27th Feb 2004

DVD Tech Terms

3-2 Pulldown
The process of transferring 24 frames-per-second (fps) film to 30 fps video. Every other film frame is held for 3 video fields resulting in a sequence of 3 fields, 2 fields, 3 fields, 2 fields, etc.

4:2:2 Ratio
The sampling ratio used in the D1 (CCIR 601) digital video signal. For every 4 samples of luminance there are 2 samples each of R-Y (Red minus Luminance) and B-Y (Blue minus luminance).

5.1 Channel Surround Sound
Term used to describe a discrete six-channel surround sound, where the “5” corresponds to the five full-frequency (20Hz – 20kHz) channels (left, right, center, left surround, right surround) and the “1” refers to the Low-Frequency Effects (LFE) channel. Also 5.1 is a shorthand notation for a movie that has six-channel surround sound track. The number to the left of the dot is the number of full range channels and the number to the right of the dot signifies the presence of the dedicated subwoofer channel. A movie in 5.0 sound has five full range channels and no subwoofer track; a movie in 2.0 sound can be encoded in Dolby Surround or can just be stereo.

6.1 Channel Surround Sound
Dolby Digital & DTS Surround EX. Extension of 5.1 format. One more channel was added – Rear Center or Back Surround.

7.1 Channel Surround Sound
Dolby Digital & DTS THX Surround EX. Further extension of 5.1 surround sound format. Added in 6.1 Surround Rear Center channel was split into two channels – Back/Rear Left and Right to improve precision of surround sound.

AC-3 (now Dolby Digital)
Dolby Digital Surround Sound System. A digitally compressed audio format that can offer up to 6 separate digital audio channels. AC-3 is used for DVD-Video titles in the NTSC format. Standard digital data such as those used on CD would take up too much data on a DVD-Video, hence the use of a compressed audio format.

Aberration
A variation in the focus of a laser beam that causes the laser beam to become diffused. The aberrations cause focusing errors in the laser pick-up and cause the DVD to be miss-read.

Academy
Name for 1.33:1 aspect ratio film

AES
Abbreviation for Audio Engineering Society.

AES/EBU Interface
The standard for digital audio signal transmission for professional use developed by the Audio Engineering Society (AES) and the European Broadcasting Union (EBU). The AES/EBU systems use 110-ohm balanced XLR cables. The consumer version of the digital audio transmission standard is called S/PDIF.


Amplifier

A device that provides power to a signal, ultimately resulting in powering loudspeakers in the case of home theater.

Anamorphic
A wide-screen process of recording images, in video and film, so that each frame is horizontally compressed “squeezed” on a videodisc or strip of film. During playback, the image is expanded, restoring to its original size. Anamorphic film is best viewed in the wide-screen format. Brand marks include Cinemascope and Panavision.
This type of display format is optimized for playback on a TV with 16:9 aspect ratio. When wide-screen (letterboxed) movies are stored on VHS, Laserdisc, or non-anamorphic DVDs the horizontal scan lines that make up the black bars top and bottom are also stored. This is a waste of resolution because lines that could be used for the picture are being used to store the black bars. With anamorphic DVDs the widescreen picture is “squashed” to fit into a whole frame without black bars. If this were viewed without first “un-squashing”, the picture would be out of proportion e.g. the actors would look tall and thin. The DVD player must expand the picture to get it back to the original proportions and then either send this picture to a widescreen 16:9 TV or add black lines top and bottom for a standard 4:3 TV. Basically, any DVD that is “enhanced for widescreen TVs” or is “anamorphic” will give better picture quality on widescreen TVs where the picture would otherwise have to be “zoomed” to fit the 16:9 frame.

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. Other examples include image flicker, color shift, loss of resolution or changes in aspect ratio. On DVD, artifacts are usually a symptom of poor mastering, poor playback equipment, or improper adjustment of your television monitor. Make sure to calibrate your picture using a test disc like Video Essentials if you feel you are seeing artifacts.

Aspect Ratio
The width-to-height ratio of a television screen, letterboxed image on that screen, or motion-picture theater screen. Typical TV sets have a 1.33:1(4:3) ratio, while wide-screen versions have a 1.77:1 (16:9) ratio. Common aspect ratios for film and video are 1.33:1 (Academy), 1.78:1 (widescreen TV and HDTV), and 2.35:1 (Cinemascope).
Video can be stored on a DVD in 4:3 or 16:9 format. DVD players can output video in four different ways:
– full frame (4:3 video for 4:3 display)
– letterbox (16:9 video for 4:3 display)
– pan & scan (16:9 video for 4:3 display)
– wide screen (16:9 video for 16:9 display)
Letter box is when you have the black bars at the top and the bottom of your TV, Pan and scan is where the picture has been modified to fit your TV, i.e. chopping off the sides of the frame.

