Gservo
15th May 2002, 10:44 PM
Below is a Glossary of common DVD terms and definitions. This index is designed as a basic introduction, and all entries are listed alphabetically.
If you need further help, feel free to use the other Technical resources here in the navigation bar to your right.
16x9 Anamorphic Enhancement
The new DTV Television standard does not use a square (4:3) television set image area, but rather a 16:9 aspect ratio. This can present a problem when displaying DVD video on widescreen monitors. The full widescreen image is is "squished" horizontally on the disc, using what is known as an anamorphic process. Material stored anamorphically has to then be unsqueezed horizontally ("downconverted") by the DVD player be properly displayed on a standard 4:3 television. The DVD player removes every fifth line from the picture, and adds letterboxed bars to the top and bottom to display the wide image correctly.
Otherwise, the DVD player outputs the 16x9 "squished" image directly to a 16x9 player, which unsqueezes the image. The benefit of anamorphic enhancement is that it allows the image to be displayed at a higher resolution (hence better image quality), and still remain compatible with both 4:3 and 16x9 displays.
(see also Widescreen Cinema for more detailed 16x9 information)
Additional Languages : see Multiple Language Tracks
Anamorphic Widescreen : see 16x9
Aspect Ratio
The proportion of height to width of an image, expressed as width:height. For example, an image with a 1.85:1 aspect ratio and a height of 10 feet would be 18.5 feet wide. A 2.35:1 image and a height of 10 feet would be 23.5 feet wide. When dealing with theatrical images sizes, the height is universally expressed as a 1 (1.66:1, 2.20:1, etc.). However, in the world of television, this is not the case, and the standard television aspect ratio is expressed 4:3 (roughly 1.37:1), while the widescreen DTV standard is expressed as 16:9 (roughly 1.78:1).
Audio Commentary : see Multiple Audio Tracks
Cast & Crew Bios : see Production Notes
Commentary Track : see Multiple Audio Tracks
Chapter Selection : see Scene Access
Closed Captioning : see Subtitles
Deleted Scenes
Deleted Scenes are usually scenes that are removed from a program, for various reasons. Sometimes the scene was lousy, or was cut due to time restraints (or intrusive studio executives). Outtakes are usually goofs or bloopers that happened while filming the movie. Sometimes an outtake is considered a deleted scene as far as DVD packaging goes. Many times deleted scenes are reinserted into the film and the film is then called a "director's cut" or an "extended cut."
Descriptive Video Service
The Descriptive Video Service is an optional language track designed for the visually-impaired. It provides descriptive audio passages describing actions occurring on-screen.
Digital Stereo : see PCM
Director's Commentary : see Multiple Audio Tracks
Disc Specifications
DVD discs can come in a variety of storage capacities. Note that ALL players can play all disc specs, as required by the spec. (With dual-layer discs, note that there is often a slight pause during playback when the laser needs to refocus its beam onto the next layer. This is commonly known as a "layer change," and pause time varies by player.)
DVD-5 : Single Sided, Single Layer DVD - roughly 2 1/4 hours of video
DVD-9 : Single Sided, Dual Layer DVD - roughly 4 hours of video
DVD-14 : Dual Sided, Single Layer DVD - roughly 4 1/2 hours of video spread on two sides
DVD-16 : Dual Sided, One Side Single Layer and the other Dual Layer - roughly 6 1/4 hours of video spread on two sides
DVD-18 : Dual Sided, Dual Layer DVD - roughly 8 hours of video spread on two sides
Documentary
Due to DVD's large storage capabilities, documentaries are created to give you a look at what went on behind-the-scenes while filming a movie. Some documentaries can be as long as the film itself, or only a few minutes in length (such shorts are often called "featurettes"). Most better special edition will contain one or more of these behind-the-scenes features.
