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  FAQ's:
What is a Laservision Standard Videodisc?
 

 

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WHAT IS A LASERVISION STANDARD VIDEODISC?

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HOW ARE IMAGES AND SOUNDS VIEWED ON A VIDEODISC?

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IS A VIDEODISC SIGNAL DIGITAL?

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WHY IS THE SLICE OF LIFE OR SLICE OF BRAIN ON VIDEODISC AND NOT ON CD-ROM, DVD-ROM, OR DVD-VIDEODISC?

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IS IT "DISC" OR "DISK" ?

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WHO MAKES VIDEODISC PLAYERS?

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HOW CAN I BUY A VIDEODISC PLAYER TODAY?

 

 

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WHAT IS A LASERVISION STANDARD VIDEODISC?

A videodisc is an analog video playback medium. It was first introduced in the early 1980s, and in its present form is known as the laservision videodisc and is a 12-inch plastic platter.

There are two modes in which a videodisc can be made. The most familiar one is called "Extended Play" or CLV (Constant Linear Velocity). This mode is the one most commonly used for laserdisc movies. It has 60 minutes of play per side, does not allow "pause" or "still frame" function, and can randomly access chunks of motion sequences known as "chapters."

The other mode is called CAV (Constant Angular Velocity) and is the one used most often for interactive training. It has 30 minutes of motion play per side. The biggest difference is that the 30 minutes is the equivalent of 54,000 still frames, each one randomly accessible. The CAV mode is used for the SLICE OF LIFE VII and SLICE OF BRAIN I videodiscs because it allows us to encode tens-of-thousands of images onto one side of a videodisc. Each frame is addressable and can be "paused" indefinitely during playback.

 

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HOW ARE IMAGES AND SOUNDS VIEWED ON A VIDEODISC?

The playback of stills, motion sequences and sound from a videodisc is similar to that of a standard home VCR. The output signal is fed to a television set or monitor. In most interactive training scenarios, the videodisc requires what is often called a "two screen solution" in which the computer-based materials are displayed on a computer monitor and the videodisc images are seen on a TV set. Many users channel the output of the videodisc signal through an analog-to-digital image capture card, thus allowing the disc images to be viewed through the computer monitor ("single-screen solution").

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IS A VIDEODISC SIGNAL DIGITAL?

No. The final output of a laservision videodisc is an analog NTSC standard television signal (at least in North America...other television standards, such as PAL and SECAM exist throughout the world). The SLICE OF LIFE and SLICE OF BRAIN videodiscs use the NTSC standard and thus are viewable through regular television sets. Each frame of a CAV formatted videodisc is like a still-frame from a video. These frames are not stored as individual files, such as a jpeg, gif, bmp, or pict file formats common in the computer world. They can only be recalled for playback by their individual videodisc frame numbers.

Although the content of a videodisc is encoded in pits and landings and read by a laser, in the final analysis, the laservision videodisc is like a glorified, high quality, LP record, except it plays video in addition to sounds.

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WHY IS THE SLICE OF LIFE OR SLICE OF BRAIN ON VIDEODISC AND NOT ON CD-ROM, DVD-ROM, OR DVD-VIDEODISC?

Do not confuse the SLICE OF LIFE or SLICE OF BRAIN laservision videodisc with CD-ROM or DVD-ROM and DVD-Videodisc technologies. SOL VII and SOB I are traditional 12-inch videodiscs whose images can be seen by connecting the output of the laserdisc player to a television monitor. It offers instant random access to any of the 54,000 frames.

These frames are not stored as individual picture files as you would find with a CD-ROM or DVD-ROM. The DVD videodiscs use MPEG2 compression to encode movies onto the small CD-Audio sized discs. MPEG2 is designed for motion compression, not stills.

The advantages of the laserdisc medium are its stability, quality, extremely fast image retrieval, and density of information on a single disc. Keep in mind that in 1986 when this project began, CD-ROMs were yet to be invented. Today, it would require about 10 CD-ROMs to hold all 54,000 laserdisc images in a compressed JPEG file format. For more detailed information about digital versions of Slice of Life, refer to the FAQ IS SLICE OF LIFE GOING DIGITAL?

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IS IT "DISC" OR "DISK" ?

Ten years ago, the industry finally decided to end the confusion and decreed that the words laserdisc and videodisc would be spelled with a final "c" and not with a "k" as is used in the computer industry for such words as "floppy disk." Impress your colleagues and insist on the "c" spelling. The DVD-Videodiscs inherited the same spelling with a "c."

 

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WHO MAKES VIDEODISC PLAYERS?

The manufacturers of videodisc players were more numerous in the past. Recently Sony stopped making them even though their Model 2000 was a work horse and continues to keep working even after a decade of use in many libraries. In North America, Pioneer continues to sell industrial grade players, many of them now being "combo" units that play videodiscs, DVD-Videodiscs, and CD-Audio discs. Industrial players often have RS-232 serial control connectors on the back (see the FAQs on HOW DO I CONTROL THE PLAYBACK OF A LASERDISC?) Sales are still made, particularly in the interactive training and educational markets.

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HOW CAN I BUY A VIDEODISC PLAYER/REMOTE CONTROLLER TODAY?

You won't find a laservision videodisc player in your neighborhood Best Buy, Fry's, or electronics store. The technology has been replaced by DVD-Videodisc players (at least for movies). Some fans of Slice of Life report that eBay has been a good source for used or like-new videodisc players. Pioneer still sells industrial grade players, usually through Prosumer AV dealers. Consult the Pioneer Electronics website for more information about videodisc players. In Salt Lake City, vendors still offering videodisc players or able to order professional-grade players include:

Inkley's Audio Visual
2150 South State
Salt Lake City, Utah 84115 USA
801-486-5985

RIA, Inc.
50 East Malvern Ave
Salt Lake City, Utah 84154 USA
801-486-8822

If you need to find a remote hand-controller, we've found various models on this web-based retailer: http://www.replacementremotes.com

 

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