اين محصول را شرکت سونى توليد کرد که رقيب وي.اچ.اس. شد. بتامکس هرگز در انگلستان متداول نشد، ولى در ساير کشورها بهکار مىرفت. بتامکس مانند وي.اچ.اس. در پخش برنامه کاربرد ندارد ولى با سيستم اف.۱ پي.سي.ام. (F1 PCM)
سونى بهعنوان ضبط صوت ديجيتالى اوليه مورد استفاده قرار گرفت.
Common tape lengths
||60 min (1 h)
||60 min (1 h)
||90 min (1:30 h)
||65 min (1:05 h)
||90 min (1:30 h)
||135 (2:15 h)
||96 min (1:36 h)
||60 min (1 h)
||120 min (2 h)
||180 min (3 h)
||130 min (2:10 h)
||90 min (1:30 h)
||180 min (3 h)
||270 min (4:30 h)
||195 min (3:15 h)
||100 min (1:40 h)
||200 min (3:20 h)
||300 min (5 h)
||216 min (3:36 h)
Betamax (also called Beta, as in its logo) is a consumer-level analog-recording and cassette format of magnetic tape for video. It was developed by Sony and was released in Japan on May 10, 1975. The first Betamax introduced in the United States was the LV-1901 console, which included a 19-inch (48 cm) color monitor, and appeared in stores in early November 1975. The cassettes contain 0.50-inch-wide (12.7 mm) videotape in a design similar to that of the earlier, professional 0.75-inch-wide (19 mm), U-matic format. Betamax is obsolete, having lost the videotape format war to VHS. Production of Betamax recorders ceased in 2002; new Betamax cassettes were available until March 2016, when Sony stopped making and selling them.
Like the rival videotape format VHS (introduced in Japan by JVC in October 1976 and in the United States by RCA in August 1977), Betamax has no guard band and uses azimuth recording to reduce crosstalk. According to Sony's history webpages, the name had a double meaning: beta is the Japanese word used to describe the way in which signals are recorded on the tape; and the shape of the lowercase Greek letter beta (β) resembles the course of the tape through the transport. The suffix -max, from the word "maximum", was added to suggest greatness. In 1977, Sony issued the first long-play Betamax VCR, the SL-8200. This VCR had two recording speeds: normal, and the newer half speed. This provided two hours' recording on the L-500 Beta videocassette. The SL-8200 was to compete against the VHS VCRs, which allowed up to 4, and later 6 and 8, hours of recording on one cassette.
Sanyo marketed a version as Betacord, which also was casually called "Beta". In addition to Sony and Sanyo, Beta-format video recorders were manufactured and sold by Toshiba, Pioneer, Murphy, Aiwa, and NEC. The Zenith Electronics Corporation and WEGA Corporations contracted with Sony to produce VCRs for their product lines. The department stores Sears (in the United States and Canada) and Quelle (in Germany) sold Beta-format VCRs under their house brands, as did the RadioShack chain of electronic stores. Betamax and VHS competed in a fierce format war, which saw VHS win in most markets.
Home and professional recording
One other major consequence of the Betamax technology's introduction to the U.S. was the lawsuit Sony Corp. v. Universal City Studios (1984, the "Betamax case"), with the U.S. Supreme Court determining home videotaping to be legal in the United States, wherein home videotape cassette recorders were a legal technology since they had substantial noninfringing uses. This precedent was later invoked in MGM v. Grokster (2005), where the high court agreed that the same "substantial noninfringing uses" standard applies to authors and vendors of peer-to-peer file sharing software (notably excepting those who "actively induce" copyright infringement through "purposeful, culpable expression and conduct").
Three Sony Betamax VCRs built for the American market. Top to bottom: SL-2000 portable with TT-2000 tuner/timer "Base Station" (1982); SL-HF 300 Betamax HiFi unit (1984); SL-HF 360 SuperBeta HiFi unit (1988).
A rare Japanese market Betamax TV/VCR combo, the Model SL-MV1.
The early-form Betacam tapes (left) are interchangeable with Betamax (right), though the recordings are not.
Betamax tapes on display at a museum.
For the professional and broadcast video industry, Sony derived Betacam from Betamax. Released in 1982, Betacam became the most widely used videotape format in ENG (electronic news gathering), replacing the .75 in (19 mm) wide U-matic tape format. Betacam and Betamax are similar in some ways: they use the same videocassette shape, use the same oxide tape formulation with the same coercivity, and record linear audio tracks in the same location of the tape. But in the key area of video recording, Betacam and Betamax are completely different. (For details, see the Betacam article.)
Sony also offered a range of industrial Betamax products, a Beta I-only format for industrial and institutional users. These were aimed at the same market as U-Matic equipment, but were cheaper and smaller. The arrival of Betacam reduced the demand for both industrial Beta and U-Matic equipment. 