Audio Frequency

Frequencies within the range of human hearing (20 Hz to 20kHz).

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.

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.

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

  1. The amount of data that can be transferred or processed per unit of time.
  2. The range of frequencies a device operates within. The wider the bandwidth, the better the performance. Bandwidth is measured in kHz.

Bass
Frequencies in the lower part of the audio spectrum (20 Hz – 160 Hz).

Bi-directional Prediction
A form of compression in which the codec uses information not only from frames that have already been decompressed, but also from frames yet to come. The codec looks in two directions: ahead as well as back. This helps avoid large spikes in data rate caused by scene changes or fast movement, improving image quality.

Bit
A binary digit that indicates 0 for “off” and 1 for “on.”

Bitmap
An array of pixels.

Bits per Pixel

The number of bits used to represent the color information of a pixel. 1 bit per pixels allows using only 2 colors (usually black and white), 24 bits are used for True Color images (more than 16,7 million colors).

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.

Bitstream
A stream of data meant to be processed sequentially. Dolby Digital sound on a DVD is encoded onto a bitstream for processing.

Bonded Disc
In order to make a DVD more resilient, and less likely to warp, two 0.6mm layers are permanently bonded together. This also allows DVDs to be two-sided.

Book A
DVD Read only specification.

Book B
DVD Video specification. Organized into Physical, Logical, and Application sections.

Book C

DVD Audio specification.

Book D
DVD Write once specification.

Book E

DVD Rewritable specification.

Brightness
The value of a pixel along the black-white axis.

Calibration
Within the context of home video, calibration means adjusting the video display to adhere to a standard, usually NTSC. Within the context of audio, calibration means adjusting the sound level of each individual channel to match the level of all other channels.

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.

CBR
Constant bit rate compression. This indicates that in the encoding process the bit rate does not change, despite the simplicity or complexity of the image being encoded.

CEDIA

Custom Electronic Design and Installation Association.

CEMA
Consumer Electronics Manufacturers Association.

Center Channel

The channel in a surround sound setup that is directly in front of the viewer. The center channel speaker “anchors” sound that should be coming from the front of the screen. Most dialogs in a DVD are played through the center channel.

Center Speaker
The speaker in a surround sound system that handles dialogue and centrally positioned music and sound effects.

CGMS
Content Guard Management System. A copy protection method instituted for DVD to oversee digital copying of data. This method can dictate the number of digital-to-digital copies allowed of a specific title.

Channel
An individual (discrete) audio track. In the case of 5.1 Dolby Digital, there are six discrete channels.

Chapters
A method of organizing different scenes of a movie for easy navigation and access. 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).

Chrominance

The color component of a video signal that includes information about hue and saturation.

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.”

Clamping Area

The innermost area of disc used by CD/DVD player to grip and spin the disc during playback.

Closed Captions
A signal embedded in a video waveform, which, when fed into a captioning decoder, can product subtitles for the hearing impaired on screen.

Coaxial A/V Connection
The traditional RF connection for a Video signal. All DVD Players will have a coaxial output for purposes of hooking up to televisions without separate audio/video inputs.

Coaxial Connection
A type of connection used for consumer digital audio, which uses an RCA jack. The coaxial cable is an impedance-constant, two-conductor cable with either a stranded or solid core. For DVD digital audio, use a coaxial cable that has an impedance of 75-ohms (with 75-ohm connectors).

Codec
A software driver that is used to compress and decompress video, originally digitized from an analog source.

ColorStream
The component video connections for Toshiba DVD and TVs.

Color Temperature
The measure of a light source color in degrees Kelvin (K). Lower temperatures are redder in color, while higher temperatures are bluer in color. A properly calibrated display device measures 6500 degrees Kelvin.

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. Component video is often regarded as being the next step beyond S-video that can be found on the majority of DVD players, the benefits include improved color accuracy and less color bleeding.

Component Video Output
3 RCA or BNC connectors for the transfer of Component Video signal to TV or projector.

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.
All DVD players have this type of output. S-Video offers a better picture while Component video offers the best picture quality.

Composite Output
Traditional RF type signal. All DVD players have this type of output since not all TV’s have S-video or Component Video inputs.

Compress
The process of converting video and audio data into a more compact form for storage or transmission.

Connector
The terminating end of a cable.

Contrast
The range between the darkest tone and the lightest tone in an image.

Copy Protection
A process, like Macrovision, used to prevent illegal duplication of video (including DVD).

