Editing LaserDisc (section)

== Comparison with other formats ==
{{For|a [[List of common resolutions|comparison of consumer video resolutions]]|List of common resolutions#Television and media}}

=== VHS ===
LaserDisc had several advantages over [[VHS]]. It featured a far sharper picture with a horizontal [[Image resolution|resolution]] of 425&nbsp;[[television lines]] (TVL) for NTSC and 440&nbsp;TVL for PAL discs, while VHS featured only 240&nbsp;TVL<ref name="Video interchange" /> with NTSC. [[Super VHS]], released in 1987, reduced the quality gap, having horizontal luma resolution comparable to LaserDisc. But horizontal chroma resolution of Super VHS remained as low as that of standard VHS, about 40&nbsp;TVL, while LaserDisc offered about 70&nbsp;TVL of chroma resolution.<ref>[https://cool.culturalheritage.org/jaic/articles/jaic40-03-003_4.html A case study in the examination, documentation and preservation of a video-based installation by Paul Messier], Journal of the American Institute for Conservation</ref>

LaserDisc could handle analog and digital audio where VHS was mostly analog only (VHS could have PCM audio in professional applications but it was uncommon), and the NTSC discs could store multiple audio tracks. This allowed for extras such as director's commentary tracks and other features to be added onto 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. By comparison, VHS would require tedious rewinding and fast-forwarding to get to specific points.

''Initially'', LaserDiscs were cheaper than videocassettes to manufacture, because they lacked the moving parts and plastic outer shell which were necessary for VHS tapes to work, and the duplication process was much simpler. A VHS cassette had at least 14 parts (including the actual tape) while LaserDisc had one part with five or six layers. A disc could be stamped out in a matter of seconds, whereas duplicating videotape required a complex bulk tape duplication mechanism and was a time-consuming process. By the end of the 1980s, average disc-pressing prices were over $5.00 per two-sided disc, due to the large amount of plastic material and the costly glass-mastering process needed to make the metal stamper mechanisms. Due to the larger volume of demand, videocassettes quickly became much cheaper to duplicate, costing as little as $1.00 by the beginning of the 1990s.

LaserDiscs potentially had a much longer lifespan than videocassettes. Because the discs were read optically instead of magnetically, no physical contact needed to be made between the player and the disc, except for the player's clamp that holds the disc at its center as it is spun and read. As a result, playback would not wear the information-bearing part of the discs, and properly manufactured LaserDiscs could theoretically last beyond a lifetime. By contrast, a VHS tape held all of its picture and sound information on the tape in a magnetic coating which was in contact with the spinning heads on the head drum, causing progressive wear with each use (though later in VHS's lifespan, engineering improvements allowed tapes to be made and played back without contact). The tape was also thin and delicate, and it was easy for a player mechanism, especially on a low quality or malfunctioning model, to mishandle the tape and damage it by creasing it, frilling (stretching) its edges, or even breaking it.

=== DVD ===
By the advent of [[DVD]], LaserDisc had declined considerably in popularity, so the two formats never directly competed with each other.
[[File:LDDVDComparison-mod.png|thumb|right|A Laserdisc (left) is much bigger than a DVD (right)]]
LaserDisc was a [[composite video]] format: the luminance (black and white) and chrominance (color) information were transmitted in one signal, separated by the receiver. While good [[comb filter]]s could separate the signals adequately, the two signals could not be ''completely'' separated. On [[DVD-Video]], images are stored in the [[YCbCr]] format, with the chroma information being entirely discrete, which results in far higher fidelity, particularly at strong color borders or regions of high detail (especially if there is moderate movement in the picture) and low-contrast details such as skin tones, where comb filters almost inevitably smudge some detail.

In contrast to the entirely digital DVD, LaserDiscs used only analog video. As the LaserDisc format was not digitally encoded and did not make use of compression techniques, it was immune to video [[macroblocking]] (most visible as blockiness during high motion sequences) or [[color banding|contrast banding]] (subtle visible lines in gradient areas, such as out-of-focus backgrounds, skies, or light casts from spotlights) which could be caused by the [[MPEG-2]] encoding process as video is prepared for DVD. Early DVD releases held the potential to surpass their LaserDisc counterparts, but often managed only to match them for image quality, and in some cases, the LaserDisc version was preferred. Proprietary human-assisted encoders manually operated by specialists could vastly reduce the incidence of artifacts, depending on playing time and image complexity. By the end of LaserDisc's run, DVDs were living up to their potential as a superior format.

