Betacam
Betacam is a professional (broadcast) video format developed by Sony in 1982 . The cassette housing of the failed Betamax home system was adopted for the camcorders of this system . Betacam was further developed into Betacam SP (1986), Digital Betacam (1993), Betacam SX (1996), Betacam IMX and the cinema and HD format HDCAM .
Before the transition to memory cards and servers, Betacam and its formats, grouped under the umbrella term Sony half-inch , were by far the market leaders for the production of TV, HDTV and tape-based digital cinema.
Videotape
Betacam uses the tape and cassette format already used by Betamax , but it uses a different recording system and is not compatible with Betamax.
Technical details
Betacam records oxide tape ( remanence : 750 oersted ), the luminance signal and the color difference signals RY BY (Cr Cb) having separate pairs of heads on separate tracks in CTDM method (. Compressed-time-division multiplex V). The color difference signals are written one after the other on the same track at twice the speed, i.e. compressed in time. This leads to a very high color quality (which is in no way comparable with the visibly modest quality of analog consumer devices such as S-VHS ). The image resolution ( visual acuity ) of the luminance signal reaches 4 MHz (−4 db) and represents the limit of what was then feasible with oxide tapes. It is thus the first cassette-based recording method that achieved that of the 1-inch C and B formats Almost offers a detailed resolution and exceeds it in terms of color resolution and clarity, because component video is saved instead of a composite video signal . The maximum playing time of 36 minutes is sufficient for camcorders for which the system was originally developed.
The bandwidth of the color channel for recording the color difference signals is 1.5 MHz (−3 db). Two audio tracks with (can be switched off) Dolby C and one address track (for SMPTE time code ) are used, VITC time code is recorded in the blanking interval .
Occurrence
Betacam was and is mainly used in the professional field for ENG / EFP . Almost every TV station can at least play Betacam.
Variations
- Betacam SP was a further development - thanks to better tape material (pure iron particles) and a higher FM carrier, the luminance bandwidth ("resolution") could be expanded. With the backward compatible format, larger cassettes (up to 90/108 minutes playing time) and improved studio recorders were introduced.
- Digital Betacam is digital and uses simple image data compression (block-based DCT method).
- Betacam SX is a further development of Betacam SP for faster copying and transmission in digital form and enables longer playing times thanks to MPEG-2 image data compression. It is mostly used by TV news agencies and is cheaper than Digital Beta.
- HDCAM is the highest quality and most expensive sub-format. It is mainly used for cinema and HD productions.
