Media type | Magnetic Tape |
---|---|
Encoding | NTSC, PAL |
Read mechanism | Helical scan |
Write mechanism | Helical scan |
Developed by | Ampex and Sony |
Usage | Television production |
Released | 1976 |
1-inch Type C Helical Scan or SMPTE C is a professional reel-to-reel analog recording helical scan videotape format co-developed and introduced by Ampex and Sony in 1976. It became the replacement in the professional video and broadcast television industries for the then-incumbent 2-inch quadruplex videotape (2-inch Quad for short) open-reel format. Additionally, it replaced the unsuccessful type A format, also developed by Ampex, and primarily in mainland Europe, it supplemented the type B format, developed by the Fernseh division of Bosch.
Compared to Quad, Type C had a smaller size, comparative ease of operation, and slightly higher video quality. 1-inch Type C is capable of "trick-play" functions such as still, shuttle, and variable-speed playback, including slow motion. 2-inch quadruplex videotape machines lacked these capabilities, due to the segmented manner in which it recorded video tracks onto the magnetic tape. 1-inch Type C VTRs required much less maintenance and used less power and space than did 2-inch machines.
1-inch Type C records composite video at a very high video quality that was superior to contemporary color-under formats such as U-matic, and of comparable quality to analog component video formats like Betacam and MII. Both analog component formats were notoriously fussy and trouble-prone, so in practice Type C gave a stable, more reliable picture than the broadcast quality analog cassette-based videotape formats. Because television was broadcast as a composite signal, there was no real downside to Type C in television broadcasting and distribution. It had approximately 300 lines of resolution, [1] and a bandwidth of 5 MHz, with recording being done with the heads moving across the tape at (a writing speed of) 1,008 inches per second, [2] or 25.59 meters per second for NTSC signals, and 21.39 meters per second for PAL signals. As for linear tape speeds, type C VTRs could run at 24.4 centimeters per second for NTSC, and 23.98 centimeters per second for PAL. [3]
Type C VTRs can record a single complete video field in a single revolution of the drum, using a single video head, which made the format useful in computer animation and allowed for stills without frame stores or buffers. The tape is almost completely wrapped around the drum of the VTR in what is known as an omega wrap. Because the omega wrap only wraps the tape 346° around the drum, the vertical blanking interval of the video signal is lost, a problem solved by using a "1 1/2 head" system in which a secondary head scans or reads a narrow strip with the vertical blanking interval when the video head is not reading a video track on the tape. [4] [5]
Sometimes in interlaced video a field is called a frame which can lead to confusion. [6] The NTSC and PAL formats recorded by Type C VTRs are interlaced video formats and thus there is a vertical blanking interval after every field of video. [7] [8]
The format is almost immune to dropouts. [9] PAL Type C VTRs may have higher writing speeds to achieve higher bandwidth given PAL's 5-6 MHz bandwidth versus NTSC's 4.2 MHz. In practice, type C VTRs may have a bandwidth of 4.2 MHz for NTSC, and 5 MHz for PAL. [3] Type C VTRs may have flying video erase heads mounted on the drum, allowing for individual frames to be erased. [10] Some Type C VTRs could support reels with enough tape for 126 minutes of playback with NTSC, and 128 minutes with PAL, with 11.75 inch reels. [3]
1-inch tape gained numerous uses in television production including outside broadcasts where it was used for instant replays and creating programme titles. 1-inch machines were considerably smaller and more reliable than preceding two-inch versions and were seen by operators as a major technological breakthrough. Due to this smaller size, it was possible for OB crews[ clarification needed ] to transport and use multiple machines, allowing for much more complex editing to be done on site for use within the programme. [11] The quality and reliability of 1-inch Type C made it a mainstay in television and video production in television studios for almost 20 years, before being supplanted by more reliable digital videocassette formats like Digital Betacam, DVCAM, and DVCPRO. 1-inch Type C was also widely used for the mastering of early LaserDisc titles. It was replaced in that role by the digital D-2 videocassette format in the late 1980s.
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In 1983, RCA turned to Ampex for supply of Helical VTRs.
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Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic tape can with relative ease record and play back audio, visual, and binary computer data.
Videotape is magnetic tape used for storing video and usually sound in addition. Information stored can be in the form of either an analog or digital signal. Videotape is used in both video tape recorders (VTRs) and, more commonly, videocassette recorders (VCRs) and camcorders. Videotapes have also been used for storing scientific or medical data, such as the data produced by an electrocardiogram.