Constant bit rate (CBR)
Attribute of bitstream where the number of bits delivered to the MPEG System buffer (STD) and/or Video Buffer Verifier (VBV) is constant when measured over each picture period.

CSS
Content Scrambling System, a type of Digital copy protection sanctioned by the DVD Forum.


DAC

Digital to Analog Converter. A device that converts digital pulses to analog signals.

Data Stream
See bitstream.

Data rate
The speed in which data is accessed/read, usually measured in kilobytes per second.

Data recorded area
The area of disc that can be used to store information. Other areas of the disc are reserved for lead-in, lead-out, clamping, and labels.

Data Search Information (DSI)
Along with PGCI, these packets are part of the 1.00 mbit/sec overhead in video applications (Book B). These packets contain navigation information which makes it possible to search and maintain seamless playback of the Video Object Unit (VOBU). The most important field in this packet is the sector address where the first reference frame of the video object begins. Advanced angle change and presentation timing are included to assist seamless playback.

DDP
Disc Description Protocol is a small file(s) that describe how to master a data image file for optical disc (DVD or CD). This is ANSI industry standard developed by Doug Carson and Associates. This information is used in the mastering process by the Laser Beam Recorders.

Decode
The process of decompressing a video clip and then converting its color space of from YUV to RGB.

Decoder
A device that decodes compressed audio (e.g. Dolby Digital) or video (e.g. MPEG-2) and produces the original information.

Decompress

The process of converting video and audio data from its compact form back to its original form for playback.

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”.

Delta frame
A frame containing only the data that has changed since the last frame. Delta frames are an efficient means of compressing image data.

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 Comb Filter
To produce highly accurate Chrominance and Luminance signal separation, the chrominance and luminance signals are converted to a digital medium. This produces enhanced color purity and reduced dot craw.

Digitize

The process of converting an analog signal into digital data.

Digital Output

The majority of all DVD players will have at least a coaxial or optical output for sending the Dolby Digital bitstream to a Dolby Digital decoder. This decoder may be a stand-alone unit or built into a receiver.

Digital video

A video signal represented by computer-readable binary numbers that describe colors and brightness levels.

Dipole Speaker

A type of loudspeaker, designed to reproduce diffuse surround sound. This type of speaker has identical drivers that are 180 degrees out of phase with each other and radiate in opposite directions. This type of speaker is better suited for Dolby ProLogic surround sound than Dolby Digital.

Directory structure
For the video specification (Book B), this defines a common set of files that must be present on all DVD discs. Components include Root and Video_TS.

Direct View
A display device that uses tube technology, as opposed to front/rear projection technology.

Discrete Surround Sound
A type of surround sound where all channels are independent in their ability to play sound. Six channel surround sound (like Dolby Digital) can play six discrete channels to create an enveloping surround sound environment.

DLT

Digital Linear Tape, a high storage capacity (10-20 Gbytes) tape used as the input medium to master DVD. Media designated “type III” or “type IV” tapes are used for DVD

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 special edition will contain one or more of these behind-the-scenes features.

Dolby Digital (formerly AC-3)
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-frequency effects (LFE). Like Dolby Surround Pro Logic, it includes Left, Center and Right channels across the front of the room. Dolby Digital provides separate (discrete) left surround and right surround channels, for more precise localization of sounds and a more convincing, realistic ambience. 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 and HDTV and is optionally supported on Laserdisc.
Dolby Digital decoder is required for playback, although all DVD players will “downmix” the signal into two-channel surround if you don’t have the DD equipment.

Dolby Digital EX
See 6.1 Channel Surround Sound

Dolby Digital THX EX
See 7.1 Channel Surround Sound

Dolby Pro Logic
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.

Dolby Pro Logic II
The next generation of Dolby Surround Pro Logic decoding technology. Dolby Pro Logic II can create a “simulated” 5.1 channel surround environment from a 4-Channel Dolby Surround signal. Pro Logic II is able to decode the thousands of existing Dolby Surround movies and TV shows already on the shelf, compatibly, and with enhanced image stability. The improvements in decoding techniques mean that the discreteness of the sound field elements are better-preserved in the decoding process than was possible with the now universally standard Pro Logic technology, developed in the mid 80s. Pro Logic II also incorporates special features for controlling the overall spatial dimensionality and frontal soundfield imaging that are particularly suited for autosound applications.

Downmix
The ability to playback mono, stereo, or multi-channel surround sound from an encoded soundtrack, depending on the playback system.

