DVD Terminology
Anamorphic: A lens used to "squeeze" a widescreen image onto an Academy shaped frame during the filming of a movie and used to "unsqueeze" the image during playback. Brandmarks include Cinemascope and Panavision.
Anamorphic DVD: Term used for a video process utilizing the same principle of "squeezing" and "unsqueezing" a frame on a DVD. A 1.78:1 aspect ratio frame is squeezed into a 1.33:1 (4 x 3) shaped frame. During playback on a widescreen (1.78:1) TV, the picture is stretched horizontally to display the original high-resolution image. Only widescreen TVs can take advantage of anamorphic DVD. The term "enhanced for 16X9 televisions" or "enhanced for widescreen TVs" are other common terms for anamorphic DVD.
Artifact: An anomaly that occurs on a video image as a result of a problem in the film to video transfer, or problem with playback. A common artifact on DVD is pixelation, where individual pixels or groups of pixels produce an unnatural, "blocky" image.
Aspect Ratio: The ratio of width to height of a rectangle. Usually used when describing a screen used for playing back film or video. For example, a screen with an aspect ratio of 1.33:1 means that the width of the screen is 1.33 times longer than the height. Common aspect ratios for film and video are 1.33:1 ($ X 3 Full Screen) 1.85:1, 2.35:1 (16 x 9 Wide Screen)
Audio Streams: DVD has the ability to hold a maximum of eight audio streams on a single disc. This allows DVDs to have up to eight different language tracks for multiple languages and/or director’s commentary.
Authoring: In the case of DVD, it is the process of creating video (MPEG-2) from film.
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Average Bit Rate: Average volume of data (in a variable bit rate DVD system) measured over time. DVD uses variable bit rates for optimized storage capacity on a disc..78:1 (widescreen TV and HDTV), and 2.35:1 (Cinemascope).
B-frame: Bi-directional frame. The frame in an MPEG sequence created by comparing the difference between the current frame and the frames before and after it.
Bandwidth: The range of frequencies a device operates within. The wider the bandwidth, the better the performance. Bandwidth is measured in kHz.
Bit: A binary digit that indicates 0 for "off" and 1 for "on."
Bit Rate: An indication of the amount of data processed for some time period. Usually measured in bits per second (bps). Also called Data Rate. The higher the rate the better the picture/sound quality.
Bitstream: A stream of data meant to be processed sequentially. Dolby Digital sound on a DVD is encoded onto a bitstream for processing.
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Camera Angles: Scenes can be shot from different angles and played back to give the viewer the ability to see the scenes from different perspectives. DVD can support up to nine different camera angles to be recorded on a disc.
Chapter: DVDs are indexed by chapter, similar to the way a CD has a track. DVD players allow you to skip to a particular chapter (scene).
CinemaScope: The brandmark for the anamorphic film process developed by 20th Century Fox. The process was duplicated by Panavision, and is identified in film credits as "Filmed In Panavision
Component Video: Component video offers the highest video quality available on DVD. Component video is a 3-channel system that is either RGB or color-difference. DVD component video is color-difference. Signals using color-difference contain the color component of the picture minus the brightness component.
Composite Video: An analog signal that contains the combined signals for luminance (black and white) and chrominance (color) components. This is the standard for broadcast TV, VHS and Laserdisc.
Copy Protection: A process, like Macrovision, used to prevent illegal duplication of video (including DVD).
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Dolby Digital (formerly AC-3): Now known as Dolby Digital, this technology developed by Dolby Laboratories creates a digital bitstream of from one to six discrete source channels. When Dolby Digital is working in six-channel mode (5.1), five channels are full-frequency (20Hz-20kHz) while one channel is dedicated to low-frequencey effects (LFE). Dolby Digital uses a lossy compression (around 12 to 1) algorithm and usually has a bit rate of 384 Kbps. Dolby Digital is the standard audio format for DVD.
Dolby ProLogic: An active matrixed surround sound technology that derives four channels (left, right, center, surround) from a two-channel source. The left, right, and center channels are full-frequency, while the surround channel is limited frequency and mono. Dolby ProLogic is the home theater equivalent of Dolby Stereo for films.
