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At that time, the expensive devices were used only in professional environments such as television studios and medical imaging fluoroscopy. In the s, videotape entered home use, creating the home video industry and changing the economics of the motion picture and television businesses.
The television industry viewed videocassette recorders VCRs as having the power to disrupt their business, while television users viewed the VCR as a means to take control of their viewing experiences by allowing them to watch programming repeatedly and at more convenient times. In the later s and early s, there was a format war in the home video industry.
Two of the standards, VHS and Betamax , received the most media exposure. The earliest of these formats, LaserDisc , was not widely adopted across Europe, but was hugely popular in Japan and a minor success in the United States. Kenjiro Takayanagi , a television broadcasting pioneer then working for JVC as its vice president, saw the need for his company to produce VTRs for the Japanese market, and at a more affordable price. In , JVC developed a two-head video tape recorder, and by a color version for professional broadcasting.
In , JVC collaborated with Sony Corporation and Matsushita Electric Matsushita was then parent company of Panasonic and is now known by that name, also majority stockholder of JVC until in building a video recording standard for the Japanese consumer. The U-matic format was successful in businesses and some broadcast applications for television stations such as electronic news-gathering , but due to cost and limited recording time very few of the machines were sold for home use.
Soon after, Sony and Matsushita broke away from the collaboration effort, in order to work on video recording formats of their own. Sony started working on Betamax , while Matsushita started working on VX. Sony and Matsushita also produced U-matic systems of their own. In early , the commercial video recording industry in Japan took a financial hit. However, despite the lack of funding, Takano and Shiraishi continued to work on the project in secret.
By , the two engineers had produced a functional prototype. In , the Japanese Ministry of International Trade and Industry MITI , desiring to avoid consumer confusion , attempted to force the Japanese video industry to standardize on just one home video recording format.
With this prototype, Sony persuaded the MITI to adopt Betamax as the standard, and allow it to license the technology to other companies. JVC believed that an open standard , with the format shared among competitors without licensing the technology, was better for the consumer. Matsushita also regarded Betamax's one-hour recording time limit as a disadvantage.
However, the collaboration of JVC and its partners was much stronger, and eventually led the MITI to drop its push for an industry standard. Sony's Betamax competed with VHS throughout the late s and into the s see Videotape format war. Betamax's major advantages were its smaller cassette size, theoretical higher video quality, and earlier availability, but its shorter recording time proved to be a major shortcoming.
Originally, Beta I machines using the NTSC television standard were able to record one hour of programming at their standard tape speed of 1. Betamax's smaller-sized cassette limited the size of the reel of tape, and could not compete with VHS's two-hour capability by extending the tape length. Additionally, VHS had a "far less complex tape transport mechanism" than Betamax, and VHS machines were faster at rewinding and fast-forwarding than their Sony counterparts.
It was also capable of recording four hours in LP long play mode. The flip-up cover, which allows players and recorders to access the tape, has a latch on the right side, with a push-in toggle to release it bottom view image. The cassette has an anti-despooling mechanism, consisting of several plastic parts between the spools, near the front of the cassette white and black in the top view.
The spool latches are released by a push-in lever within a 6. There is a clear tape leader at both ends of the tape to provide an optical auto-stop for the VCR transport mechanism. In the VCR, a light source is inserted into the cassette through the circular hole in the center of the underside, and two photodiodes are to the left and right sides of where the tape exits the cassette.
When the clear tape reaches one of these, enough light will pass through the tape to the photodiode to trigger the stop function; some VCRs automatically rewind the tape when the trailing end is detected. Early VCRs used an incandescent bulb as the light source: when the bulb failed, the VCR would act as if a tape were present when the machine was empty, or would detect the blown bulb and completely stop functioning.
Later designs use an infrared LED , which has a much longer life. The recording medium is a Mylar [32] magnetic tape , The tape speed for "Standard Play" mode see below is 3. The tape length for a T VHS cassette is As with almost all cassette-based videotape systems, VHS machines pull the tape out from the cassette shell and wrap it around the inclined head drum which rotates at 1, rpm in NTSC machines [34] and at 1, rpm for PAL , one complete rotation of the head corresponding to one video frame.
VHS uses an "M-loading" system, also known as M-lacing, where the tape is drawn out by two threading posts and wrapped around more than degrees of the head drum and also other tape transport components in a shape roughly approximating the letter M. More frequently however, VHS tapes are thicker than the required minimum to avoid complications such as jams or tears in the tape.
