Videotape

Commercial videotape use started in 1956 in the form of 2-inch quad tape, used in Australia from 1958 to 1985. In a little over 40 years, more than 50 formats have been introduced world wide, each relying on the same fundamental process of recording image and sound data onto magnetic tape.

Formats

U-Matic

U-Matic (in common lingo ’3/4’ after the tape width in inches) is a format developed by Sony. It has three different versions: LowBand (LB), HighBand (HB) and Special Performance (SP), which differ by the subcarrier frequencies used for luminance and chrominance recording. U-Matic LB has been around from the early 1970s and is one of the oldest cassette video formats. HB has increased chroma subcarrier frequency, which improves colour resolution. In the SP variant, both chroma and luma subcarrier frequencies have been increased. U-Matic SP is still occasionally used as a production format for those not wealthy enough to use Beta SP or similar.

Although U-Matic does not appear much better than Super VHS on paper, the higher colour resolution and much better signal-to-noise ratio make the picture subjectively far more enjoyable. The U-Matic tape transport is also much faster in changing modes, which makes editing less frustrating. LB and HB U-Matic tapes were often used for archiving because of the relatively low tape costs and low recording density, which makes the tapes robust against aging.

In the early 1980s Sony introduced the semi-backward-compatible high band or BVU (Broadcast Video U-Matic) format, and the ‘original’ U-Matic format became known as low-band. This high-band format had an improved colour recording system and lower noise levels. The introduction of ENG (electronic news gathering) using the BVU platform for news and production brought instant results, unlike the film processes used to date. The expense and time limitations saw the end of using 16mm film for this everyday purpose.

1” SMPTE Type C Format

These machines use 1” tape in open reels. The main advantages are very fast transports and low recording density, which makes the format rather immune to drop-outs. Tape costs are high. The units can record single frames, which made them popular in early computer animation. Some units with vacuum capstans could operate from stop to nominal speed within one video field. The tape makes almost a full circle around the picture drum, and a single head is able to record and playback the entire video signal (short of a few lines right after vertical sync). Most other video formats have at least two picture heads, which alternate between fields. This format is now becoming obsolete. Note that in C format, the entire composite video signal is recorded and played back as is, without splitting it to Y/C, like most composite recorders do, or limiting the bandwidth in any way. The main manufacturers include Sony, Ampex and BTS.

1” SMPTE Type B Format

Similar to C format, but uses segmented helical scan. The diameter of the picture drum is small, and a single video field is recorded in six separate tracks. B format does not allow for many special modes – play, FF and REW are just about it. Manufactured by Bosch.

Betacam SP

Developed by Sony, perhaps the most popular format for both field acquisition and post production today. Betacam uses cassettes and transports similar to the old Betamax home video format, but the similarities end there. Tape speed is six times higher, and luminance and chrominance are recorded on two separate tracks. The two colour difference signals are compressed in time by two and recorded sequentially on a single track.

Digital Betacam

Digital successor to the venerable Betacam SP format. Introduced by Sony in 1993, uses physically similar half-inch cassettes. Camcorders with 40-minute capacity are available, making Digital Betacam the first component video digital ENG (electronic news gathering) format. Digital Betacam units play back, but do not record analogue Beta SP tapes.

DV/DVCam/DVCPRO

DV (formerly DVC) is a format being backed by manufacturers such as Sony, Philips, Thomson, Hitachi, Matsushita (Panasonic) and others. It was the first digital recording format in the reach of consumer markets. As a curiosity, the consumer version (DV) sports one of the densest recording techniques based on magnetic tape media – more than 0.4 megabits per square millimeter. DVCPRO is a professional variant of the DV by Panasonic. The only major difference is doubled tape speed, which is needed for better drop-out tolerance and general recording robustness. It is also capable of 4x normal speed playback. DVCAM on the other hand is Sony’s variation of the theme, sitting somewhere between DV and DVCPRO. Tape speed and track width have been increased, but not as much as for DVCPRO. Furthermore, it uses the same metal evaporated tape as DV, while DVCPRO uses metal particle tape.