DVDs use compressed audio formats such as [[Dolby Digital]] and [[Digital Theater System|DTS]] for multichannel sound. Most LaserDiscs were encoded with stereo (often Dolby Surround) CD&nbsp;quality audio 16bit/44.1&nbsp;kHz tracks as well as analog audio tracks.<ref name="AllforMP3" />

DTS-encoded LaserDiscs have DTS soundtracks of 1,235&nbsp;kbit/s instead of the reduced bitrate of 768&nbsp;kbit/s commonly employed on DVDs with optional DTS audio.

=== Advantages ===
LaserDisc players could provide a greater degree of control over the playback process. Unlike many DVD players, the transport mechanism always obeyed commands from the user: pause, fast-forward, and fast-reverse commands were always accepted (barring malfunctions). There were no "User Prohibited Options" where content protection code instructed the player to refuse commands to skip a specific part (such as fast forwarding through [[copyright]] warnings). (Some DVD players, particularly higher-end units, do have the ability to ignore the blocking code and play the video without restrictions, but this feature is not common in the usual consumer market.)

With CAV LaserDiscs, the user could jump directly to any individual frame of a video simply by entering the frame number on the remote keypad, a feature not common among DVD players. Some DVD players have a cache feature, which stores a certain amount of the video in RAM, which allows the player to index a DVD as quickly as an LD, even down to the frame in some players.

Damaged spots on a LaserDisc could be played through or skipped over, while a DVD will often become unplayable past the damage. Some newer DVD players feature a repair+skip algorithm, which alleviates this problem by continuing to play the disc, filling in unreadable areas of the picture with blank space or a frozen frame of the last readable image and sound. The success of this feature depends upon the amount of damage. LaserDisc players, when working in full analog, recover from such errors faster than DVD players.

Similar to the [[Compact disc|CD]] versus [[LP record|LP]] sound quality debates common in the [[audiophile]] community, some videophiles argue that LaserDisc maintains a "smoother", more "film-like", natural image while DVD still looks slightly more artificial. Early DVD demo discs often had compression or encoding problems, lending additional support to such claims at the time. The video [[signal-to-noise ratio]] and bandwidth of LaserDisc are substantially less than those of DVDs, making DVDs appear sharper and clearer to most viewers.

Another advantage, at least to some consumers, was the fact that any sort of [[Copy protection#Anti-piracy|anti-piracy]] technology was purely optional. It was claimed that [[TiVo Corporation|Macrovision]]'s [[Copyguard]] [[Copy protection|protection]] could not be applied to LaserDisc, due to the format's design. The [[vertical blanking interval]], where the Macrovision signal would be implemented, was used for timecode and frame coding as well as player control codes on LaserDisc players. Due to its relatively small market share, there was never a push to redesign the format despite the obvious potential for piracy. The industry simply decided to engineer it into the [[DVD]] specification.

LaserDisc's support for multiple audio tracks allowed for vast supplemental materials to be included on-disc and made it the first available 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 (''[[King Kong (1933 film)|King Kong]]'' being the first release to have an [[audio commentary]] track included),<ref>{{Cite magazine|url=https://books.google.com/books?id=sQ0EAAAAMBAJ&pg=PA46|title=Quality is the Trademark of Criterion Collection DVDs|last=Neopolitan|first=Matt|date=May 17, 2003|magazine=Billboard|page=46|language=en}}</ref><ref>{{Cite web|url=https://www.denverpost.com/2005/08/24/if-dvd-killed-the-film-star-criterion-honors-the-ghost/|title=If DVD killed the film star, Criterion honors the ghost|date=August 24, 2005|website=The Denver Post|language=en-US|access-date=November 11, 2019}}</ref> and for setting the standard by which future "Special Edition" discs were measured. The disc provided interviews, commentary tracks, documentaries, still photographs, and other features for historians and collectors.

=== Disadvantages ===
Despite the advantages over competing technology at the time (namely VHS and [[Betamax]]), the discs were heavy—weighing about {{convert|250|g|oz}} each—and cumbersome, were more prone than a VHS tape to damage if mishandled, and manufacturers did not market LaserDisc units with recording capabilities to consumers. Also, because of their size, greater mechanical effort was required to spin the discs at the proper speed, resulting in much more noise generated than other media.