DTS Digital Surround
A high data rate, 5.1 channel surround sound technology developed by Digital Theater Systems. DTS Digital Surround is an encode/decode system that delivers six channels of master-quality, 20-bit audio. In the encoding process, the DTS algorithm encrypts six channels of 20-bit digital audio information in the space previously allotted for only two channels of 16-bit linear PCM. Then during playback, the DTS decoder reconstructs the original six channels of 20-bit digital audio. Each of these six channels is audibly superior to the 16-bit linear PCM audio found on conventional compact discs. The DTS digital surround sound uses 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).
In order to listen to the DTS soundtracks on DTS DVD titles you need a DTS compatible player and DTS receiver/decoder. If you don’t have a player with a DTS digital output you can still use DTS titles but you won’t hear multi-channel audio, just PCM stereo or 3 channel Dolby Digital depending on the title. All DTS compatible players should be compatible with Dolby Digital however.

DTS Surround EX
See 6.1 Channel Surround Sound

DTS THX Surround EX
See 7.1 Channel Surround Sound

DTV

Digital Television. Applies to digital broadcasts in general and to the U.S. ATSC standard in specific. The ATSC standard includes both standard-definition (SD) and high-definition (HD) digital formats.

DVD
Digital Video Disc or Digital Versatile Disc. A high-density optical storage 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.

DVD-9
Single-sided/dual-layer DVD with 8.5 GB storage capability.

DVD-10
Double-sided/single-layer DVD with 9.4 GB storage capability.

DVD-18
Double-sided/dual-layer DVD with 17 GB storage capability.

DVD-Audio
Format of recording 16, 20 or 24 bit digital audio with a sample rate 44.1 – 192 kHz on DVD disc. DVD-Audio disc can also contain video, pictures or text.

DVD-R
Write-once type DVD-Recordable discs invented by Pioneer in 1998. This technology is used for master-disks recording.

DVD-RAM
DVD-Random Access Memory. Rewriteable type DVD disc with more than 2.6 GB or 4.7 GB (DVD-RAM Version 2) storage capacity per side supported by Panasonic, Hitachi and Toshiba. The main disadvantage of the technology – lack of backward compatibility, i.e. DVD-ROM drives and DVD players cannot read from DVD-RAM media.

DVD-ROM

DVD Read Only Memory. DVD-ROM is a version of DVD for computers, designed to replace the CD-ROM. It has the same capacity as DVD-Video that is far greater than normal CD-ROMs. To play DVD movies on a DVD-ROM drive you also need an MPEG-2 decoder board or software decoder.

DVD-ROM Features
DVD discs can 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 (PC Friendly Disks). 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.

DVD-RW
DVD-ReWritable. This format was developed by Pioneer and is partially compatible with modern DVD players and DVD-ROM drives. Can be used only for recording audio and video streams.

DVD+RW
Digital Versatile Disc plus Re-Writeable. This format is fully backward compatible with DVD players and DVD-ROM drives and can be used both for video recording and for data storage. Hewlett-Packard, Mitsubishi-Chemical/Verbatim, Philips, Ricoh, Sony, Yamaha and Thomson Multimedia support it. DVD+RW is still in development stage.

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.

Dynamic Range
The range between the loudest and quietest parts of an audio signal. TV sound is not very dynamic, with dialogue usually almost at the peak level of the signal. With film sound on DVD there is an large amount of headroom available for sounds louder that dialogue – up to 24dB. This is why the output level of a DVD player tends to be set low compared to that of a VCR.

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.

ECC/EDC
Error Correction Code/Error Detection Code. Codes specified in the color book standards and imbedded in DVD data which facilitate the reconstruction of data if read errors occur.

Encode

In the context of digital video, the process of converting the color space of a video clip from RGB to YUV and then compressing it.

Error Correction
A digital circuit that corrects errors during the retrieving/decoding process.

Field
One half of a video frame, consisting of every other row (scan line).

File
A multiple of logical blocks on disk.

File System

Means of identifying files and their sector number on disc.

Frame

A complete, individual picture in a motion video.

Frame rate

The number of frames per second at which a video clip is displayed.

FPS
Frames Per Second. Rate at which motion video frames are displayed.

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. Often (erroneously) used interchangeably with pan-and-scan.

Full motion video
Video that plays back at thirty frames per second (NTSC) or 25 frames per second (PAL).

Glitch
A noticeable audio or visual anomaly during DVD playback.

GOP
Group of Pictures.

HDTV
High Definition Television encompasses both analog and digital televisions that have a 16:9 aspect ratio and approximately 5 times the resolution of standard TV (double vertical, double horizontal, wider aspect).

