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Video High Density

February 11, 2024

Video High Density (VHD) is an analog video format which was marketed predominantly in Japan by JVC.

Video High Density
A VHD disc; pictured is a copy of the 1961 Italian film "Girl With a Suitcase"
Media typevideo playback media
Capacity60 minutes NTSC video per side
Read mechanismstylus
UsageHome video
Released1983

History edit

VHD was first demonstrated in 1978, and after numerous advertisements in 1981/1982 National Geographic magazines, it was eventually released in Japan on April 21, 1983. By this time, both LaserDisc and CED were already suffering from the onslaught of VHS and Betamax VCRs. Despite demonstrating the player at several Consumer Electronics Shows, JVC opted not to release VHD as a consumer product in North America.

In the UK Thorn EMI, which was the leading consumer provider of the VHS tape system, saw VHD as the next step in the market and committed to the system. In 1981 it invested in a factory to press discs (in Swindon) and a production unit to develop a catalogue of "interactive" titles—a unique step—to support a planned 1984 launch but canceled the investment in late 1983. VHD remained on the market in the UK primarily as an educational and training tool, usually linked to a computer, but attracted few customers.

It found its main niche as a karaoke system, and was also used in anime video games and interactive training systems. Commercial versions were available in the UK (and probably the US) for training, demonstration and fault diagnosis.

A stereoscopic system was also sold in Japan; these 3D VHD systems achieved the 3D effect using double-speed discs with alternate-eye images and LCS glasses to pass the correct view to each eye.

VHD became obsolete after 1987. Discs continued to be manufactured up until the early 1990s. The last new release on the format was in late 1990.

Technology edit

VHD discs are 25 centimetres (9.8 in) in diameter, and store up to 60 minutes of video per side.[1] As with CED, each disc is stored in a caddy: the user never handles the disc directly. The entire caddy is inserted into the player, and then withdrawn, leaving the disc inside where it will be loaded and start playing. At the end of the side the disc must be removed, turned over and re-inserted.

Like the RCA system, the signal is recorded on the discs as variations in capacitance, a conductive coating on the disc itself forming part of a resonant circuit. A diamond stylus reads the signal, though unlike CED there are no actual grooves—the stylus follows the tracks electronically, like a compact disc. This means less wear, though there is still physical contact (unlike LaserDisc) so some wear would still occur.

The discs contain two frames (four fields) per revolution, and play in CAV mode, which makes play simple, as all frames start at the same place on the disc, but having two frames per rotation means that true freeze frame is not possible — there would be some "jitter" on moving sequences (discs which were designed to be used a frame at a time - such as picture catalogues - doubled up the frames, to get true stills at the cost of reduced capacity).

The VHD system had advantages over both CED and LaserDisc. In active (CAV) mode (not available in CED) it had a greater capacity than LaserDisc. It also had the ability to carry 99 randomly accessible 'chapters' (more than LaserDisc) and had the same autostop capability. These two functions had to be programmed into the master tape from which the videodisc was made, along with the two-frame freeze frame function. This made videotape master editing a highly specialist operation requiring precise insertion of vertical interval codes into the video signal, and field accurate editing (most videotape editing required only frame accuracy).

VHD was always intended as a highly interactive format, and many non-linear 'trick-play' features were supported, directly by the players or via an optional VHDpc computer interface for the MSX and Sharp X1 computers.

Uses edit

Applications included interactive adventure games, and car engine diagnostic tools. Constructing an interactive disc required a lot of planning as well as the specialist video master editing. The costs entailed in discovering these complexities and solving the problems, as well as recognising that the video post-production technology of the time was being pushed to its limits probably contributed to the decision to withdraw the system.

Offshoots edit

There was also a digital audio-only variant, Audio High Density (AHD; not released/canceled).[citation needed]

References edit

  1. ^ VHD Disc World

External links edit

  • Total Rewind—The Virtual Museum of Vintage Video
  • VHD DiscWorld
  • The LaserDisc Database—LD/CED/VHD discs, profiling and marketplace

