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Short for Digital Versatile Disc, Digital Video Disc
Dimensions 120 mm
DVD is a digital optical disc storage format (like a CD) and is one of the most popular video formats of the modern age. The technology was invented by Philips, Sony, Toshiba and Panasonic in 1995 and is still used presently as a popular way to deliver video and film to consumers. The format provides a higher storage capacity (dependent on technology) over CDs while still maintaining the same dimensions.
A single layer DVD has a capactiy of 4.7GB. This format is often used for shorter films (shorter run-time equals less space) or budget releases (where cost is a main factor and quality is spared). This format has one readable side and one unreadable side (which is used to print information about the film such as the title, region, runtime and film classification)
You can identify a single layer DVD in various ways:
A dual layer DVD has a capacity of 8.5-8.7GB. This format is the most common and is used for most feature film releases. This format has one readable side and one unreadable side (which is used to print information about the film such as the title, region, runtime and film classification)
You can identify a dual layer DVD in various ways:
A single layer, double sided DVD has a capacity of 9.4GB (4.7GB x 2). This format is rather uncommon and used for feature films. Both sides are readable by the laser, and so film information which would normally be on the face (unreadable side) of the disc is usually printed around the hub.
A dual layer, double sided DVD has a capacity of 17.08GB. This format is classed as "rare" by Wikipedia. It works in a similar way to a single layer, double sided disc in that both sides of the disc are readable and film information is normally printed around the disc hub.
The DVDplus is a dual-sided disc that combines the technology of DVD and CD in one disc. A DVD and a CD-compatible layer are bonded together to provide a multi-format hybrid disc.
DualDisc was a type of double-sided optical disc product. It featured an audio layer intended to be compatible with CD players (but not following the Red Book CD Specifications) on one side and a standard DVD layer on the other.
HD DVD (short for High Definition Digital Versatile Disc) is a discontinued high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format. It was abandoned in 2008 after a protracted format war with Blu-ray
The Combo disc is a dual sided disc with one side DVD and the other HD DVD
The Twin disc is a single sided disc that can have up to three layers, with up to two layers dedicated to either DVD or HD DVD.
Blu-ray or Blu-ray Disc (BD) is a digital optical disc data storage format, designed to supersede the DVD format, and is capable of storing several hours of video in high-definition (HDTV 720p and 1080p) and ultra high-definition resolution (2160p).
A 3D spec for Blu-ray discs.
Ultra HD Blu-ray is a digital optical disc data storage format that supersedes Blu-ray. Ultra HD Blu-ray discs are incompatible with existing Blu-ray players.
Being a common format there are many types of packaging for DVDs. Due to the fact that the media is the same dimensions as a Compact Disc (CD) some packaging types are the same as those found to deliver CD audio products.
As there are many different types of packaging for DVDs in the world, this section covers the most common types.
*(Also known as "keep case", poly-box or "Amaray")
This is the most common packaging type for DVDs. These usually measure 135mm wide, 190mm high and 14mm deep [See Exhibit A]. They can be various colours including transparent. Most cases open along the right hand side, to reveal the disc(s) placed into a disc holder on the right side and any extra booklets or paper inserts on the left handside (which may be held in place with two or three small clips) [See Exhibit B]. The disc is usually held in place by a push button, which when depressed releases the disc - however on multiple disc sets this button maybe static (unable to be depressed). On the note of multi-disc sets these cases usually can hold up to three discs in this format which may be achieved by stacking the discs on top of each other, or by a centrally hinged partition [See Exhibit C].
All standard DVD cases have the ability to hold a paper insert for the cover artwork. This is achieved by a thin transparent plastic layer that covers the DVD case, removing and inserting the paper is made possible by inverting the case (folding it back beyond 0 degrees) and then sliding the paper insert out with your finger.
|Exhibit A||This picture shows the dimensions of a standard DVD case in mm.|
|Exhibit B||This picture shows a standard DVD case open. As you can see the disc would be placed into the disc holder on the right hand side, which is then released when the central button is depressed. The left hand side has clips for paper items such as booklets or paper inserts.|
|Exhibit C||This picture shows a standard DVD case with a hinged partition. This version allows for one extra disc to be held in this tray. However some versions may have a partition which can hold two or three extra discs.|
This is another common packaging format for DVDs. Usually used for budget releases or boxsets, these cases are very similar to the standard side just they are much thinner (reducing the depth from 14mm to 7mm). These cases usually only compensate for a single disc, however two disc cases are available with disc holders on both sides of the case.