The space-consuming analog video signal of a LaserDisc limited playback duration to 30/36&nbsp;minutes (CAV NTSC/PAL) or 60/64&nbsp;minutes (CLV NTSC/PAL) per side, because of the hardware manufacturer's refusal to reduce line count and bandwidth for increased playtime, (as was done in VHS; VHS tapes had a 3&nbsp;MHz video bandwidth, while LaserDisc preserves the full 6&nbsp;MHz bandwidth and resolution used in [[NTSC]] broadcasts). After one side finished playing, a disc had to be flipped over to continue watching a movie, and some titles filled two or more discs, depending on the film's runtime and whether or not special features are included. 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 this was accompanied by a pause in the movie during the side change.

In the event the movie was longer than what could be stored on two sides of a single disc, manually swapping to a second disc was required at some point during the film (one exception to this rule was the Pioneer LD-W1, which featured the ability to load two discs and to play each side of one disc and then to switch to playing each side of the other disc). In addition, perfect still frames and random access to individual still frames was limited only to the more expensive CAV discs, which only had a playing time of approximately 30 minutes per side. In later years, Pioneer and other manufacturers overcame this limitation by incorporating a digital memory buffer, which "grabbed" a single field or frame from a CLV disc.

The analog information encoded onto LaserDiscs also did not include any form of built-in checksum or error correction. Because of this, slight dust and scratches on the disc surface could result in read errors which caused various video quality problems: glitches, streaks, bursts of static, or momentary picture interruptions. In contrast, the digital MPEG-2 format information used on DVDs has built-in error correction which ensures that the signal from a damaged disc will remain identical to that from a perfect disc right up until the damage to the disc surface prevents the laser from being able to identify usable data.

In addition, LaserDisc videos sometimes exhibited a problem known as "crosstalk". The issue could arise when the laser optical pickup assembly within the player was out of alignment or because the disc was damaged or excessively warped. But it could also occur even with a properly functioning player and a factory-new disc, depending on electrical and mechanical alignment problems. In these instances, the issue arose due to the fact that CLV discs required subtle changes in rotating speed at various points during playback. During a change in speed, the optical pickup inside the player might read video information from a track adjacent to the intended one, causing data from the two tracks to "cross"; the extra video information picked up from that second track shows up as distortion in the picture which looks reminiscent of swirling "[[barber pole]]s" or rolling lines of static.

Assuming the player's optical pickup was in proper working order, crosstalk distortion normally did not occur during playback of CAV-format LaserDiscs, as the rotational speed never varied. If the player calibration was out of order, or if the CAV disc was faulty or damaged, other problems affecting tracking accuracy could occur. One such problem was "laser lock", where the player read the same two fields for a given frame over and over, causing the picture to look frozen as if the movie were paused.

Another significant issue unique to LaserDisc involved the inconsistency of playback quality between different makers and models of player. On the majority of televisions, a given DVD player will produce a picture that is visually indistinguishable from other units; differences in image quality between players only becomes easily apparent on larger televisions, and substantial leaps in image quality are generally only obtained with expensive, high-end players that allow for post-processing of the MPEG-2 stream during playback.

In contrast, LaserDisc playback quality was highly dependent on hardware quality, and major variances in picture quality appeared between different makers and models of LaserDisc players, even when tested on low- to mid-range televisions. The obvious benefits of using high-quality equipment helped keep demand for some players high, while also keeping pricing for those units comparably high: in the 1990s, notable players sold for anywhere from US$200 to well over $1,000, while older and less desirable players could be purchased in working condition for as little as $25.

==== Laser rot ====
{{Main|Disc rot#Laser rot}}

Many early LaserDiscs were not manufactured properly. The adhesive that was used contained impurities which were able to penetrate the lacquer seal layer and chemically attack the metalized reflective aluminum layer, altering its reflective characteristics. This, in turn, deteriorated the recorded signal. This was a problem that was termed "laser rot" among LaserDisc enthusiasts (also called "color flash" internally by LaserDisc pressing plants). Some forms of laser rot could appear as black spots that looked like mold or burned plastic which caused the disc to skip and the video to exhibit excessive speckling noise. But, for the most part, rotted discs could actually appear perfectly fine to the naked eye.

Later optical standards have also been known to suffer [[Disc rot|similar problems]], including a notorious [[Compact disc bronzing|batch of defective CDs manufactured by Philips-DuPont Optical]] at their Blackburn, Lancashire facility in England during the late 1980s/early 1990s.