax manufacturers created professional video formats built around the same cassette shells. The professional derivatives of VHS were M and then MII whereas the professional derivative of Betamax was
Betacamwhich has gone on to spawn digital variants. In a complete reversal of the domestic VHS-Betamax battle, in the professional arena the Beta format has been hugely successful, and the VHS derived formats became obsolete. Occasionally this causes some confusion, in that people believe that Betacam is a professional studio version of Betamax. In reality Betacam is only superficially similar. Although the tapes used may look the same,and the first generation Betacam tapes could be used for recording in Betamax machines, in Betacam they are run at a much higher linear speed, and the recording system is completely different. The same applied to the VHS based-professional formats.
Decline of VHS
In recent years, alternatives to tape-based technologies have appeared in the home recording market. The movement is to replace tape with more recent technologies, such as
optical discs, hard disks and flash-based storage systems. Altogether, these technologies are shrinking VHS's marketshare. The March 1997 introduction of the DVD format to American consumers was perhaps the greatest blow to the dominance of VHS. [http://www.washingtonpost.com/wp-dyn/content/article/2005/08/26/AR2005082600332.html "Parting Words For VHS Tapes, Soon to Be Gone With the Rewind"] , Washington Post, August 28 2005.]
Signs of VHS's decline come from two directions. First, electronic equipment manufacturers are downsizing their VHS recorder production lines. Both department and electronic "boutique" stores are also cutting down on the variety of VHS recorders they carry in-stock — especially the higher-end systems such as S-VHS recorders. In most stores, DVD players are now cheaper than VHS players.
Second, video content in VHS format is also slowly disappearing. The popularity of VHS in both for-sale and rental stores has fallen. Most retail stores have stopped selling new VHS movies alongside DVD versions.
Virtually only VHS/DVD combination units are available at retail stores in North America, but stand-alone 4 and 6 head
VCRs are still manufactured by LGand available for sale in Australia. The last standalone JVC VHS unit was reportedly produced in 2007. The final major Hollywood motion picture released on VHS was David Cronenberg's "A History of Violence". [http://citypaper.com/film/story.asp?id=13351]
Many TV stations choose to continue to use the VHS format for archiving programs and footage over other formats because of the tapes wide acceptance and availability at a lower cost than many other formats.Fact|date=September 2008 Because the VHS format is still widely accepted for personal use many stations choose to use it to easily copy and distribute tapes.Fact|date=September 2008
Although VHS is slowly declining, this dilemma does bring along with it opportunities, such as media conversion services, dual-deck and DVD/VCR combination systems, and even a lucrative re-sell market on auction and second-hand equipment sites.
Consumers still retain the technology as well. The Washington Post has noted that as of 2005, 94.5 million Americans still owned VHS format VCRs. In spite of the decline of pre-recorded VHS sales, blank, recordable VHS cassettes remain the most popular means of recording live television programming in households around the world.
Optical disc-based technologies
DVD-Videoformat was introduced first, in 1996, in Japan, to the United States in March 1997 ("Test Marketed"), mid-late 1998 in Europe and early 1999 in Australia.
Despite DVD's better quality (500 lines versus 250 lines horizontal resolution), VHS is still widely used in home recording of television programs, due to the large installed base and the lower cost of VHS recorders and tape. The commercial success of DVD recording and re-writing has been hindered by a number of factors including:
*A reputation for being temperamental and occasionally unreliable, as well as the risk caused by scratches and hairline cracks.
*Shorter recording time: Up to 6 hours on a single-layer disc (with high compression) versus 10.5 (NTSC) or 10 (PAL/SECAM) hours on a T-210 VHS-EP tape.
High-capacity digital recording technologies
High-capacity digital recording systems are also gaining in popularity with home users. These types of systems come in several form factors:
* Hard disk-based
* Hard disk/
optical disccombination set-top boxes
* Personal computer-based
media centerHard disk-based systems include TiVoas well as other digital video recorder (DVR) offerings. These types of systems provide users with virtually a no-maintenance solution for capturing video content. VHS and other cartridge solutions require physical handling of the media, as well as upkeep duties such as cleaning of the heads. Unlike both cartridge-based and optical disc-based systems, hard disk-based systems allow for many hours of recording without physical maintenance. For example, a 120 GB system recording at an extended recording rate (XP) of 9,800 kbit/s MPEG-2can record over 25 hours of video content. Just like VHS, the latest optical disc technologies must still rely on tangibles, such as blank discs.
PC-based media centers are also becoming popular in homes. PCs can serve the same features as a DVR set-top box, but also add a usable operating environment for other tasks such as electronic mail and surfing the Internet. A media center may be the better solution for the technical-savvy consumer who is looking for a system he can regularly upgrade, such as disk capacity and software.
VHS in popular culture
*Toei produced a motion picture called "
Hi wa Mata Noboru" (2002), starring Toshiyuki Nishida. Toshiyuki plays the role of Shizuo Kagaya, the head of the video department at Victor. In the process of developing a home VCR, he basically invents VHS. Although the movie is based on a true story, it was produced purely for entertainment and not as a documentary, which explains some of the over-dramatizations of its characters and events. Several important events are covered, such as the unification of VCR standards by Japan's Ministry of Trade, who favored Sony's Betamaxformat, and the importance in Victor bringing Matsushita on-board as a partner to build VHS units.
2008 film" Be Kind Rewind" concerns a video rental store employee ( Mos Def) who finds that his friend ( Jack Black) has accidentally wiped all the video cassettes in the store, and they resort to acting out the films in front of a video camera to avoid disappointing customers. The film features many references to the format, and even includes a VHS tape on one of the posters.
* The finishing track of
Radiohead's 2007 album " In Rainbows", Videotape, concerns its usage in recording memories.
* In the late 1980s, Exabyte pioneered the adaptation of VHS tape as a
digital computerbackup-storage medium. Eventually, Radio Shack marketed a computer data backup device at the retail level based on the same concept. Other, similar devices have been created and marketed since for various platforms.
fontused in the VHS logo is called "Lee". It was created in 1972 by Leo Weiszfor Visual Graphics Corporation(VGC).
* VHS is called "half-inch" by some in the film and video production industry, to differentiate it from "three-quarter inch" (
= References =
* [http://news.bbc.co.uk/1/hi/business/4031223.stm BBC News article: Death of video recorder in sight]
* [http://vhs.myfreeforum.org/ Forum for VHS fanatics]
* [http://electronics.howstuffworks.com/vcr.htm HowStuffWorks: How VCRs work]
* [http://www.iasforensics.com/VHS1.jpgMagnetic Image of VHS tape recording / Image And Sound Forensics(TM)]
* [http://www.geocities.com/videoholic2000/RiseandFall.htm The Rise and Fall of Beta] by Marc Wielage & Rod Woodcock
* [http://www.totalrewind.org The 'Total Rewind' VCR museum] covering the history of VHS and other vintage formats
* [http://www.high-techproductions.com/video1.htm Video tape time comparisons for NTSC vs. PAL]
* [http://youtube.com/watch?v=z5DH8epwsEQ Youtube.com]
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