Horizontal Resolution

This is the number of lines that run across the width of a TV. You get the clearest picture with a larger number. The main breakdown is as follows:
Standard VHS resolution – 220 horizontal lines
Laser disc – 425 horizontal line
DVD – 480-500 horizontal line

ID Error Correction (IEC)
2 special error correction bytes (IEC) that are added to each sector header.

Identification Data (ID)
32-bit field identifying the sector number within the disc volume.

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).

Interactive Games
Some DVDs now contain interactive games, though they are usually simple and playable only one or two times. 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. Most DVDs currently contain navigation menus, and menus are becoming more and more elaborate with music, graphics and animation.

Interframe compression
A form of compression in which the codec compresses the data within one frame relative to others. These relative frames are called delta frames.

Interlacing
The process of drawing a frame by alternately drawing the rows of each field, creating the illusion that the image is being redrawn twice as often as it actually is.

Intraframe compression
A form of compression in which the codec compresses the data within one frame relative only to itself. Key frames are compressed with intraframe compression because they must reconstruct an entire image without reference to other frames.

Isolated Music Score
A movie may have a 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.

JPEG
Joint Photographic Expert Group: a standard for compressing single images with high quality.

Jump
An anomaly that causes the DVD player to “skip” ahead.

Karaoke
A special DVD format that allows for certain special features. The audio portion of this format is distinctive in that it is intended for “Sing Along” formats and may include audio tracks for “Guide Vocals”, “Guide Melody”, “Chorus” and the main Karaoke left and right channels. The audio track for Karaoke in DVD-video is defined to be applicable for multi-channel setup with 5 channels maximum. When this vocal part is recorded mainly in track 4 and 5 except the main 2 channels, the users can enjoy many different playback modes by Karaoke type DVD players equipped with various audio ON/OFF switches

Key frame
A frame containing all the data representing an image, rather than just the data that has changed since the last frame. The first frame of every video file is a key frame; in addition, they occur throughout the file to refresh image quality and permit certain operations, such as random user access.


LaserDisc

A 12-inch optical disc originally called LaserVision. Laserdisc offers 425 lines of horizontal resolution, which results in picture quality that is superior to VHS tape, but not quite as good a s DVD (480 lines of resolution).

Laserrot

A physical problem with a disc, caused by a manufacturing defect, that causes a laserdisc to become unplayable.

Layer 0
In a dual layer disc, this is the layer closest to the optical pickup beam and surface of the disc. Dual layer discs are 10% less dense than single layer discs due to crosstalk between the layers.

Layer 1

In a dual layer disc, this is the deeper of the two layers.

Lead-in
Unused physical area at the start of the continuous track spiral.

Lead-out
Unused physical area at the end of the continuous track spiral.

Letterbox
A term used to describe the presentation of widescreen films on an Academy aspect ratio (1.33:1) display. Black bars are used at the top and bottom of the picture to create an image that is widescreen.

LFE

Low Frequency Effects. This the surround sound channel used in 5.1 channel surround sound (like Dolby Digital and DTS) used to reproduce low frequency (5-120Hz) sounds. A subwoofer is used to play back the sound.

Linear PCM
Coded audio representation that does not employ compression. Each sample is discretely coded.

Lossless compression
A compression algorithm that does not lose any of the original data during the compression process. The original image or sound is completely preserved.

Lossy compression
Compression after which some portion of the original data cannot be recovered with decompression. Such compression is still useful because the human eye is more sensitive to some kinds of information than others, and therefore does not necessarily notice the difference between the original and the decompressed image.

Luminance
The component of a video signal that includes information about its brightness.


Macrovision

An analog copy protection technology developed by Macrovision. It is widely used in VHS and has now been applied to DVD. When applied to DVD, it prevents unauthorized duplication by scrambling the recorded data, such that the recorded data cannot be viewed.

Matrix Decoding
A process of decoding multiple channels (i.e. four in the case of Dolby ProLogic) from a 2-channel source.

Matte
The “black bars” on a widescreen video being displayed on a 1.33:1 display (i.e. standard TV). “Soft” mattes are using 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.

Media Conversion
The process of converting data from one type of media to another for premastering and mastering.

Middle area
Unused physical area that marks the transition from layer 0 to layer 1. Middle Area only exists in dual layer discs where the tracks of each layer are in opposite directions.

Mono
Short for monaural. Sound that comes from a single channel.

MPEG

(1) Moving Picture Experts Group. Sets the standards for video compression. (2) An international standard for compressing motion pictures and video with high quality. In addition to compressing single images-frames-frames are compressed relative to each other as well.

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 DBS (satellite TV) and DVD.

Multichannel Surround Sound

Used to describe audio playback systems with more than two channels (stereo). Examples include Dolby Digital, Dolby ProLogic, DTS, and 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.