Dolby Digital
DVD can contain 5.1 channels of Dolby Digital sound; six sound channels (left, center, right, left surround, right surround, plus a low-frequency subwoofer channel, hence "5.1" not "6.0"). The "default" sound format for DVD is Dolby Digital. However, Dolby Digital is just a encoding process, thus there Dolby Digital sound streams on a DVD can range from one channel mono, to six channel 5.1. (See also DTS and PCM, as well as the July 20 Q+A for more information)
DTS (acronym for Digital Theater Systems)
One of the rival sound formats to Dolby Digital is called DTS (Digital Theater Systems). DTS is another six channel (5.1) format. DTS uses much more storage space on a disc than Dolby Digital. Some claim the sound is simply louder, not better, while others say they can tell an audible difference. Generally higher-priced decoders and DTS-enabled DVD players are needed to hear DTS sound. A DTS DVD MUST contain a Dolby Digital soundtrack or a PCM soundtrack in addition to the DTS soundtrack to maintain compatibility, in accordance with the DVD specification. (See also Dolby Digital and PCM)
Dual Layer Format : see RSDL
DVD-ROM Features
DVD discs can also be played on DVD-Video equipped personal computers. A new trend in the DVD world is to add computer-specific features to DVD-Video discs, that can only be played through DVD-ROM drives. These features can be screenplays, links to web sites (often called "web links"), advanced interactive games and text based information. These features are not accessible via DVD-Video players; one must have a DVD-ROM drive or DVD device with DVD-ROM capability.
Dynamic Pan & Scan
DVD has the capability to pan across a widescreen image horizontally via instructions coded into the video bitstream itself. This would allow for the widescreen and the Pan & Scan versions to be contained in the same space as one version of the film. Currently, it is decided that players lack the ability to perform these calculations uniformly and smoothly, so this feature may never see the light of day.
(Editor's Note: There have been some reports of overseas development in this area, but so far no major authorists have seriously committed to developing the capability further.)
Easter Eggs
Many DVDs contain "hidden features" stored on the disc, which can usually be accessed by some hidden icon on a menu screen. This practice is becoming more and more common, and is even becoming a promotional device for many distributors.
Featurette : see Documentary
Full Frame
Movies are shown theatrically in a widescreen presentation. One process of creating a widescreen film is to place "mattes" over the top and bottom of the 35 mm film frame (roughly 1.37:1) to alter the aspect ratio to 1.85:1 or other ratio. To avoid letterboxing bars on the top and bottom of a picture when displayed on a standard television, the original mattes are removed. Hence, the resulting video transfer shows more picture than was seen theatrically, and this process is called Full Frame. Most television and music programs are shot 1.37:1, and are also referred to as Full Frame or 4:3 presentations.
Interactive Games
Some DVDs now contain interactive games, though they are usually simple and playable only one or two times before boredom set sin. Oftentimes there will be a small "prize" for completing the game, such as an outtake, deleted scene or documentary. DVD-ROM capabilities allow for more complex games that are replayable, however, a DVD-ROM drive is needed to utilize such features. (see also DVD-ROM Features)
Interactive Menus
An interactive menu is a series of screens or pages (very similar to a web site) that allows the viewer to navigate and select different features on a DVD disc. Uses include selecting different scenes in a movie, and changing language or subtitles options, accessing special features, etc. 95% of all DVDs currently contain navigation menus, and the as the format matures, menus are becoming more and more elaborate with music, graphics and oftentimes striking animation.
Isolated Music Score
A movie may have a very elaborate and powerful orchestral soundtrack. This can be covered by dialogue and the action of the film. To allow for the viewer to hear this soundtrack without being diluted by action occurring during the film, an audio track may be used to store just the music minus all other sound elements. (See also Multiple Audio Tracks)
Language Tracks : see Multiple Audio Tracks
Layer Change : see Disc Specifications
Letterboxed : see Widescreen
Matting : see Full Frame
Music Video
Music videos have become a powerful promotion tool for films today, and have become a common supplement for DVDs as well. Music videos included on DVDs may even contain alternate commentary tracks or be presented with different sound formats.