February 11, 2024
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This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article relies excessively on references to primary sources Please improve this article by adding secondary or tertiary sources Find sources Video High Density news newspapers books scholar JSTOR April 2010 Learn how and when to remove this template message This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Video High Density news newspapers books scholar JSTOR October 2011 Learn how and when to remove this template message This article s lead section may be too short to adequately summarize the key points Please consider expanding the lead to provide an accessible overview of all important aspects of the article July 2023 Learn how and when to remove this template message This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages You can help expand this article with text translated from the corresponding article in Japanese May 2021 Click show for important translation instructions View a machine translated version of the Japanese article Machine translation like DeepL or Google Translate is a useful starting point for translations but translators must revise errors as necessary and confirm that the translation is accurate rather than simply copy pasting machine translated text into the English Wikipedia Consider adding a topic to this template there are already 3 757 articles in the main category and specifying topic will aid in categorization Do not translate text that appears unreliable or low quality If possible verify the text with references provided in the foreign language article You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation A model attribution edit summary is Content in this edit is translated from the existing Japanese Wikipedia article at ja VHD see its history for attribution You should also add the template Translated ja VHD to the talk page For more guidance see Wikipedia Translation Learn how and when to remove this template message Video High Density VHD is an analog video format which was marketed predominantly in Japan by JVC Video High DensityA VHD disc pictured is a copy of the 1961 Italian film Girl With a Suitcase Media typevideo playback mediaCapacity60 minutes NTSC video per sideRead mechanismstylusUsageHome videoReleased1983 Contents 1 History 2 Technology 3 Uses 4 Offshoots 5 References 6 External linksHistory editVHD was first demonstrated in 1978 and after numerous advertisements in 1981 1982 National Geographic magazines it was eventually released in Japan on April 21 1983 By this time both LaserDisc and CED were already suffering from the onslaught of VHS and Betamax VCRs Despite demonstrating the player at several Consumer Electronics Shows JVC opted not to release VHD as a consumer product in North America In the UK Thorn EMI which was the leading consumer provider of the VHS tape system saw VHD as the next step in the market and committed to the system In 1981 it invested in a factory to press discs in Swindon and a production unit to develop a catalogue of interactive titles a unique step to support a planned 1984 launch but canceled the investment in late 1983 VHD remained on the market in the UK primarily as an educational and training tool usually linked to a computer but attracted few customers It found its main niche as a karaoke system and was also used in anime video games and interactive training systems Commercial versions were available in the UK and probably the US for training demonstration and fault diagnosis A stereoscopic system was also sold in Japan these 3D VHD systems achieved the 3D effect using double speed discs with alternate eye images and LCS glasses to pass the correct view to each eye VHD became obsolete after 1987 Discs continued to be manufactured up until the early 1990s The last new release on the format was in late 1990 Technology editVHD discs are 25 centimetres 9 8 in in diameter and store up to 60 minutes of video per side 1 As with CED each disc is stored in a caddy the user never handles the disc directly The entire caddy is inserted into the player and then withdrawn leaving the disc inside where it will be loaded and start playing At the end of the side the disc must be removed turned over and re inserted Like the RCA system the signal is recorded on the discs as variations in capacitance a conductive coating on the disc itself forming part of a resonant circuit A diamond stylus reads the signal though unlike CED there are no actual grooves the stylus follows the tracks electronically like a compact disc This means less wear though there is still physical contact unlike LaserDisc so some wear would still occur The discs contain two frames four fields per revolution and play in CAV mode which makes play simple as all frames start at the same place on the disc but having two frames per rotation means that true freeze frame is not possible there would be some jitter on moving sequences discs which were designed to be used a frame at a time such as picture catalogues doubled up the frames to get true stills at the cost of reduced capacity The VHD system had advantages over both CED and LaserDisc In active CAV mode not available in CED it had a greater capacity than LaserDisc It also had the ability to carry 99 randomly accessible chapters more than LaserDisc and had the same autostop capability These two functions had to be programmed into the master tape from which the videodisc was made along with the two frame freeze frame function This made videotape master editing a highly specialist operation requiring precise insertion of vertical interval codes into the video signal and field accurate editing most videotape editing required only frame accuracy VHD was always intended as a highly interactive format and many non linear trick play features were supported directly by the players or via an optional VHDpc computer interface for the MSX and Sharp X1 computers Uses editApplications included interactive adventure games and car engine diagnostic tools Constructing an interactive disc required a lot of planning as well as the specialist video master editing The costs entailed in discovering these complexities and solving the problems as well as recognising that the video post production technology of the time was being pushed to its limits probably contributed to the decision to withdraw the system Offshoots editThere was also a digital audio only variant Audio High Density AHD not released canceled citation needed References edit VHD Disc WorldExternal links editTotal Rewind The Virtual Museum of Vintage Video VHD DiscWorld The LaserDisc Database LD CED VHD discs profiling and marketplace Retrieved from https en wikipedia org w index php title Video High Density amp oldid 1167949953, wikipedia, wiki, book, books, library,

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