Multimedia
Information that combines some or all of text, still images, sound, animation, and video.

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

Multisession

The ability to update the disc’s table of contents file for CD-ROM.

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.

Native resolution
The resolution at which the video file was captured.

NTSC

NTSC stands for National Television System Committee, which devised the NTSC television broadcast system in 1953. The NTSC standard has a fixed vertical resolution of 525 horizontal lines stacked on top of each other, with varying amounts of ‘lines’ making up the horizontal resolution, depending on the electronics and formats involved. There are 59.94 fields displayed per second. A field is a set of even lines, or odd lines. The odd and even fields are displayed sequentially, thus interlacing the full frame. One full frame, therefore, is made of two interlaced fields, and is displayed about every 1/30 of a second.

Numerical Aperture (NA)
A number that represents the lens aperture of a laser pick-up device. The numerical aperture is a unitless measure of the light gathering capacity of the lens system and determines its resolving power and depth of field. A vacuum has NA of 1.0 by definition. The higher the number, the better.

NUON
NUON is the new media processor made by the VM Labs. NUON enhances the passive elements of digital video products such as DVD Players, digital set top boxes and digital satellite receivers, and transforms them into compelling interactive video entertainment systems. The NUON technology allows hardware manufacturers to replace their current media processors with a programmable, flexible solution to make movies better, bring music to the big screen, Internet access and games to the DVD Player. You can find more information about NUON at the NUON site.

Opposite track
Dual layer disc where layer 0 and layer 1 have opposite track directions. Layer 0 reads from the inside to outside of disc, whereas Layer 1 reads from the outside to the inside. The disc always spins clockwise, regardless of track structure or layers. This mode facilitates movie playback by allowing seamless transition from one layer to another.

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).

Outer diameter

Width of the disc. This is 12 cm for “normal” CDs and DVDs, and 8 cm for small CDs and DVDs.

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.

Pack

Collection of MPEG systems stream packets. In DVD, one pack is coded per sector.

Packet
In DVD, each packet consists of 2048 byte from one stream (1 of up to 8 audio streams, 1 video, 1 private VBI stream, etc.) aligned to a DVD sector. Some bytes of the packet are consumed by the MPEG-2 Systems Program stream header.

PAL

PAL stands for Phase Alternation by Line, and was adopted in 1967 as the standard for commercial television broadcasting in most of Europe, Australia, parts of Central and South America, and other countries. It has 625 horizontal lines making up the vertical resolution. 50 fields are displayed and interlaced per second, making for a 25 frame per second system. An advantage of this system is a more stable and consistent hue (tint).

Palette
A look-up table of color values.

Pan-And-Scan
Technology used to produce an Academy (1.33:1) 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.

Panavision
Brandmark for the processes of filming a widescreen (2.35:1) aspect ratio film onto 35mm film using anamorphic lenses.

Parallel track
Dual layer disc where layer 0 and layer 1 have the same clockwise (as seen from the readout side of the disc) spiral direction (inside radius to outside radius).

Parental Locks & Parental Control
This feature is particularly useful if you have children. It allows you to select the rating you would like to watch, according the rating you select the DVD player will jump over any unsuitable scenes. Most parental control features are accessible with the remote control and use a four-digit password.
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)

Part of title
Subset of a Title. Useful for designating a collection of video objects that belong to a common scene. Analogous to “Chapters” on analog video laserdisc.

PCM

Pulse Code Modulation. An uncompressed digital representation of an analog signal. This is the standard format for CD and DVD audio. CD is 16-bit and DVD can support up to 24-bit.

Perceptual Coding
Technique used by Dolby Digital to remove sound information that would not be detected by the human ear. This ability to reduce unnecessary sound results in greater compression.

Player
Embodiment of a DVD decoder system that executes the Navigation system and performs all decoding from the channel layer at least up to the track buffer layer.

Player Reference Model
Defines the ideal behavior of a DVD (compliant) Player.

Photo CD
Kodak’s Photo CD for representing 24-bit 4:2:0 YCbCr images hierarchically at resolutions of up to 3072×2048 pixels. Thumbnails image representation is also part of the Photo CD spec. Built upon CD-ROM XA.

Physical format

Low-level aspects for DVD specifying the layout of pits all the way up to the user bitstream layer.

Pit Art

A type of DVD labeling in which the pits are cut in a design to resemble writing or another image.

Pit Length
Arc length of pit along the direction of the track.

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
Picture element: the smallest independently accessible unit of a digital image.

