LV-ROM (''LaserVision Read-Only Memory'') and LD-ROM (''LaserDisc Read-Only Memory'') are similar but incompatible

optical disc An optical disc is a flat, usuallyNon-circular optical discs exist for fashion purposes; see shaped compact disc. disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid o ...

formats that combine analog

LaserDisc LaserDisc (LD) is a home video format and the first commercial optical disc storage medium. It was developed by Philips, Pioneer Corporation, Pioneer, and the movie studio MCA Inc., MCA. The format was initially marketed in the United State ...

video with digitally encoded computer data. Both were developed to support interactive

multimedia Multimedia is a form of communication that uses a combination of different content forms, such as Text (literary theory), writing, Sound, audio, images, animations, or video, into a single presentation. T ...

by integrating

analog video Video is an Electronics, electronic medium for the recording, copying, playback, broadcasting, and display of moving picture, moving image, visual Media (communication), media. Video was first developed for mechanical television systems, whi ...

playback with computer-controlled navigation and overlays. While LV-ROM was developed in the 1980s primarily for educational and documentary purposes, LD-ROM was introduced in the 1990s to support video game software for consumer entertainment systems.

LV-ROM

The LV-ROM format was developed by

Philips Koninklijke Philips N.V. (), simply branded Philips, is a Dutch multinational health technology company that was founded in Eindhoven in 1891. Since 1997, its world headquarters have been situated in Amsterdam, though the Benelux headquarter ...

in the early 1980s. Similar to standard-play LaserDiscs, LV-ROM used constant angular velocity (CAV) playback, with analog video encoded using

pulse-width modulation Pulse-width modulation (PWM), also known as pulse-duration modulation (PDM) or pulse-length modulation (PLM), is any method of representing a signal as a rectangular wave with a varying duty cycle (and for some methods also a varying peri ...

. However, instead of audio, digital data was stored using the

Advanced Disc Filing System The Advanced Disc Filing System (ADFS) is a computing file system unique to the Acorn computer range and RISC OS-based successors. Initially based on the rare Acorn Winchester Filing System, it was renamed to the Advanced Disc Filing System when ...

developed by

Acorn Computers Acorn Computers Ltd. was a British computer company established in Cambridge, England in 1978 by Hermann Hauser, Christopher Curry (businessman), Chris Curry and Andy Hopper. The company produced a number of computers during the 1980s with asso ...

. Configured this way, each side of an LV-ROM disc could store up to 324 megabytes of digital data and 54,000 frames of either still images or analog video, equivalent to about 36 minutes at 25 frames per second. Where needed, the digital data could be substituted with analog audio. The most prominent use of the hybrid video/data LV-ROM format was in the BBC Domesday Project, a major multimedia initiative undertaken between 1984 and 1986 that compiled video interviews, statistical data, images, and maps to create an interactive record of life in the United Kingdom. Discs were accessed using a specially modified BBC Master computer (built by Acorn Computers) connected via a

SCSI Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices, best known for its use with storage devices such as hard disk drives. SCSI was introduced ...

interface board to a Philips VP415 LaserDisc player, which was developed specifically for the project. This made the Domesday system one of the first non-professional computing platforms to incorporate the emerging SCSI-1 parallel bus standard. Together, these components formed the BBC Master AIV (Acorn Interactive Video) system. A

time base corrector Time base correction (TBC) is a technique to reduce or eliminate errors caused by mechanical instability present in analog recordings on mechanical media. Without time base correction, a signal from a videotape recorder (VTR) or videocassette re ...

inside the player was connected to a reference signal generated by the computer (

genlock Genlock (generator locking) is a common technique where the video output of one source (or a specific reference signal from a signal generator) is used to synchronize other picture sources together. The aim in video applications is to ensure the ...

), allowing the system to overlay computer graphics in real time with the analog video output. Users interacted with the system using a

trackball A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down ball mouse (computing), mouse with an exposed protruding ball. Users roll the ball t ...

controller. Following the release of the original Domesday discs, the BBC produced several additional AIV titles for the educational market. Other organizations contributed to the AIV ecosystem as well.

Virgin Publishing Virgin Books is a British book publisher 90% owned by the publishing group Random House, and 10% owned by Virgin Group, the company originally set up by Richard Branson as a record company. History Virgin established its book publishing arm ...

released ''North Polar Expedition'', which combined video on a LaserDisc with software on a floppy disk.

Apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...

also developed its own LaserDisc-based educational project, the ''Apple Visual Almanac'', which was released in 1989.

LD-ROM

The LD-ROM format was developed by Pioneer and introduced in 1993 for use with the

LaserActive The is a hybrid LaserDisc player and home video game console released by Pioneer Corporation in 1993. Marketed as a high-end, modular entertainment system, it was designed to combine movies, music, and video games into a single unit. Out of the ...

, a hybrid LaserDisc player,

video game console A video game console is an electronic device that Input/output, outputs a video signal or image to display a video game that can typically be played with a game controller. These may be home video game console, home consoles, which are generally ...

, and

CD player A CD player is an electronic device that plays audio compact discs, which are a digital audio, digital optical disc data storage format. CD players were first sold to consumers in 1982. CDs typically contain recordings of audio material such a ...

. Unlike LV-ROM, which used constant angular velocity for frame-accurate video playback, LD-ROM employed constant linear velocity, like had been done with LaserDisc extended play. LD-ROM discs offered storage capacity reaching up to 540 MB of digital data per side on a typical disc, the same as an early

CD-ROM A CD-ROM (, compact disc read-only memory) is a type of read-only memory consisting of a pre-pressed optical compact disc that contains computer data storage, data computers can read, but not write or erase. Some CDs, called enhanced CDs, hold b ...

, in addition to 60 minutes of analog video and audio storage, which could be used for

cutscene A cutscene or event scene (sometimes in-game cinematic or in-game movie) is a sequence in a video game that is not interactive, interrupting the gameplay. Such scenes are used to show conversations between characters, set the mood, reward the ...

s in

full-motion video Full-motion video (FMV) is a video game narration technique that relies upon pre-recorded video files (rather than sprites, vectors, or 3D models) to display action in the game. While many games feature FMVs as a way to present information duri ...

. A smaller disc was also available, offering a reduced capacity. The format used a different file system from LV-ROM, and analog video/audio quality was affected by the CLV encoding approach. The LaserActive system supported video games on the LD-ROM disc, if the system was equipped with the optional expansion modules (PACs) that enabled compatibility with

Sega Genesis The Sega Genesis, known as the outside North America, is a 16-bit Fourth generation of video game consoles, fourth generation home video game console developed and sold by Sega. It was Sega's third console and the successor to the Master Sys ...

and

TurboGrafx-16 The TurboGrafx-16, known in Japan as the , is a home video game console developed by Hudson Soft and manufactured by NEC. It was released in Japan in 1987 and in North America in 1989. The first console of the fourth generation of video game con ...

game media. Variants of LD-ROM include: * MEGA LD – Used for software compatible with the Mega-CD/Sega CD platform. * LD-ROM² – Used for software compatible with the

PC Engine CD-ROM² The TurboGrafx-16, known in Japan as the , is a home video game console developed by Hudson Soft and manufactured by NEC. It was released in Japan in 1987 and in North America in 1989. The first console of the fourth generation, it launched in ...

platform. * LD-G – Discs designed for

karaoke is a type of interactive entertainment system usually offered in nightclubs and bars, where people sing along to pre-recorded accompaniment using a microphone. Its musical content is an instrumental rendition of a well-known popular song. I ...

content, similar to CD+G.

LV-ROM

LD-ROM

References

See also