DTS Digital Surround: A high data rate, 5.1 channel surround sound technology developed by Digital Theater Systems. The DTS digital surround sound used data rates of 1.44 Mbps, nearly four times higher than Dolby Digital (384 kbps). It also uses a significantly less compression ratio of (3 to 1 vs Dolby Digital’s 12 to 1). coder: A device that decodes compressed audio (e.g. Dolby Digital) or video (e.g. MPGE-2) and produces the original information
DVD: Digital Versatile Disc or Digital Video Disc. DVDs are a 6-inch disc capable of storing 4.7, 8.5, 9.4 or 17 gigabytes of data. DVD uses MPEG-2 video compression and Dolby Digital, or DTS audio.
DVD-5: Single-sided/single-layer DVD with 4.7 GB storage capability = roughly 133 mins of video (Silver In Colour)
DVD-9: Single-sided/dual-layer DVD with 8.5 GB storage capability = roughly 4 hours of video (Gold In Colour)
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DVD-10: Double-sided/single-layer DVD with 9.4 GB storage capability = roughly 133 minutes per Side (Silver In Colour)
DVD-18: Double-sided/dual-layer DVD with 17 GB storage capability = roughly 4 hours of video per Side (Gold In Colour)
DVD-R: Write-once type DVD-Recordable discs with 3.8 GB storage capacity per side.
DVD-RAM: Rewriteable type DVD disc with more than 2.6 GB storage capacity per side.
Error Correction: A digital circuit that corrects errors during the retrieving/decoding process.
FPS: Frames Per Second. Rate at which motion video frames are displayed.
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Frame: A complete, individual picture in a motion video. (PAL TV uses 25 Frames per second), NTSC TV uses 29.97 Frames Per Second and Film is nprmally 30 Frames Per Second
Full-Frame: Normally used to describe a Movie with a 1.33:1 (4 X 3) Aspect Ratio.
Glitch: A noticeable audio or visual anomaly during DVD playback can be caused by an authoring Problem, Manufacture Fault or a Dirty Disc or Lens or Faulty Player
GOP: Group of Pictures. (see MPEG –2)
I-frame: Also called I picture. I-frames identify the frame's background and are the initial reference frames for bi-directional (B-frame) and predicted frames (P-frame). Jump: An anomoly that causes the DVD player to "skip" ahead.
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. The menus are used for scene selections, video and audio setup and accessing special features.
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Laserrot: Some production runs of dual-layered DVDs result in a manufacturing defect where the adhesive used to bond the two layers together is either sub-standard or improperly applied. When the disc is new, the 'DVD Rot' is not visible and the error correction capabilities of DVD players compensate for the defect. Over time, however, the layers separate and the 'DVD Rot' increases in severity to the point where the disc becomes unplayable. It may become visible under certain lighting conditionsas a darkened area on the disc.
Letterbox: A term used to describe the presentation of widescreen films on (1.33:1 4 X 3) display. Black bars are used at the top and bottom of the picture to create an image that is widescreen.
Macrovision: Copy protection scheme used to protect DVDs and videotapes from illegal duplication.
Matte: The "black bars" on a widescreen video being displayed on a 1.33:1 (4 x 3) display (i.e. standard TV). "Soft" mattes are used in film playback to mask off the top and bottom of a film (1.33:1) before it is projected to make it appear widescreen. "Hard" mattes are actually printed on the film and cannot be removed during playback.
Mono: Short for monaural. Sound that comes from a single channel.
MPEG: Moving Picture Experts Group. Sets the standards for video compression.
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MPEG-1: A 30 fps system with a 6 to 1 compression ratio. MPEG-1 achieves approximately 1/4 the resolution of broadcast TV and is too slow for processing high quality moving images.
MPEG-2: The video compression technique used for DVD. MPEG compression squashes the picture by recording a complete reference frame and then only the changes for a group of Frames (GOP) the changes are then decoded back into full frames by the decoder engine of the DVD to produce a picture.
Multichannel Surround Sound: Used to describe audio playback systems with more than two channels (stereo). Examples include Dolby Digital, Dolby ProLogic, DTS, SDDS.
Multi-Language: This feature allows up to eight different audio tracks to be mastered on a single DVD. The user can then select the language track desired.