Pixel color depth
The number of bits of color information per pixel. A system using 8 bits per pixel can display 256(28) colors, 16 bits per pixel can display 65,536(216) colors and 24 bits per pixel can display over 16.7 million colors. Twenty-four bit color is often called true color because the human eye can distinguish among approximately six million different colors, or fewer than are available in a 24-bit color system.

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 biographies and filmographies of the cast and crew and detailed notes on the production.

Program Chain Information (PGCI)

In pointer fashion, describes the physical sector locations of each program comprising the program chain. Sector addresses for non-seamless angle changes (user selected branch) and subpicture highlight control are included in the PCI packet. PGCI is part of the 1.00 mbit/sec user data overhead, along with DSI packets, that is removed prior to entering the system target decoder (STD) buffer.

Presentation Control Information (PCI)
Provides information about the timing and presentation (aspect ratio, angle, etc.) of a program.

Presentation Data
Information, such as video or audio samples, which are presented at a specified time.

Progressive Scan
A video scanning system that displays all lines of a frame in one pass as opposed to interlacing the lines (alternating the lines, showing half of the picture each pass).

Raw

A bitstream format in which the video data is uncompressed.

Reed-Solomon
Cyclical method of error correction.

Reed-Soloman Product Code
Two pass (row x col) application of Reed-Soloman code designed to exploit interleaving of data sectors.

Regional Coding
A provision in the DVD Specification that requires DVD players to be hard-coded to accept DVDs that is only meant to be played within one of six designated world regions. A Code 1 disc cannot be played in a Code 3 region for example. This technique was developed to enable Hollywood companies to release movies at different times in different regions.
The DVD regions are defined as:

  • Region 1 – United States of America, Canada
  • Region 2 – Europe, Greece, Turkey, Egypt, Arabia, Japan 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

Movies are released on DVD at different times around the world, typically America and Canada first, Australia and Japan 6 months later, and Europe 12 months after US release. In some instances, DVD movies are available for purchase in America and Canada before they are released in European cinemas.

Regional Coding Enhancement
Recently, the Motion Picture Association of American (MPAA) has developed a new system called Regional Coding Enhancement (RCE) which will be included on almost all new region 1 DVD releases. This new technology was created to prevent consumers with codefree DVD players from watching DVD discs purchased in North America. From now on, most region 1 DVD discs will be including this technology. As such, you may find in the future that some DVD discs bought in the United States will not work on your codefree DVD player.

Reserved bytes
6 bytes in the header of each DVD sector reserved for future use.

Resolution
The width and height of the video window, in pixels. DVD resolution is 720X480.

RF
Radio Frequency.

RGB
Red, Green & Blue. The three primary colors of light. A color model used in computer/monitor displays, in which different colors are specified according to the combination of their red, green and blue components.

RSDL
Reverse Spiral Dual Layer – a technique by which a movie is split across two layers of a single disc and is joined together for continuous playback. Allows longer movies (or movies with extra content) to be shown uninterrupted on a single side of a disc and twice (8.5 GB) the ordinary amount of DVD data per side. 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.

Run-length coding
Lossless compression method that exploits continuous samples with same value.

S/PDIF
Sony/Philips Digital Interface. The standard for transmitting digital data (like Dolby Digital) on consumer-grade components. Uses either a 75-ohm coaxial or TOSLINK optical cable.

Sampling
Process of creating a digital representation of an analog signal. Standard CD PCM is sampled at a rate of 44.1 kHz (44,100 “samples” of the sound are taken per second).

Saturation
The amount of gray, as opposed to hue, in a color-the intensity of the hue.

Scanning velocity
Rate at which the laser pickup beam travels along the spiral track.

SCART
The standard European AV connector/socket for TVs, VCRs, and DVD players.

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.

SDDS

Sony Dynamic Digital Sound. Sony’s discrete multi-channel surround sound available only in theaters. SDDS is available in 6-channel or 8-channel varieties.

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)

Sector

Logical collection of bytes at the data layer (after de-interleaving). At the physical layer, a sector consists of 38, 688 channel bits.

Sector information
Header field providing the sector number.

Sector number
A number that identifies the physical sector on a disc.

Sequence
MPEG definition of a set of coded pictures that are dependently coded. Within a sequence, all pictures adhere to a common bitrate (CBR), buffer size, picture size, aspect ratio, and frame rate.

Skip
Another DVD playback anomaly. See Jump.

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.

Sub-picture
A simple picture intended to be superimposed over the video. Variable in display size but bounded to CCIR 601 picture dimensions (720 x 480 for NTSC-rate displays or 720 x 576 for PAL-rate displays).

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. It’s a DVD half-disc. Two substrates, each 0.6 mm thick, are bonded together to form a 1.2 mm thick DVD disc.