Multiple Audio Tracks
A DVD disc can contain up to nine separate and continuous audio tracks. You can select which of the nine language tracks through the disc's menus or the remote control.
The value of such tracks is that they can be accessed instantly, and provide additional synched audio material in addition to the main soundtrack. Common uses are for foreign languages, alternate soundtracks, isolated musical scores or audio commentaries by the director, cast & crew or others associated with the material.
Multiple Video Tracks
One of the most interesting of DVD capabilities is its ability to show different angles of a scene or different versions of a scene. When it all comes down to the technical side of things, multiple angles are just multiple scenes filmed from a different camera angle, different. opening and closing credits, or additional storyboard or graphical content. These multiple video streams can be accessed instantly via a player's Angle function, and DVD discs can contain up to 8 separate video streams.
Music Only Track : see Isolated Music Score
Open Matte : see Full Frame
Outtakes : see Deleted Scenes
Pan & Scan
Movies are shown theatrically in a widescreen presentation. To allow this wide picture to fit onto the square-ish television screen, the sides of a picture are trimmed to allow the picture to fit. On some movies where the picture is very wide, nearly half the picture may be removed to recompose the film for the smaller aspect ratio. Because of this, you are not seeing the entire picture and the original vision of the filmmaker is often compromised.
Pan & Scan On The Fly : see Dynamic Pan & Scan
Parental Lock
A DVD player has two forms of parental lock. A DVD can be assigned a number designation based on how adult the content is (from 1 to 9), and the DVD player can be programmed (see your instruction manual) to lock out all titles above a certain rating unless a password is entered. This allows complete blackout of the entire program.
DVDs can potentially offer different edits as well, by utilizing the "seamless branching" feature. As of now, however, is rarely used, due to the general apathy on the part of the Hollywood creative community to allow consumers to "edit" films at will. (See also Seamless Branching and Multiple Video Tracks)
PCM
PCM sound is an uncompressed two-channel stereo or mono soundtrack (PCM is not used for multichannel sound). It requires more space due to the fact it is uncompressed. Usually, Dolby Digital is used, however some audiophiles prefer uncompressed 2-channel stereo, thus many music-oriented DVDs contain PCM tracks. DTS discs may contain a PCM track instead of a Dolby Digital track. (See also Dolby Digital and DTS)
Production Notes
Information about the production of a movie and the cast and crew for that movie may be contained as on-screen text in DVD menus. Information can include may biographies and filmographies of the cast and crew and detailed notes on the production. Oftentimes this information is provided via print in the form of a booklet or insert as well.
Region Code
DVD players are (usually) programmed to only play films designated for a certain part of the world. For example, in the United States of America, you would possess a Region 1 player and can only play discs designated for Region 1 use. All DVD players can play discs that do not contain Region coding or are coded as a Region 0 disc.
RSDL (acronym for Reverse Spiral Dual Layer disc)
Reverse Spiral Dual Layer (RSDL) allows longer movies to fit onto one side of a DVD, allowing continuous play for longer programs and no need to "disc flip." Usually, about 133 minutes of video can fit on a single layer. However, an RSDL disc can contain about 4 hours or more of interrupted video and audio. A dual-layer disc is easy to spot because it is gold in color, versus the silver shimmer of its single-layered brother. (See also Disc Specifications)
Scene Access
You do not have to watch a DVD from beginning to end, or use fast forward and rewind to access a particular scene. You may pick from a list of chapters to get to a certain scene, which is usually accessed via the menu, or by pressing the corresponding chapter number on the remote.
Seamless Branching
DVD has the capacity to switch instantaneously between separate and distinct video, audio and subtitle "streams" or tracks. This is done via complex coding commands, but unfortunately has not yet been widely exploited. (see also Multiple Video Tracks, Multiple Audio Tracks and Subtitles)
Still Gallery
DVD has the ability to display a single video frame at a time, for perfect still images. (This is quickly noticeable when the pause button is pressed during playback.) The best use of this capability is to take a collection of images and allow the viewer to page through them with the remote control skip buttons. Still frame files are generally used for behind-the-scenes photographs, promotional artwork, storyboards or conceptual art. A DVD can easily hold thousands of images or more.
