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Betacam SP

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Betacam SP Logo
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Betacam SP Logo

Designed by Sony, the Betacam SP format has become the defacto broadcast video format world-wide. The "SP" stands for "Superior Performance", which was achieved by using a metal-formulated tape instead of oxide. Horizontal resolution was increased to around 360 lines. Tape sizes were the same as Betacam.

The Betacam SP format was designed for professional use and so advanced features such as Time Code and full editing functionality were built into the system from the start.


Contents

Betacam SP format history

Sony BVW-75 Videocassette Recorder
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Sony BVW-75 Videocassette Recorder

The successor to Sony's Betacam, Betacam SP was launched in 1986 and went on to become the most successful general-purpose professional video format of the 20th Century. Betacam SP was adopted as the standard format for field work such as ENG (electronic news gathering), but was also good enough to be used for edit mastering. Every respectable studio had Betacam SP capabilities.

The original series of Betacam SP VTRs is the BVW series of machines. In 1993 Sony released the UVW series to be followed later by the PVW series.

The UVW were the first series of budget machines. Heralded as 'Betacam for the masses' the launch of the UVW range brought the Betacam SP format within reach of many who until then had been unable to afford the high cost of the BVW series machines. The UVW machines lack many of the advanced features of the BVW series, such as AFM audio tracks, Dynamic tracking and VITC (Virtical Interval Time Code). The PVW series is intended to fill this gap and provide many of these features at a very economic price.

Betacam SP description

Betacam SP head layout
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Betacam SP head layout

Betacam SP is a high quality format based apon the component video standard. In this system a video signal is represented by three signals. One Luminance and two Chrominance. These signals are referred to as Y, U and V and are no more than a special way of encoding the Red, Green and Blue signals that make up all colour images.

The major features of the Betacam SP format are:

  • Use of metal tape to raise the recording density and thereby greatly improve the recording and playback video quality.
  • The introduction of a large cassette to extend recording time.
  • The addition of FM audio recording to support four audio channels available for recording and playback.

Unlike, it's predecessors such as the U-matic format, the Betacam SP format records all three signals independently so that there is minimal signal loss during the record/playback process. It is able to do this by using a process known as Compressed Time Division Multiplex (CTDM).

The signal carrying the colour information, U and V, is time compressed and recorded on to one video track while the luminance, or Y, signal is recorded onto a second track. The use of two separate tracks eliminates the cross colour and cross luminance effects inherent in composite recording. Both tracks are recorded using high frequency FM (frequency modulated) carriers. This allows for high bandwidth for the Luminance and Chrominance signals.

Betacam SP technical specifications

Betacam SP recording tracks
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Betacam SP recording tracks
Betacam SP recording tracks (in details)
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Betacam SP recording tracks (in details)


Basic Betamax SP System Data
Tape Width 1/2 inch
Drum Diameter 74.487 mm
Speed of Head Disc 1500 rev/min
Video head to Tape Speed 5.832 m/s
Tape Speed (PAL) 1.873
Video Head Gap 0.4 microns
Audio Track Width 1.05mm
Audio Frequency Response 50Hz - 10kHz
Sync Track Width 0.6mm
Maximum Recording Time (PAL L-830) 215 mins
S/N Ratio Colour Greater than 40dB
S/N Ratio B/W Greater than 43dB
Horizontal Resolution 260 lines
Angle of Video Tracks 5 00' stationary; 5 58' moving
End Sensors Inductive

Betacam SP tape

Betacam SP tape wrap
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Betacam SP tape wrap

The Betacam SP format uses 1/2-inch tape which runs at the high speed of 101.5mms. To increase running times to beyond 90 minutes a large format tape cassette was introduced. All the studio machines are capable of accepting both size of cassette without a need for any adapter.

The Betacam SP VTR records video tracks where luminance (Y) is recorded on one track and color (R-Y/B-Y) is recorded on a separate track (see the figure below). The benefits of using a separate track for luminance and color recording is an image with increased color and luminance detail information. This also minimizes the cross-color and luminance effects inherent in the composite recording format. In order to fit the two color channels onto a single track, Compressed Time Division Multiplex (CTDM) system for color recording is employed, where the two color difference signals are first compressed in time by two and then recorded sequentially.

Betacam SP differs from the plain Betacam system in that it uses high grade Metal Oxide tape to achieve greater performance through increased carrier and deviation frequencies. Most Betacam SP machines support playback of Betacam format tapes.

Betacam SP 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.

A Betacam SP studio VTR records onto a 1/2 inch (12.65mm) Metal Particle tape and can record for up to 90 minutes onto a single large cassette and up to 30 minutes onto a small cassette.

Betacam SP devices

The original series of Betacam SP VTRs is the BVW series of machines. In 1993 Sony released the UVW series to be followed later by the PVW series.

Compatibility

The Betacam SP studio VTR maintains playback compatibility with tapes recorded in analog Betacam recorders.


See also

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