Laserdisc versus VHS

Laserdisc vs. VHS

LD had a number of advantages over VHS. It featured a far sharper picture with a horizontal resolution of 400 lines for NTSC and 440 lines for PAL discs, while VHS only offered 250 lines. It could handle analog and digital audio where VHS was analog only, and the NTSC discs could store multiple audio tracks. This allowed for extras like director's commentary tracks and other features to be added on to a film, creating "Special Edition" releases that would not have been possible with VHS. Disc access was random and chapter based, like the DVD format, meaning that one could jump to any point on a given disc very quickly (depending on the player and the disc, within a few seconds at the most). (Random access is a general advantage of disc formats.) By comparison, VHS would require tedious rewinding and fast-forwarding to get to specific points. Laserdiscs were cheaper than videocassettes to manufacture, because they lack the moving parts and plastic outer shell that are necessary for VHS tapes to work. (A standard VHS cassette has at least 14 parts including the actual tape. A Laserdisc has one part, with five or six layers.)

Moreover, because the discs are read optically instead of magnetically, no physical contact needs to be made between the player and the disc, except for the player's clamp that holds the disc at its center as it's spun and read. As a result, playback doesn't wear the information-bearing part of the discs, and properly-manufactured LDs will theoretically last beyond one's lifetime. By contrast, a VHS tape holds all of its picture and sound information on the tape in a magnetic coating which rubs directly against the player heads, causing progressive wear with each use. Also, the tape is thin and delicate, and it is easy for a player mechanism (especially on a cheap model) to mishandle the tape and damage it by creasing, frilling (stretching) the edges, or even break it.

The format's support for multiple audio tracks allowed for vast supplemental materials to be included on-disc and made it the first viable format for "Special Edition" releases; the 1984 Criterion Collection edition of Citizen Kane is generally credited as being the first "Special Edition" release to home video, and for setting the standard by which future SE discs were measured. In addition, the format's instant seeking capability made it possible for a new breed of laserdisc-based video arcade games, beginning with Dragon's Lair, to be born.

Unfortunately, the format was not without its disadvantages. The discs were 30cm (12 inches) across, heavy, cumbersome, easier to damage on handling than a VHS cassette, and recording-capable units were not sold to the general public due to pressure from the film industry. And despite their massive storage capacity, the space-consuming analog video signal LDs couldn't store much video; depending on whether it was a CLV or CAV disc, each side of a given disc was limited to holding either 30 (for CAV discs) or 60 minutes (for CLV discs) of data. After one side was finished playing, a disc would have to be flipped over in order to continue watching the film, and many films required two discs (usually two sides of disc 1 and one side of disc 2) to contain them completely. Many players, especially units built after the mid-1980s, could "flip" discs automatically by rotating the optical pickup to the other side of the disc, but except in high-end models with a pre-read buffer, this was accompanied by a pause in the movie during the side change. In addition, if the movie was longer than what could be stored on 2 sides of a single disc, manually swapping to a second disc would be necessary at some point during the film. To make matters worse, many early LDs were not manufactured properly; sometimes a substandard adhesive was used to sandwich together the two sides of the disc, causing it to delaminate slightly. This would allow air in, which would cause the metallic part of the discs to oxidize. This eventually destroyed the disc as the oxidized aluminum lost its reflective property, a process known as "laser rot" among LD enthusiasts. (Early CDs suffered similar problems, including a notorious batch of defective discs manufactured by Philips-DuPont Optical in Europe during the early 1990s.)

Currently, the LaserDisc movie that has the most reported laser rot is the film Eraser (1996), as noted by the contributors of LaserDisc Database.

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