Subtitles
A subtitle stream places text on the screen for the viewer to read, and is essentially used for dialogue. Subtitles can be in any number of languages, So that the viewer who does not speak the native language of the movie can view the movie and read what the actors are saying. DVD allows for up to 32 subtitle tracks.
Closed Captioning is an extended form of subtitling, wherein additional text is displayed with aural sound descriptions, to aid hearing-impaired individuals better understand action on screen. Note that a Closed Captioning decoder is required to receive captioning encoded on a disc. However, by law all new televisions must have built in Closed Captioning decoders. (See also Descriptive Video Service)
Teaser Trailer : see Theatrical Trailer
Theatrical Trailer
Hollywood Studios advertise their movies with theatrical trailers and television spots, or "coming attractions." Very short trailers that do not give much away about the plot are called Teaser Trailers, and are often created before the film is even shot! Longer advertisements that tell much more about the story are called Trailers or Theatrical Trailers. Short trailers shown on television are called TV Spots.
THX Certification
THX is not another sound format, but a set of quality control standards set by Lucasfilm. The full effect of a THX mastered disc is delivered using equipment that has been marked with the THX seal of approval. Even without THX equipment, a THX DVD is generally thought to be of better quality both in regards to sound and video, due to the strict THX codes of production and replication. (Editor's Note: Though this is not always the case...)
TV Spots : see Theatrical Trailer
Web Links : see DVD-ROM Features
Widescreen
A standard television is almost square. A movie shown in a theater is not shown square, but a wider rectangle of a vary aspect ratio (see also Aspect Ratio). To allow for a film to be shown on video in its original "widescreen" aspect ratio, black bars are placed on the top and bottom, thereby preserving the original width of the image (called "letterboxing"). DVD also allows for anamorphic widescreen transfers. (See also 16x9 Anamorphic Widescreen).
Zone Lock : see Region Code
If you need further help, feel free to use the other Technical resources here in the navigation bar to your right.
16x9 Anamorphic Enhancement
The new DTV Television standard does not use a square (4:3) television set image area, but rather a 16:9 aspect ratio. This can present a problem when displaying DVD video on widescreen monitors. The full widescreen image is is "squished" horizontally on the disc, using what is known as an anamorphic process. Material stored anamorphically has to then be unsqueezed horizontally ("downconverted") by the DVD player be properly displayed on a standard 4:3 television. The DVD player removes every fifth line from the picture, and adds letterboxed bars to the top and bottom to display the wide image correctly.
Otherwise, the DVD player outputs the 16x9 "squished" image directly to a 16x9 player, which unsqueezes the image. The benefit of anamorphic enhancement is that it allows the image to be displayed at a higher resolution (hence better image quality), and still remain compatible with both 4:3 and 16x9 displays.
(see also Widescreen Cinema for more detailed 16x9 information)
Additional Languages : see Multiple Language Tracks
Anamorphic Widescreen : see 16x9
Aspect Ratio
The proportion of height to width of an image, expressed as width:height. For example, an image with a 1.85:1 aspect ratio and a height of 10 feet would be 18.5 feet wide. A 2.35:1 image and a height of 10 feet would be 23.5 feet wide. When dealing with theatrical images sizes, the height is universally expressed as a 1 (1.66:1, 2.20:1, etc.). However, in the world of television, this is not the case, and the standard television aspect ratio is expressed 4:3 (roughly 1.37:1), while the widescreen DTV standard is expressed as 16:9 (roughly 1.78:1).
