U-matic
U-matic or 3⁄4-inch Type E Helical Scan[1][2] or SMPTE E[3] 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.
Media type
September 1971
Lifespan: September 1971–June 2000
Technical Support 1971–2016
Unlike most other cassette-based tape formats, the supply and take-up reels in the cassette turn in opposite directions during playback, fast-forward, and rewind: one reel would run clockwise while the other would run counter-clockwise. A locking mechanism integral to each cassette case secures the tape hubs during transportation to keep the tape wound tightly on the hubs. Once the cassette is taken off the case, the hubs are free to spin. A spring-loaded tape cover door protects the tape from damage; when the cassette is inserted into the VCR, the door is released and is opened, enabling the VCR mechanism to spool the tape around the spinning video drum. Accidental recording is prevented by the absence of a red plastic button fitted to a hole on the bottom surface of the tape; removal of the button disabled recording.
Some of the standards that define the format, are:[4]
Development[edit]
As part of its development, in March 1970, Sony, Matsushita Electric Industrial Co. (Panasonic), Victor Co. of Japan (JVC), and five non-Japanese companies reached agreement on unified standards. The first U-matic VCRs were released by Sony in 1971.[5]
The first generation of U-matic VCRs are large devices, approximately 30 in (76 cm) wide, 24 in (61 cm) deep, and 12 in (30 cm) high, requiring special shelving, and had mechanical controls limited to Record, Play, Rewind, Fast-Forward, Stop and Pause (with muted video on early models). Later models sported improvements such as chassis sized for EIA 19-inch rack mounting, with sliding rack rails for compressed storage in broadcast environments, solenoid control mechanics, jog-shuttle knob, remote controls, Vertical Interval Time Code (VITC), longitudinal time code, internal cuts-only editing controls, "Slo-Mo" slow-motion playback, and Dolby audio noise reduction.
U-matic was named after the shape of the tape path when it was threaded around the helical-scan video head drum, which resembles the letter U.[6] Betamax uses a similar type of "B-load" as well. Recording time is limited to one hour. It initially had a resolution of 250 lines. Signals are recorded onto the tape using Frequency modulation (FM modulation).
U-matic saw two revisions to improve its image quality. The first was high-band or Hi-band, introduced for PAL countries, with the original revision becoming known as low-band or Lo-band. This was followed by SP (superior performance), for NTSC and PAL countries. Both revisions increased the FM carrier frequencies, increasing the available bandwidth on the tape, hence increasing image quality and the number of lines. SP also introduced chrome dioxide tape. Hi-band U-matic recordings will play in black and white in Lo-band U-matic machines.[7]
PAL U-matic hi-band increased the FM carrier frequency to 4.8-6.4 MHz, while U-matic SP increased it even further to 5.6-7.2 MHz, while increasing the color carrier frequency to 924 kHz.[8]
U-matic tape moves at 3.75 inches per second, and has a tape writing speed of 8.54 meters per second for PAL or 10.26 for NTSC. This means that the heads on the drums of U-matic VCRs move across the tape at one of those speeds. The drum has two heads, both of which are used for recording video. The drum spins at 1500 rpm for PAL or 1800 rpm for NTSC.[9] U-matic low-band when recording NTSC has a sync tip frequency of 3.8 MHz, a peak white frequency of 5.4 MHz, and a color carrier frequency of 688.373 kHz. NTSC U-matic SP has a peak white frequency of 7 MHz.
When recording PAL, U-matic Hi-band had a sync tip frequency of 4.8 MHz, a peak white frequency of 6.4 MHz, and a color carrier frequency of 983.803 kHz, while U-matic Hi-Band SP had a sync tip frequency of 5.6 MHz, and a peak white frequency of 7.2 MHz, retaining the color carrier frequency of regular Hi-band.[10]
Introduction[edit]
At the 1971 introduction of the first model of U-Matic VCR, the VO-1600, Sony originally intended it to be a videocassette format oriented at the consumer market, even including a VHF/UHF TV tuner built into the model for home television recording. This proved to be something of a failure, because of the high manufacturing cost and resulting retail price of the format's first VCRs.[11] But the cost was affordable enough for industrial and institutional customers, where the format was very successful for such applications as business communication and educational television. As a result, Sony shifted U-Matic's marketing to the industrial, professional, and educational sectors.
U-Matic saw even more success from the television broadcast industry in the mid-1970s, when a number of local TV stations and national TV networks used the format when its first portable model, the Sony VO-3800, was released in 1974. This model ushered in the era of ENG, or electronic news gathering, which eventually made obsolete the previous 16mm film cameras normally used for on-location television news gathering. Film required developing which took time, compared to the instantly available playback of videotape, making faster breaking news possible.
Problems[edit]
A recurring problem with the format was damage to the videotape caused by prolonged friction of the spinning video drum heads against a paused videocassette. The drum would rub oxide off the tape or the tape would wrinkle; when the damaged tape was played back, a horizontal line of distorted visual image would ascend in the frame, and audio would drop out. Manufacturers attempted to minimize this issue with schemes in which the tape would loosen around the spinning head or the head would stop spinning after resting in pause mode for a pre-determined period of time.[16]
The format video image also suffered from head-switching noise, a distortion of the image in which a section of video at the bottom of the video frame would be horizontally askew from the larger portion.
The format also had difficulties with reproducing the red color on the NTSC color standard, and red images would be noisier than other colors in the spectrum. For this reason, on-camera talent was discouraged from wearing red clothing that would call attention to technical shortcomings.
Copying video from one U-matic VCR to another compromised playback reliability, and levels of head-switching noise, chroma smearing, and chroma noise compounded with every generation. These issues motivated videotape editors and engineers to use work-arounds to minimise this degradation. A time-base corrector (TBC) could be used to regenerate the sync tip portion of the video signal sent to the "recording" VCR, improving playback reliability. The "dub" cable, more formally called "demodulated" (or "demod" for short), was a multi-conductor cable that circumvented a portion of the video circuitry, minimising amplification noise.[17]
Uses[edit]
For synchronisation to broadcast or post-production editing house genlock systems, U-Matic VCRs required a time base corrector (TBC). Some TBCs had a drop-out compensation (DOC) circuit which would hold lines of video in temporary digital memory to compensate for oxide drop-out or wrinkle flaws in the videotape, however the DOC circuits required several cables and expert calibration for use.
U-matic tapes were also used for easy transport of filmed scenes for dailies in the days before VHS, DVD, and portable hard drives. Several movies have surviving copies in this form. The first rough cut of Apocalypse Now, for example (the raw version of what became Apocalypse Now Redux), survived on three U-Matic cassettes.[18]
Audio quality was compromised due to the use of longitudinal audio tape heads in combination with slow tape speed. Sony eventually implemented Dolby noise reduction circuitry (using Dolby C) to improve audio fidelity.
The 2012 film No, set in 1980s Chile, used U-matic tape for filming.[19]