Betamax also had a significant part to play in the music recording industry, when Sony introduced its PCM (Pulse Code Modulation) digital recording system as an encoding box/PCM adaptor that connected to a Betamax recorder. The Sony PCM-F1 adaptor was sold with a companion Betamax VCR SL-2000 as a portable digital audio recording system. Many recording engineers used this system in the 1980s and 1990s to make their first digital master recordings.
Initially, Sony was able to tout several Betamax-only features, such as BetaScan—a high speed picture search in either direction—and BetaSkipScan, a technique that allowed the operator to see where he was on the tape by pressing the FF key (or REW, if in that mode): the transport would switch into the BetaScan mode until the key was released. This feature is discussed in more detail on Peep Search. Sony believed that the M-Load transports used by VHS machines made copying these trick modes impossible. BetaSkipScan (Peep Search) is now available on miniature M-load formats, but even Sony was unable to fully replicate this on VHS. BetaScan was originally called "Videola" until the company that made the Moviola threatened legal action.
Sony would also sell a BetaPak, a small deck designed to be used with a camera. Concerned with the need for several pieces and cables to connect them, an integrated camera/recorder was designed, which Sony dubbed a "Camcorder"; the result was Betamovie. Betamovie used the standard-size cassette, but with a modified transport. The tape was wrapped 300° around a smaller, 44.671 mm (1.7587 in)-diameter head drum, with a single dual-azimuth head to write the video tracks. For playback, the tape would be inserted into a Beta-format deck. Due to the different geometry and writing techniques employed, playback within the camcorder was not feasible. SuperBeta and industrial Betamovie camcorders would also be sold by Sony.
HiFi audio upgrade
In June 1983, Sony introduced high fidelity audio to videotape as Beta Hi-Fi. For NTSC, Beta HiFi worked by placing a pair of FM carriers between the chroma (C) and luminance (Y) carriers, a process known as frequency multiplexing. Each head had a specific pair of carriers; in total, four individual channels were employed. Head A recorded its hi-fi carriers at 1.38(L) and 1.68(R) MHz, and the B head employed 1.53 and 1.83 MHz. The result was audio with an 80 dB dynamic range, with less than 0.005% wow and flutter.
Prior to the introduction of Beta Hi-Fi, Sony shifted the Y carrier up by 400 kHz to make room for the four FM carriers that would be needed for Beta Hi-Fi. All Beta machines incorporated this change, plus the ability to hunt for a lower frequency pre-AFM Y carrier. Sony incorporated an "antihunt" circuit, to stop the machine hunting for a Y carrier that wasn't there.
Some Sony NTSC models were marketed as "Hi-Fi Ready" (with an SL-HFR prefix to the model's number instead of the usual SL or SL-HF). These Betamax decks looked like a regular Betamax model, except for a special 28-pin connector on the rear. If the user desired a Beta Hi-Fi model but lacked the funds at the time, he could purchase an "SL-HFRxx" and at a later date purchase the separate Hi-Fi Processor. Sony offered two outboard Beta Hi-Fi processors, the HFP-100 and HFP-200. They were identical except that the HFP-200 was capable of multi-channel TV sound, with the word "stereocast" printed after the Beta Hi-Fi logo. This was possible because unlike a VHS Hi-Fi deck, an NTSC Betamax didn't need an extra pair of heads. The HFP-x00 would generate the needed carriers which would be recorded by the attached deck, and during playback the AFM carriers would be passed to the HFP-x00. They also had a small "fine tracking" control on the rear panel for difficult tapes.
For PAL, however, the bandwidth between the chroma and luminance carriers was not sufficient to allow additional FM carriers, so depth multiplexing was employed, wherein the audio track would be recorded in the same way that the video track was. The lower-frequency audio track was written first by a dedicated head, and the video track recorded on top by the video head. The head disk had an extra pair of audio-only heads with a different azimuth, positioned slightly ahead of the regular video heads, for this purpose.
Sony was confident that VHS could not achieve the same audio performance feat as Beta Hi-Fi. However, to the chagrin of Sony, JVC did develop a VHS hi-fi system on the principle of depth multiplexing approximately a year after the first Beta Hi-Fi VCR, the SL-5200, was introduced by Sony. Despite initial praise as providing "CD sound quality", both Beta Hi-Fi and VHS HiFi suffered from "carrier buzz", where high frequency information bled into the audio carriers, creating momentary "buzzing" and other audio flaws. Both systems also used companding noise-reduction systems, which could create "pumping" artifacts under some conditions. Both formats also suffered from interchange problems, where tapes made on one machine did not always play back well on other machines. When this happened and if the artifacts became too distracting, users were forced to revert to the old linear soundtrack.