S-VHS (スーパー・ヴィエイチエス), the common initialism for Super VHS, is an improved version of the VHS standard for consumer-level video recording. Victor Company of Japan introduced S-VHS in Japan in April 1987, with their JVC-branded HR-S7000 VCR, and in certain overseas markets soon afterward. By the end of 1987, the first S-VHS VCR models from other competitors included the Hitachi VT-2700A, Mitsubishi HS-423UR, Panasonic PV-S4764, RCA VPT-695HF, and Toshiba SV-950. It has been standardized as IEC 60774-3 and IEC 60774-4.
Ampex Data Systems Corporation is an American electronics company founded in 1944 by Alexander M. Poniatoff as a spin-off of Dalmo-Victor. The name AMPEX is an acronym, created by its founder, which stands for Alexander M. Poniatoff Excellence. Ampex operates as Ampex Data Systems Corporation, a subsidiary of Delta Information Systems, and consists of two business units. The Silicon Valley unit, known internally as Ampex Data Systems (ADS), manufactures digital data storage systems capable of functioning in harsh environments. The Colorado Springs, Colorado, unit, referred to as Ampex Intelligent Systems (AIS), serves as a laboratory and hub for the company's line of industrial control systems, cyber security products and services and its artificial intelligence/machine learning technology.
Helical scan is a method of recording high-frequency signals on magnetic tape, used in open-reel video tape recorders, video cassette recorders, digital audio tape recorders, and some computer tape drives.
D-1 or 4:2:2 Component Digital is an SMPTE digital recording video standard, introduced in 1986 through efforts by SMPTE engineering committees. It started as a Sony and Bosch – BTS product and was the first major professional digital video format. SMPTE standardized the format within ITU-R 601, also known as Rec. 601, which was derived from SMPTE 125M and EBU 3246-E standards.
Betacam is a family of half-inch professional videocassette products developed by Sony in 1982. In colloquial use, Betacam singly is often used to refer to a Betacam camcorder, a Betacam tape, a Betacam video recorder or the format itself.
A video tape recorder (VTR) is a tape recorder designed to record and playback video and audio material from magnetic tape. The early VTRs were open-reel devices that record on individual reels of 2-inch-wide (5.08 cm) tape. They were used in television studios, serving as a replacement for motion picture film stock and making recording for television applications cheaper and quicker. Beginning in 1963, videotape machines made instant replay during televised sporting events possible. Improved formats, in which the tape was contained inside a videocassette, were introduced around 1969; the machines which play them are called videocassette recorders.
U-matic or 3⁄4-inch Type E Helical Scan or SMPTE E is an analogue recording videocassette format first shown by Sony in prototype in October 1969, and introduced to the market in September 1971. It was among the first video formats to contain the videotape inside a cassette, as opposed to the various reel-to-reel or open-reel formats of the time. The videotape is 3⁄4 in (19 mm) wide, so the format is often known as "three-quarter-inch" or simply "three-quarter", compared to open reel videotape formats in use, such as 1 in (25 mm) type C videotape and 2 in (51 mm) quadruplex videotape.
D-2 is a professional digital videocassette format created by Ampex and introduced in 1988 at the NAB Show as a composite video alternative to the component video D-1 format. It garnered Ampex a technical Emmy in 1989. Like D-1, D-2 stores uncompressed digital video on a tape cassette; however, it stores a composite video signal, rather than component video as with D-1. While component video is superior for advanced editing, especially when chroma key effects are used, composite video was more compatible with most analog facilities existing at the time.
1-inch Type A Helical Scan or SMPTE A is a reel-to-reel helical scan analog recording videotape format developed by Ampex in 1965, that was one of the first standardized reel-to-reel magnetic tape formats in the 1–inch (25 mm) width; most others of that size at that time were proprietary. It was capable of 350 lines.
1-inch Type B Helical Scan or SMPTE B is a reel-to-reel analog recording video tape format developed by the Bosch Fernseh division of Bosch in Germany in 1976. The magnetic tape format became the broadcasting standard in continental Europe, but adoption was limited in the United States and United Kingdom, where the Type C videotape format met with greater success.
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Electronovision was a process used by producer and entrepreneur H. William "Bill" Sargent, Jr. to produce a handful of motion pictures, theatrical plays, and specials in the 1960s and early 1970s using a high-resolution videotape process for production, later transferred to film via kinescope for theatrical release.
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