Alternate brand names - MCA DiscoVision, LaserVision Dimensons - 30cm, 20cm, 12cm
LaserDisc was the first optical format for the consumer market, originally sold beginning in 1978. A collaborative effort of MCA and Philips, the format was at first an entirely analog video/audio medium marketed to cinema enthusiasts and offering higher resolution video than competing formats such as VHS and Beta. Despite the better quality, LaserDisc never achieved the market penetration that VHS had, due both to production constraints and lack of recordability. Nevertheless, LaserDisc laid the bedrock for future optical formats, successfully incorporating digital audio, toggleable subtitles, and even HD video.
The first LaserDisc to be brought to market was the MCA DiscoVision release of Jaws in 1978.
LaserDisc releases were most commonly sold in the form of a 30cm circular disc composed of two single-sided aluminum discs sandwiched between polycarbonate. The aluminum discs held analog composite video encoded in pits and lands, similarly to successor media such as CDs and DVDs. LaserDiscs were also produced in 20cm size for short promotional video and music video releases. Later on, the CD Video format was introduced, which combined amounts of digital CD audio plus LaserDisc video on a 12cm, CD-sized disc.
NTSC LaserDisc video is encoded at 425 lines of horizontal resolution, while PAL LaserDisc video is encoded at 440 lines. This video would be stored on the LaserDisc in one of two ways:
Constant Angular Velocity (Standard Play) discs are spun in the player at a constant rotational speed - 1800rpm for NTSC discs, 1500rpm for PAL discs. This meant that one frame of video is displayed per revolution of the disc. Because of the constant rotational rate, the CAV format allows for "trick play" features, such as still frame and variable play speeds, as well as random access by frame number. The tradeoff is a decreased playback duration, roughly 30 minutes per side for NTSC and 36 minutes for PAL.
Constant Linear Velocity (Extended Play) discs are encoded so that the rotational speed of the disc will gradually decrease as the read head reaches the outside of the disc, so that the read head will move across the disc linearly at approximately the same speed. Trick play features are not found on CLV discs (most low and middle end players will also not display a freeze frame on pause, unlike with CAV discs), but the acceptable tradeoff is a longer playing time, with 60/64 minutes per side for NTSC/PAL, allowing most films released in this format to occupy a single disc.
Films would sometimes be released with one side CLV and the other side CAV, so that climactic moments of the film could be trick-played for freeze frame and slow-motion.
Upon introduction in 1978, the LaserDisc specification provided for a single composite video stream plus two analog audio streams allowing two mono tracks or a single stereo track. With the introduction of the Compact Disc, NTSC LaserDiscs would be able to hold an additional pair of digital audio tracks, for a total of four. PAL discs would be limited to a single pair of audio tracks, either analog or digital.
As audio technology developed, further options were incorporated into LaserDisc:
Dolby Digital was the first discrete surround sound solution for home theaters, introduced with Clear And Present Danger in 1995. It provides six discrete audio chanels for 5.1 surround sound.
The AC-3 surround track is stored on one of the analog audio tracks as a modulated digital signal. To properly play AC-3 audio, multiple conditions must be satisfied: a LaserDisc player that will output AC-3 audio, sometimes denoted with "AC-3 RF Out" printed on the front of the player, and demodulation hardware, either as a separate demodulation unit or with the capability built-in to the audio receiver. Some LaserDisc players can be modified to provide AC-3 RF output. These players will still require a separate demodulation solution.
DTS surround sound debuted in theaters with Jurassic Park in 1993, and would be incorporated into LaserDisc with the release of Jurassic Park in 1997.
DTS on LaserDisc provides for a similar 5.1 experience to AC-3, but at a higher bitrate. The DTS data is stored on both of the digital audio tracks on disc. Unlike AC-3, no demodulation hardware is required to play DTS audio, simply a receiver which will decode the DTS signal. Without a decoding receiver, however, the digital tracks will simply play static.
Many enthusiasts consider several DTS LaserDiscs to provide reference sound for their films, offering surround sound quality which was unrivaled for years, even after subsequent DVD releases.
As well as Format, Packaging is a required field for all releases submissions. The Packaging field allows you to pick one packaging type from a dropdown menu, and (optionally) add additional details in a free text description field. See descriptions of each packaging types here.
Laser rot is a phenomenon known to affect LaserDiscs. It manifests as video/audio distortion, usually appearing as speckling in the video and crackling in the audio. LaserDiscs from specific manufacturing sources seem more likely to manifest laser rot. MCA DiscoVision discs are notorious for varying derees of rot, as well as discs pressed at Sony DADC in Terra Haute. The condition appears to be caused by substandard manufacturing practices, leading to a breakdown of the adhesive which holds together the polycarbonate of the discs. The failing adhesive allows oxidation to occur in the aluminum discs between the polycarbonate, leading to data destruction.
As a contrast, several manufacturers, Kuraray being one, were known for their meticulous process and produced discs which to this day rarely exhibit laser rot. With proper storage discs such as these should not develop problems for the forseeable future.