Audio Commentary : see Multiple Audio Tracks
Cast & Crew Bios : see Production Notes
Commentary Track : see Multiple Audio Tracks
Chapter Selection : see Scene Access
Closed Captioning : see Subtitles
Deleted Scenes
Deleted Scenes are usually scenes that are removed from a program, for various reasons. Sometimes the scene was lousy, or was cut due to time restraints (or intrusive studio executives). Outtakes are usually goofs or bloopers that happened while filming the movie. Sometimes an outtake is considered a deleted scene as far as DVD packaging goes. Many times deleted scenes are reinserted into the film and the film is then called a "director's cut" or an "extended cut."
Descriptive Video Service
The Descriptive Video Service is an optional language track designed for the visually-impaired. It provides descriptive audio passages describing actions occurring on-screen.
Digital Stereo : see PCM
Director's Commentary : see Multiple Audio Tracks
Disc Specifications
DVD discs can come in a variety of storage capacities. Note that ALL players can play all disc specs, as required by the spec. (With dual-layer discs, note that there is often a slight pause during playback when the laser needs to refocus its beam onto the next layer. This is commonly known as a "layer change," and pause time varies by player.)
DVD-5 : Single Sided, Single Layer DVD - roughly 2 1/4 hours of video
DVD-9 : Single Sided, Dual Layer DVD - roughly 4 hours of video
DVD-14 : Dual Sided, Single Layer DVD - roughly 4 1/2 hours of video spread on two sides
DVD-16 : Dual Sided, One Side Single Layer and the other Dual Layer - roughly 6 1/4 hours of video spread on two sides
DVD-18 : Dual Sided, Dual Layer DVD - roughly 8 hours of video spread on two sides
Documentary
Due to DVD's large storage capabilities, documentaries are created to give you a look at what went on behind-the-scenes while filming a movie. Some documentaries can be as long as the film itself, or only a few minutes in length (such shorts are often called "featurettes"). Most better special edition will contain one or more of these behind-the-scenes features.
Dolby Digital
DVD can contain 5.1 channels of Dolby Digital sound; six sound channels (left, center, right, left surround, right surround, plus a low-frequency subwoofer channel, hence "5.1" not "6.0"). The "default" sound format for DVD is Dolby Digital. However, Dolby Digital is just a encoding process, thus there Dolby Digital sound streams on a DVD can range from one channel mono, to six channel 5.1. (See also DTS and PCM, as well as the July 20 Q+A for more information)
DTS (acronym for Digital Theater Systems)
One of the rival sound formats to Dolby Digital is called DTS (Digital Theater Systems). DTS is another six channel (5.1) format. DTS uses much more storage space on a disc than Dolby Digital. Some claim the sound is simply louder, not better, while others say they can tell an audible difference. Generally higher-priced decoders and DTS-enabled DVD players are needed to hear DTS sound. A DTS DVD MUST contain a Dolby Digital soundtrack or a PCM soundtrack in addition to the DTS soundtrack to maintain compatibility, in accordance with the DVD specification. (See also Dolby Digital and PCM)
Dual Layer Format : see RSDL
DVD-ROM Features
DVD discs can also be played on DVD-Video equipped personal computers. A new trend in the DVD world is to add computer-specific features to DVD-Video discs, that can only be played through DVD-ROM drives. These features can be screenplays, links to web sites (often called "web links"), advanced interactive games and text based information. These features are not accessible via DVD-Video players; one must have a DVD-ROM drive or DVD device with DVD-ROM capability.
Dynamic Pan & Scan
DVD has the capability to pan across a widescreen image horizontally via instructions coded into the video bitstream itself. This would allow for the widescreen and the Pan & Scan versions to be contained in the same space as one version of the film. Currently, it is decided that players lack the ability to perform these calculations uniformly and smoothly, so this feature may never see the light of day.
(Editor's Note: There have been some reports of overseas development in this area, but so far no major authorists have seriously committed to developing the capability further.)
Easter Eggs
Many DVDs contain "hidden features" stored on the disc, which can usually be accessed by some hidden icon on a menu screen. This practice is becoming more and more common, and is even becoming a promotional device for many distributors.