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.

Subwoofer
A speaker designed to reproduce bass (low frequencies). Bass is not very directional, so most home cinema systems only need one mono bass channel.

Surround Speakers
Used in a ProLogic, Dolby Digital or other surround system. In a ProLogic system there is typically 5 speakers; center, front left, front right, and rear left and right carrying the same mono signal. In a Dolby Digital/DTS system the rear speakers carry a stereo signal, and there is usually an additional subwoofer. It is also possible to add additional subwoofers, dipole rear speakers and so on.

S-Video Output
Unlike the RGB Component output, S-Video modulates the video signal in its separate parts — chrominance (color) and luminance (light and dark). This makes for a more precise, detailed picture than RF.

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.

Telecine process
The process of turning film into video.

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. Encompassing theatrical presentation, home playback, and video mastering, “THX Certification” means many different things. Home theater components, for example, are tuned in such a manner to compensate for differences between theatrical and home playback. For more information, consult the THX website at .

Timbre Matching

Making sure that loudspeakers in a surround sound setup have equivalent tonal characteristics. This helps to ensure that sound is uniform as sound moves between speakers.

Titles and chapters

A “directory” structure that allows video programs to be divided up into titles and chapters. This allows easy navigation to a specific “chapter” or section of a movie for playback.

Toslink

A plastic fiber optic cable used for S/PDIF (e.g. DVD optical output).

Track pitch
Distance along radial vector between adjacent tracks.

Track buffer
In the player model, this unit is responsible for smoothing fluctuations in the user bitstream caused by irregular disc accesses. It also performs any regulation from the 11.08 mbit/sec constant user data rate to a variable rate MPEG stream (mux_rate) ranging anywhere from 1.0 to 10.8 mbit/sec. The mux_rate is always specified as a constant 10.08 mbit/sec, even though the sum of all the multiplexed streams (Video, Audio, Subpicture, VBI) may be much less (and prone to rapid fluctuation).

UDF
Universal Disc Format. Standard developed by the Optical Storage Technology Association. This file system was designed to be able to handle files from all other common file systems (computers), i.e. it can handle Mac resource forks and Windows95 long file names. UDF was also defined to be able to be enhanced for future systems. NSR ECMA 167 and ISO 13346 are predecessors to UDF.

Unidirectional prediction
A form of compression in which the codec uses information only from frames that have already been decompressed.

User Data
All data above the channel layer. This includes Video, Audio, Systems packet overhead, Subpictures, Navigation data, DSI packets, and File Management data. DVD reference data rate is specified as 11.08 mbit/sec.

User interface

A lowest common denominator of functions providing interactive selection of disc programming content. Includes: Ten keys and cursor keys, menu graphics and highlight areas, menu still picture with subpicture, and MPEG graphics.

Variable Rate Bitstream (VBR)
The flow of data being processed on a DVD can be variable, depending on the complexity of the information being processed. Fast moving, dynamic scenes require a high data rate, while a static (non-moving) image requires a lower data rate.

Vertical Blanking Interval (VBI)
In analog television, these are the first few scan lines within a field that do not contain picture information. They appear as static at the top of the image. Since these scan lines are not used to convey picture information, they become the natural place to insert side information such as teletext and closed caption bitstreams.

Video CD (VCD)
A digital video disc format using MPEG1 encoding, normally playable on DVD players. Its VHS quality picture and limited shortage capacity prevented it from ever becoming fully caught on.

Video Manager
Top level menu linking multiple tiles from a common point.

Video Manager Information (VMGI)

Points to the various titles that comprise the disc volume and identifies disc side and content type.

Video Object (VOB)

Usually a group of pictures.

Video Tile Set (VTS)
A maximum of 10 files (in ISO 9660 structure) may comprise a video tile set. A Management File precedes each video tile set. Each file in turn is limited to 1 GByte in size.

Video Tile Set Information (VTSI)
Describes the nature of the VTS.

Video_TS
UDF filename used for video directory on disc volume. Files under this directory name contain pointers to the sectors on the disc that hold the program streams.

Volume Management Information
Identifies disc side and content type.

Volume Space
Collection of sectors that make up the volume. Not all sectors on the disc comprise the volume. Some near the inner and outer spiral are used as leaders.

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.

XLR Connector
A 3-pin connector used for a balanced audio cable. Used in pro-audio equipment and AES/EBU digital audio.

Y/C
Another term for S-Video. The cable carries the luminance (“Y”) and chrominance (“C”) on separate channels.

YUV
A color model used chiefly for video signals in which colors are specified according to their luminance (the Y component) and their hue and saturation (the U and V components).

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