Because of the nature of recording diagonally from a spinning drum, the actual write speed of the video heads does not get slower when the tape speed is reduced. Instead, the video tracks become narrower and are packed closer together. This results in noisier playback that can be more difficult to track correctly: The effect of subtle misalignment is magnified for the narrower tracks.
The heads for linear audio are not on the spinning drum, so for them, tape speed from one reel to the other is the same as the speed of the heads across the tape. This is widely considered inadequate for anything but basic voice playback, and was a major liability for VHS-C camcorders that encouraged use of the EP speed. Color depth deteriorates significantly at lower speeds in PAL: often, a color image on a PAL tape recorded at low speed is displayed only in monochrome, or with intermittent color, when playback is paused.
The tape speeds are different too, so the playing time for any given cassette will vary between the systems. As VHS was designed to facilitate recording from various sources, including television broadcasts or other VCR units, content producers quickly found that home users were able to use the devices to copy videos from one tape to another.
Despite generation loss , [36] this was regarded as a widespread problem, which members of the Motion Picture Association of America MPAA claimed caused them great financial losses. The most popular method was Analog Protection System , better known simply as Macrovision , produced by a company of the same name.
The technology is applied to over million videocassettes annually and is used by every MPAA movie studio on some or all of their videocassette releases. Over commercial duplication facilities around the world are equipped to supply Macrovision videocassette copy protection to rights owners The system was first used in copyrighted movies beginning with the film The Cotton Club. Macrovision copy protection saw refinement throughout its years, but has always worked by essentially introducing deliberate errors into a protected VHS tape's output video stream.
These errors in the output video stream are ignored by most televisions, but will interfere with re-recording of programming by a second VCR. The first version of Macrovision introduces high signal levels during the vertical blanking interval , which occurs between the video fields.
These high levels confuse the automatic gain control circuit in most VHS VCRs, leading to varying brightness levels in an output video, but are ignored by the TV as they are out of the frame-display period. Level III protection added additional colorstriping techniques to further degrade the image. These protection methods worked well to defeat analog-to-analog copying by VCRs of the time.
Products capable of digital video recording are mandated by law to include features which detect Macrovision encoding of input analog streams, and reject copying of the video. The erase head is fed by a high level, high frequency AC signal that overwrites any previous recording on the tape.
The tape path then carries the tape around the spinning head drum, wrapping it around a little more than degrees called the omega transport system in a helical fashion, assisted by the slanted tape guides. The head rotates constantly at [a] Two tape heads are mounted on the cylindrical surface of the drum, degrees apart from each other, so that the two heads "take turns" in recording. The rotation of the inclined head drum, combined with the relatively slow movement of the tape, results in each head recording a track oriented at a diagonal with respect to the length of the tape, with the heads moving across the tape at speeds higher than what would otherwise be possible.
This is referred to as helical scan recording. The heads on the drum move across the tape at a writing speed of 4. To maximize the use of the tape, the video tracks are recorded very close together to each other. To reduce crosstalk between adjacent tracks on playback, an azimuth recording method is used: The gaps of the two heads are not aligned exactly with the track path. Instead, one head is angled at plus seven degrees from the track, and the other at minus seven degrees.
This results, during playback, in destructive interference of the signal from the tracks on either side of the one being played. One tape head records an entire picture field. The original VHS specification had only two video heads. When the EP recording speed was introduced, the thickness of these heads was reduced to accommodate the narrower tracks.
However, this subtly reduced the quality of the SP speed, and dramatically lowered the quality of freeze frame and high speed search. Later models implemented both wide and narrow heads, and could use all four during pause and shuttle modes to further improve quality.
Camcorders using the miniaturized drum required twice as many heads to complete any given task. This almost always meant four heads on the miniaturized drum with performance similar to a two head VCR with a full sized drum.
No attempt was made to record Hi-Fi audio with such devices, as this would require an additional four heads to work. The high tape-to-head speed created by the rotating head results in a far higher bandwidth than could be practically achieved with a stationary head. The luminance black and white portion of the video is recorded as a frequency modulated , with a down-converted " color under " chroma color signal recorded directly at the baseband. Each helical track contains a single field 'even' or 'odd' field, equivalent to half a frame, see interlaced video encoded as an analog raster scan , similar to analog TV broadcasts.
The horizontal resolution is lines per picture height, or about lines across a scan line, and the vertical resolution the number of scan lines is the same as the respective analog TV standard for PAL or for NTSC ; usually, somewhat fewer scan lines are actually visible due to overscan.