Featurette : see Documentary
Full Frame
Movies are shown theatrically in a widescreen presentation. One process of creating a widescreen film is to place "mattes" over the top and bottom of the 35 mm film frame (roughly 1.37:1) to alter the aspect ratio to 1.85:1 or other ratio. To avoid letterboxing bars on the top and bottom of a picture when displayed on a standard television, the original mattes are removed. Hence, the resulting video transfer shows more picture than was seen theatrically, and this process is called Full Frame. Most television and music programs are shot 1.37:1, and are also referred to as Full Frame or 4:3 presentations.
Interactive Games
Some DVDs now contain interactive games, though they are usually simple and playable only one or two times before boredom set sin. Oftentimes there will be a small "prize" for completing the game, such as an outtake, deleted scene or documentary. DVD-ROM capabilities allow for more complex games that are replayable, however, a DVD-ROM drive is needed to utilize such features. (see also DVD-ROM Features)
Interactive Menus
An interactive menu is a series of screens or pages (very similar to a web site) that allows the viewer to navigate and select different features on a DVD disc. Uses include selecting different scenes in a movie, and changing language or subtitles options, accessing special features, etc. 95% of all DVDs currently contain navigation menus, and the as the format matures, menus are becoming more and more elaborate with music, graphics and oftentimes striking animation.
Isolated Music Score
A movie may have a very elaborate and powerful orchestral soundtrack. This can be covered by dialogue and the action of the film. To allow for the viewer to hear this soundtrack without being diluted by action occurring during the film, an audio track may be used to store just the music minus all other sound elements. (See also Multiple Audio Tracks)
Language Tracks : see Multiple Audio Tracks
Layer Change : see Disc Specifications
Letterboxed : see Widescreen
Matting : see Full Frame
Music Video
Music videos have become a powerful promotion tool for films today, and have become a common supplement for DVDs as well. Music videos included on DVDs may even contain alternate commentary tracks or be presented with different sound formats.
Multiple Audio Tracks
A DVD disc can contain up to nine separate and continuous audio tracks. You can select which of the nine language tracks through the disc's menus or the remote control.
The value of such tracks is that they can be accessed instantly, and provide additional synched audio material in addition to the main soundtrack. Common uses are for foreign languages, alternate soundtracks, isolated musical scores or audio commentaries by the director, cast & crew or others associated with the material.
Multiple Video Tracks
One of the most interesting of DVD capabilities is its ability to show different angles of a scene or different versions of a scene. When it all comes down to the technical side of things, multiple angles are just multiple scenes filmed from a different camera angle, different. opening and closing credits, or additional storyboard or graphical content. These multiple video streams can be accessed instantly via a player's Angle function, and DVD discs can contain up to 8 separate video streams.
Music Only Track : see Isolated Music Score
Open Matte : see Full Frame
Outtakes : see Deleted Scenes
Pan & Scan
Movies are shown theatrically in a widescreen presentation. To allow this wide picture to fit onto the square-ish television screen, the sides of a picture are trimmed to allow the picture to fit. On some movies where the picture is very wide, nearly half the picture may be removed to recompose the film for the smaller aspect ratio. Because of this, you are not seeing the entire picture and the original vision of the filmmaker is often compromised.
Pan & Scan On The Fly : see Dynamic Pan & Scan
Parental Lock
A DVD player has two forms of parental lock. A DVD can be assigned a number designation based on how adult the content is (from 1 to 9), and the DVD player can be programmed (see your instruction manual) to lock out all titles above a certain rating unless a password is entered. This allows complete blackout of the entire program.
DVDs can potentially offer different edits as well, by utilizing the "seamless branching" feature. As of now, however, is rarely used, due to the general apathy on the part of the Hollywood creative community to allow consumers to "edit" films at will. (See also Seamless Branching and Multiple Video Tracks)
PCM
PCM sound is an uncompressed two-channel stereo or mono soundtrack (PCM is not used for multichannel sound). It requires more space due to the fact it is uncompressed. Usually, Dolby Digital is used, however some audiophiles prefer uncompressed 2-channel stereo, thus many music-oriented DVDs contain PCM tracks. DTS discs may contain a PCM track instead of a Dolby Digital track. (See also Dolby Digital and DTS)
Production Notes
Information about the production of a movie and the cast and crew for that movie may be contained as on-screen text in DVD menus. Information can include may biographies and filmographies of the cast and crew and detailed notes on the production. Oftentimes this information is provided via print in the form of a booklet or insert as well.