NTSC: Tthe standard for color television in North America. All DVD players sold in PAL countries (Australia) play both NTSC & PAL discs, but your TV monitor must be NTSC compatible in order to view in full colour. Please refer to your user manual or manufacturer to determine compatibility.
Optical Output: In the case of DVD, this connection is used to connect the DVD digital output to a surround sound processor via a TOSLINK cable to process DVD sound (Dolby Digital).
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P-frame: P-frames are constructed by analyzing previous frames and estimating where objects will be in the next frame. P-frames can predict where static and dynamic parts of the frame are. The P-frames are then used in the MPEG-2 decoding process to optimize motion transitions.
PAL: Phase Alternate Line. The standard for color television in Australia. All DVD players sold in PAL countries (Australia) play both NTSC & PAL discs, but your TV monitor must be NTSC compatible in order to view in full colour. Please refer to your user manual or manufacturer to determine compatibility.
Pan-And-Scan: Technology used to produce an Academy (1.33:1) (4 x 3) shaped image from a widescreen image. The process uses an Academy shaped "mask" to determine which part of the original film should be transferred to video. Depending on how wide the original film is, the Pan-And-Scan transfer can loose as much as 50% of the original image
Panavision: Brandmark for the processes of filming a widescreen (2.35:1) aspect ratio film onto 35mm film using anamorphic lenses.
Pits and Lands: The surface of the DVD has pits and flat surfaces (lands) that are read by the DVD player's laser beam and translated to a binary stream which is then decoded for audio and video playback.
Pixel: The smallest picture element of an image.
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Resolution: In DVD, resolution is the number of pixels in the height and width of the picture frame. DVD resolution is 720X480.
Regional Coding: A method by which DVD playback is restricted by geographic region. Studios use the regional coding to better control the timing of a DVD release around the world. The DVD regions are defined as:
Region 1 - United States of America, Canada
Region 2 - Europe, incl. France, Greece, Turkey, Egypt, Arabia and South Africa
Region 3 - Korea, Thailand, Vietnam, Borneo and Indonesia
Region 4 - Australia and New Zealand, Mexico, the Caribbean, and South America
Region 5 - India, Africa, Russia and former USSR countries
Region 6 - Peoples Republic of China
Skip: A DVD playback anomaly causing the program to skip to a new track or chapter.
Substrate: The clear material (polycarbonate) that surrounds and protects the stamped information on a DVD. The substrate is thin and helps the DVD ensure greater accuracy in the laser pick-up, because the laser is less likely to refract.
S-Video: A cable that carries the luminance ("Y") and chrominance ("C") on separate channels. Same as Y/C.
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Taking Care Of Your Discs: Because a DVD consists of two sides glued together (each a mere 0.6 mm thick), it can be susceptible to damage from bending and/or twisting. Also, though DVD error-correction encoding is nearly ten times better than those of audio CDs, because of DVD’s much higher compression ratio, shorter pit length and narrower tracks, severe scratches can create occasional problems in playback.
A good rule of thumb is to handle a DVD more carefully than a CD: Make contact only with the center hole and the outside edge of the disc. When removing a DVD from its case, press the button on the center hub and push downward. Using your other hand, gently remove the disc by its outer edge. Never remove a DVD from its package simply by prying up the outer edge of the disc unless the case does not have a Push to release centre.
Single-sided discs should be inserted into the player with titles/artwork facing up. Make sure the disc is seated properly inside the player before closing the tray.
Clean disc only with a damp, non-abrasive, lint-free cloth. Do not use any harsh or abrasive chemicals or cleaning agents. Wipe the disc carefully in a straight line from the inside hole to the outer edge. Never use a circular motion when cleaning a disc.
Do not stack your DVD discs. Always store the disc inside its protective case when not in use. And, of course, keep your DVD’s away from extreme heat, such as the back window of a car or the trunk area -- and keep them out of direct sunlight.
THX: A specification developed by Lucasfilm Ltd, designed to indicate that a product meets the minimum specifications for achieving high performance, to ensure a high-quality playback of a film or video.
Widescreen: An image with an aspect ratio greater than 1.33:1. Can include aspect ratios: 1.66:1, 1.85:1, and 2.35:1.
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