The frequency modulation of the VHS luminance signal is limited to 3 megahertz, which makes higher resolutions technically impossible even with the highest-quality recording heads and tape materials, 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 to analog equivalent to pixels from left-to-right, in digital terminology. S-VHS was designed for higher resolution, but failed to gain popularity outside Japan because of the high costs of the machines and tapes.
After leaving the head drum, the tape passes over the stationary audio and control head. This records a control track at the bottom edge of the tape, and one or two linear audio tracks along the top edge. In the original VHS specification, audio was recorded as baseband in a single linear track, at the upper edge of the tape, similar to how an audio compact cassette operates. The recorded frequency range was dependent on the linear tape speed. The signal-to-noise ratio SNR was an acceptable 42 dB.
S-VHS tapes can give better audio and video quality, because the tapes are designed to have almost twice the bandwidth of VHS at the same speed. Sound cannot be recorded on a VHS tape without recording a video signal, even in the audio dubbing mode. If there is no video signal to the VCR input, most VCRs will record black video and generate a control track while the sound is being recorded.
Some early VCRs record audio without a control track signal; this is of little use, because the absence of a signal from the control track means that the linear tape speed is irregular during playback. More sophisticated VCRs offer stereo audio recording and playback. Linear stereo fits two independent channels in the same space as the original mono audiotrack. While this approach preserves acceptable backward compatibility with monoaural audio heads, the splitting of the audio track degrades the audio's signal-to-noise ratio, causing objectionable tape hiss at normal listening volume.
This dynamically boosts the high frequencies of the audio program on the recorded medium, improving its signal strength relative to the tape's background noise floor, then attenuates the high frequencies during playback. Dolby-encoded program material exhibits a high-frequency emphasis when played on non-Hi-Fi VCRs that are not equipped with the matching Dolby Noise Reduction decoder, although this may actually improve the sound quality of non-Hi-Fi VCRs, especially at the slower recording speeds.
High-end consumer recorders take advantage of the linear nature of the audio track, as the audio track could be erased and recorded without disturbing the video portion of the recorded signal. Hence, "audio dubbing" and "video dubbing", where either the audio or video are re-recorded on tape without disturbing the other , were supported features on prosumer linear video editing -decks.
Without dubbing capability, an audio or video edit could not be done in-place on master cassette, and requires the editing output be captured to another tape, incurring generational loss. Studio film releases began to emerge with linear stereo audiotracks in From that point onward nearly every home video release by Hollywood featured a Dolby-encoded linear stereo audiotrack.
However, linear stereo was never popular with equipment makers or consumers. 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, so that the high speed rotating heads remained exactly on their helical tracks rather than somewhere between two adjacent tracks known as " tracking ".
The control track is also used to hold index marks , which were 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.
At times, higher-end VCRs provided functions for the user to manually add and remove these marks. By the late s, some high-end VCRs offered more sophisticated indexing. For example, Panasonic's Tape Library system assigned an ID number to each cassette, and logged recording information channel, date, time and optional program title entered by the user both on the cassette and in the VCR's memory for up to recordings with titles.
Both VHS Hi-Fi and Betamax Hi-Fi delivered flat full-range frequency response 20 Hz to 20 kHz , excellent 70 dB signal-to-noise ratio in consumer space, second only to the compact disc , dynamic range of 90 dB, and professional audio -grade channel separation more than 70 dB.
VHS Hi-Fi audio is achieved by using audio frequency modulation AFM , modulating the two stereo channels L, R on two different frequency-modulated carriers and embedding the combined modulated audio signal pair into the video signal. To avoid crosstalk and interference from the primary video carrier, VHS's implementation of AFM relied on a form of magnetic recording called depth multiplexing.
The modulated audio carrier pair was placed in the hitherto-unused frequency range between the luminance and the color carrier below 1. Subsequently, the video head erases and re-records the video signal combined luminance and color signal over the same tape surface, but the video signal's higher center frequency results in a shallower magnetization of the tape, allowing both the video and residual AFM audio signal to coexist on tape.
During playback, VHS Hi-Fi recovers the depth-recorded AFM signal by subtracting the audio head's signal which contains the AFM signal contaminated by a weak image of the video signal from the video head's signal which contains only the video signal , then demodulates the left and right audio channels from their respective frequency carriers.