Region Code
DVD players are (usually) programmed to only play films designated for a certain part of the world. For example, in the United States of America, you would possess a Region 1 player and can only play discs designated for Region 1 use. All DVD players can play discs that do not contain Region coding or are coded as a Region 0 disc.
RSDL (acronym for Reverse Spiral Dual Layer disc)
Reverse Spiral Dual Layer (RSDL) allows longer movies to fit onto one side of a DVD, allowing continuous play for longer programs and no need to "disc flip." Usually, about 133 minutes of video can fit on a single layer. However, an RSDL disc can contain about 4 hours or more of interrupted video and audio. A dual-layer disc is easy to spot because it is gold in color, versus the silver shimmer of its single-layered brother. (See also Disc Specifications)
Scene Access
You do not have to watch a DVD from beginning to end, or use fast forward and rewind to access a particular scene. You may pick from a list of chapters to get to a certain scene, which is usually accessed via the menu, or by pressing the corresponding chapter number on the remote.
Seamless Branching
DVD has the capacity to switch instantaneously between separate and distinct video, audio and subtitle "streams" or tracks. This is done via complex coding commands, but unfortunately has not yet been widely exploited. (see also Multiple Video Tracks, Multiple Audio Tracks and Subtitles)
Still Gallery
DVD has the ability to display a single video frame at a time, for perfect still images. (This is quickly noticeable when the pause button is pressed during playback.) The best use of this capability is to take a collection of images and allow the viewer to page through them with the remote control skip buttons. Still frame files are generally used for behind-the-scenes photographs, promotional artwork, storyboards or conceptual art. A DVD can easily hold thousands of images or more.
Subtitles
A subtitle stream places text on the screen for the viewer to read, and is essentially used for dialogue. Subtitles can be in any number of languages, So that the viewer who does not speak the native language of the movie can view the movie and read what the actors are saying. DVD allows for up to 32 subtitle tracks.
Closed Captioning is an extended form of subtitling, wherein additional text is displayed with aural sound descriptions, to aid hearing-impaired individuals better understand action on screen. Note that a Closed Captioning decoder is required to receive captioning encoded on a disc. However, by law all new televisions must have built in Closed Captioning decoders. (See also Descriptive Video Service)
Teaser Trailer : see Theatrical Trailer
Theatrical Trailer
Hollywood Studios advertise their movies with theatrical trailers and television spots, or "coming attractions." Very short trailers that do not give much away about the plot are called Teaser Trailers, and are often created before the film is even shot! Longer advertisements that tell much more about the story are called Trailers or Theatrical Trailers. Short trailers shown on television are called TV Spots.
THX Certification
THX is not another sound format, but a set of quality control standards set by Lucasfilm. The full effect of a THX mastered disc is delivered using equipment that has been marked with the THX seal of approval. Even without THX equipment, a THX DVD is generally thought to be of better quality both in regards to sound and video, due to the strict THX codes of production and replication. (Editor's Note: Though this is not always the case...)
TV Spots : see Theatrical Trailer
Web Links : see DVD-ROM Features
Widescreen
A standard television is almost square. A movie shown in a theater is not shown square, but a wider rectangle of a vary aspect ratio (see also Aspect Ratio). To allow for a film to be shown on video in its original "widescreen" aspect ratio, black bars are placed on the top and bottom, thereby preserving the original width of the image (called "letterboxing"). DVD also allows for anamorphic widescreen transfers. (See also 16x9 Anamorphic Widescreen).
Zone Lock : see Region Code