New standards: SuperBetamax and Extended Definition Betamax
In early 1985, Sony would introduce a new feature, High Band or SuperBeta, by again shifting the Y carrier—this time by 800 kHz. This improved the bandwidth available to the Y sideband and increased the horizontal resolution from 240 to 290 lines on a regular-grade Betamax cassette. Since over-the-antenna and cable signals were only 300–330 lines resolution, SuperBeta could make a nearly identical copy of live television. However, the chroma resolution still remained relatively poor, limited to just under 0.4 MHz or approximately 30 lines resolution, whereas live broadcast chrominance resolution was over 100 lines. The heads were also narrowed to 29 μm to reduce crosstalk, with a narrower head gap to play back the higher carrier frequency at 5.6 MHz. Later, some models would feature further improvement, in the form of Beta-Is, a high band version of the Beta-I recording mode. There were some incompatibilities between the older Beta decks and SuperBeta, but most could play back a high band tape without major problems. SuperBeta decks had a switch to disable the SuperBeta mode for compatibility purposes. (SuperBeta was only marginally supported outside of Sony, as many licensees had already discontinued their Betamax line.)
In 1988, Sony would again push the envelope with ED Beta, or "Extended Definition" Betamax, capable of up to 500 lines of resolution, that equaled DVD quality (480 typical). In order to store the ~6.5 MHz-wide luma signal, with the peak frequency at 9.3 MHz, Sony used a metal formulation tape borrowed from the Betacam SP format (branded "ED-Metal") and incorporated some improvements to the transport to reduce mechanically induced aberrations in the picture. Beta ED also featured a luminance carrier deviation of 2.5 MHz, as opposed to the 1.2 MHz used in SuperBeta, improving contrast with reduced luminance noise.
Sony introduced two ED decks and a camcorder in the late 1980s. The top end EDV-9500 (EDV-9300 in Canada) deck was a very capable editing deck, rivaling much more expensive U-Matic set-ups for its accuracy and features, but did not have commercial success due to lack of timecode and other pro features. Sony did market Beta ED to "semiprofessional" users, or "prosumers". One complaint about the EDC-55 ED CAM was that it needed a lot of light (at least 25 lux), due to the use of two CCDs instead of the typical single-CCD imaging device. The Beta ED lineup only recorded in BII/BIII modes, with the ability to play back BI/BIs.
Despite the sharp decline in sales of Betamax recorders in the late 1980s and subsequent halt in production of new recorders by Sony in 2002, both Betamax and SuperBetamax are still being used by a small number of people. New cassettes are still available for purchase at online shops and used recorders are often found at flea markets, thrift stores or on Internet auction sites. Early format BetaCam cassettes—which are physically based on the Betamax cassette—continue to be available for use in the professional media.
Comparison with other video formats
Size comparison between a Betamax cassette (top) and a VHS cassette (bottom).
Below is a list of modern, digital-style resolutions (and traditional analog "TV lines per picture height" measurements) for various media. The list only includes popular formats. Note that listed resolution applies to luminance only, with chroma resolution usually halved in each dimension for digital formats, and significantly lower for analog formats.
Luminance Display resolution based on the quality of a standard. Equivalent pixel resolutions calculated from analog line resolution numbers. NTSC Systems,
- 330×480 (250 lines per picture height): Umatic, Betamax, VHS, Video8
- 400×480 (300 lines per picture height): Super Betamax, Betacam (professional)
- 440×480 (330 lines per picture height): NTSC Analog Broadcast
- 560×480 (420 lines per picture height): LaserDisc, Super VHS, Hi8
- 670×480 (500 lines per picture height): Extended Definition Betamax
- 330×576 (250 lines per picture height): Umatic, Betamax, VHS, Video8
- 400×576 (300 lines per picture height): Super Betamax, Betacam (professional)
- 520×576 (390 lines per picture height): PAL B,G,H Analog Broadcast
- 560×576 (420 lines per picture height): LaserDisc, Super VHS, Hi8
- 570×576 (430 lines per picture height): PAL I Analog Broadcast
- 620×576 (470 lines per picture height): PAL D/K Analog Broadcast
- 670×576 (500 lines per picture height): Extended Definition Betamax
Digital formats Luminance Display resolution based on the quality of a standard. Equivalent analog line resolution numbers calculated from pixel resolutions. The somewhat unintuitive analog resolution loss for 16:9 DVD compared to 4:3 DVD comes from that analog resolution unit is "lines per picture height". When picture height is kept the same, the same 720 pixels are spread to a wider area in 16:9, hence lower horizontal resolution per picture height.
- 352×240 (260 lines per picture height): Video CD, 4:3
- 480×480 (360 lines per picture height): SVCD, 4:3
- 720×480 (410 lines per picture height): Anamorphic NTSC Widescreen DVD, 16:9
- 720×360 (410 lines per non-black picture height): Letterbox NTSC Widescreen DVD, 4:3
- 720×480 (540 lines per picture height): 4:3 NTSC DVD, DV, miniDV, Digital8, 4:3
- 1280×720 (720 lines per picture height): AVCHD-lite (720p), 16:9
- 1440×1080 (810 lines per picture height): miniDV (high-def variant), 16:9
- 1920×1080 (1080 lines per picture height): (1080i/p) AVCHD, Blu-ray, HD DVD, 16:9