The result of the complex process was audio of high fidelity, which was uniformly solid across all tape-speeds EP, LP or SP. Since JVC had gone through the complexity of ensuring Hi-Fi's backward compatibility with non-Hi-Fi VCRs, virtually all studio home video releases produced after this time contained Hi-Fi audio tracks, in addition to the linear audio track.
The sound quality of Hi-Fi VHS stereo is comparable to some extent to the quality of CD audio, particularly when recordings were made on high-end or professional VHS machines that have a manual audio recording level control. This high quality compared to other consumer audio recording formats such as compact cassette attracted the attention of amateur and hobbyist recording artists.
Home recording enthusiasts occasionally recorded high quality stereo mixdowns and master recordings from multitrack audio tape onto consumer-level Hi-Fi VCRs. However, because the VHS Hi-Fi recording process is intertwined with the VCR's video-recording function, advanced editing functions such as audio-only or video-only dubbing are impossible. A short-lived alternative to the hifi feature for recording mixdowns of hobbyist audio-only projects was a PCM adaptor so that high-bandwidth digital video could use a grid of black-and-white dots on an analog video carrier to give pro-grade digital sounds though DAT tapes made this obsolete.
Some VHS decks also had a "simulcast" switch, allowing users to record an external audio input along with off-air pictures. Some televised concerts offered a stereo simulcast soundtrack on FM radio and as such, events like Live Aid were recorded by thousands of people with a full stereo soundtrack despite the fact that stereo TV broadcasts were some years off especially in regions that adopted NICAM.
Other examples of this included network television shows such as Friday Night Videos and MTV for its first few years in existence. Likewise, some countries, most notably South Africa , provided alternate language audio tracks for TV programming through an FM radio simulcast. The considerable complexity and additional hardware limited VHS Hi-Fi to high-end decks for many years.
Even then, most customers were unaware of its significance and merely enjoyed the better audio performance of the newer decks. Due to the path followed by the video and Hi-Fi audio heads being striped and discontinuous�unlike that of the linear audio track�head-switching is required to provide a continuous audio signal. While the video signal can easily hide the head-switching point in the invisible vertical retrace section of the signal, so that the exact switching point is not very important, the same is obviously not possible with a continuous audio signal that has no inaudible sections.
Hi-Fi audio is thus dependent on a much more exact alignment of the head switching point than is required for non-HiFi VHS machines. Misalignments may lead to imperfect joining of the signal, resulting in low-pitched buzzing.
Another issue that made VHS Hi-Fi imperfect for music is the inaccurate reproduction of levels softer and louder which are not re-created as the original source. The audio system both linear and AFM is the same. S-VHS made little impact on the home market, but gained dominance in the camcorder market due to its superior picture quality. 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 adapter is mechanical, although early examples were motorized, with a battery.
It has an internal hub to engage with the VCR mechanism in the location of a normal full-size tape hub, driving the gearing on the VHS-C cassette.
Also, when a VHS-C cassette is inserted into the adapter, a small swing-arm pulls the tape out of the miniature cassette to span the standard tape path distance between the guide rollers of a full-size tape. This allows the tape from the miniature cassette to use the same loading mechanism as that from the standard cassette. Ultimately neither format "won" and both have been superseded by digital high definition equipment. 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 Sel-Sync pre-read for video editing. It has now been superseded by high definition formats.
These devices served the sole purpose of rewinding VHS tapes. Proponents of the rewinders argued that the use of the rewind function on the standard VHS player would lead to wear and tear of the transport mechanism. The rewinder would rewind the tapes smoothly and also normally do so at a faster rate than the standard rewind function on VHS players. However, some rewinder brands did have some frequent abrupt stops, which occasionally led to tape damage.
Some devices were marketed which allowed a personal computer to use a VHS recorder as a data backup device. 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 using the same standard as the country it was sold in. Since the s, dual and multi-standard VHS machines, able to handle a variety of VHS-supported video standards, became more common. Dedicated multi-standard machines can usually handle all standards listed, and some high-end models could convert the content of a tape from one standard to another on the fly during playback by using a built-in standards converter.
A small number of VHS decks are able to decode closed captions on video cassettes before sending the full signal to the set with the captions. A smaller number still are able, additionally, to record subtitles transmitted with world standard teletext signals on pre-digital services , simultaneously with the associated program. S-VHS has a sufficient resolution to record teletext signals with relatively few errors, [55] although for some years now it has been possible to recover teletext pages and even complete "page carousels" from regular VHS recordings using non-real-time computer processing.
VHS was popular for long-form content, such as feature films or documentaries, as well as short-play content, such as music videos, in-store videos, teaching videos, distribution of lectures and talks, and demonstrations. VHS instruction tapes were sometimes included with various products and services, including exercise equipment, kitchen appliances, and computer software. VHS was the winner of a protracted and somewhat bitter format war during the late s and early s against Sony's Betamax format as well as other formats of the time.
Betamax was widely perceived at the time as the better format, as the cassette was smaller in size, and Betamax offered slightly better video quality than VHS � it had lower video noise, less luma-chroma crosstalk , and was marketed as providing pictures superior to those of VHS. However, the sticking point for both consumers and potential licensing partners of Betamax was the total recording time.
Very high-end Betamax machines still supported recording in the Beta I mode and some in an even higher resolution Beta Is Beta I Super HiBand mode, but at a maximum single-cassette run time of [with an L cassette]. Because Betamax was released more than a year before VHS, it held an early lead in the format war.
However, by , United States' Betamax sales had dipped to only percent of all sales. Some, including Sony's founder Akio Morita, say that it was due to Sony's licensing strategy with other manufacturers, which consistently kept the overall cost for a unit higher than a VHS unit, and that JVC allowed other manufacturers to produce VHS units license-free, thereby keeping costs lower.
Sony also introduced two machines the VP videocassette player and the VO, also called the VO video-cassette recorder to use the new tapes. In , Philips developed a home video cassette format specially made for a TV station in and available on the consumer market in Philips named this format " Video Cassette Recording " although it is also referred to as "N", after the first recorder's model number.
The industry boomed in the s as more and more customers bought VCRs. Betamax was first to market in November , and was argued by many to be technically more sophisticated in recording quality. In the early s US film companies fought to suppress the VCR in the consumer market, citing concerns about copyright violations.
In Congressional hearings, Motion Picture Association of America head Jack Valenti decried the "savagery and the ravages of this machine" and likened its effect on the film industry and the American public to the Boston strangler :. I say to you that the VCR is to the American film producer and the American public as the Boston strangler is to the woman home alone. In the case Sony Corp. Universal City Studios, Inc.
Subsequently the film companies found that making and selling video recordings of their productions had become a major income source. The video cassette recorder is sensitive to changes in temperature and humidity. If the machine or tape was moved from a hot to a colder environment there could be condensation of moisture on the internal parts, such as the rotating video head drum.
Some later models were equipped with a dew warning which would prevent operation in this case, but it could not detect moisture on the surface of a tape. The presence of moisture between the tape and the rotating head drum increases friction which prevents correct operation and can cause damage to both the recording device and the tape. In extreme cases, if the dew sensor fails to function and stop the video recorder, moisture can cause the tape to stick to the spinning video head.
This can pull a large amount of tape from the cassette before the head drum stops spinning. The tape will be extensively damaged, the video heads will often become clogged, and the mechanism may be unable to eject the cassette.
The dew sensor itself is mounted very close to the video head drum. Contrary to how one might expect this to behave, the sensor increases its resistance when moisture is present. Poor contacts on the sensor can therefore be a cause of random dew sensor warnings. Magnetic tapes could be mechanically damaged when ejected from the machine due to moisture or other problems.
Rubber drive belts and rollers hardened with age, causing malfunctions. Due to the path followed by the video and Hi-Fi audio heads being striped and discontinuous�unlike that of the linear audio track�head-switching is required to provide a continuous audio signal.
While the video signal can easily hide the head-switching point in the invisible vertical retrace section of the signal, so that the exact switching point is not very important, the same is obviously not possible with a continuous audio signal that has no inaudible sections. Hi-Fi audio is thus dependent on a much more exact alignment of the head switching point than is required for non-HiFi VHS machines. Misalignments may lead to imperfect joining of the signal, resulting in low-pitched buzzing.
Most camcorders produced in the 20th century also feature an integrated VCR. Generally, they include neither a timer nor a TV tuner. In the 21st century, digital recording became the norm while videocassette tapes dwindled away gradually; tapeless camcorders use other storage media such as DVDs, or internal flash memory , hard drive , and SD card. Jump to content Navigation. Help Learn to edit Community portal Recent changes Upload file.
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Article Talk. Read Edit View history. More Read Edit View history. Device designed to record and playback content stored on videocassettes, most commonly VHS. For other uses, see VCR disambiguation. This article has multiple issues. Please help improve it or discuss these issues on the talk page. Learn how and when to remove these template messages. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources.
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