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DAT -- The file type used for video data on a Video CD disc. Contains MPEG-1 video.

Digital Theater System -- See DTS.

disc -- Term commonly used to refer to optical storage devices such as DVD and CD. See also disk.

disc image -- A single file that contains the data for a complete DVD production. A disc image can be burned very efficiently to a DVD disc because it is in exactly the format that the data will be stored on a DVD. The disc image can be recorded directly to DVD to create the proper data structures and DVD volume directories. It also can be transferred to DLT tape to be used at a replication facility to manufacture multiple copies of the disc. See also format.

disk -- Term commonly used to refer to magnetic storage devices such as hard disks. See also disc.

DLT -- Acronym for Digital Linear Tape. A half-inch magnetic tape format used extensively for computer file backup and retrieval. Commonly used for transferring premastered DVD productions to a replication facility for manufacturing.

Dolby Digital -- Also called AC-3. Multichannel surround-sound audio encoding, used for cinemas and the home. Supports one to five full-range channels, plus a Low-Frequency Effects (LFE) channel for carrying low bass sounds. The five channels are Front Left, Front Center, Front Right, Left Surround, and Right Surround. Full surround-sound Dolby Digital is referred to as "5.1," for these five channels plus ".1" for the low-frequency channel. DVD-Video discs for NTSC are required to provide at least one Dolby Digital or PCM audio track. PAL/SECAM discs are required to provide at least one Dolby Digital, PCM, or MPEG-2 audio track. Discs may also have a separate stereo track, or DVD players can downmix a surround-sound signal to stereo. See also Dolby Headphone, Dolby Surround, DTS, SDDS, virtual surround sound.

Dolby Headphone -- Audio signal processing that allows conventional stereo headphones to create a surround-sound effect. See also Dolby Digital, virtual surround sound.

Dolby Surround -- A method of processing audio to achieve four-channel surround sound with conventional analog audio signals. The signal sounds like normal stereo, with left and right channels when played back through a conventional stereo system. When played through an audio system equipped with a Dolby Surround Pro Logic decoder, it extracts the two additional channels, center and surround. See also Dolby Digital, virtual surround sound.

Dolby Surround Pro Logic -- The technology that decodes program material encoded in Dolby Surround format.

double-sided disc -- A DVD disc with both sides used for data storage (unlike a manufactured DVD-Video or CD Audio disc with one side used for the label). Often used to distribute two versions of a commercial movie, with a widescreen version on one side and a standard 4:3 aspect ration on the other. With both sides, the storage capacity doubles from 4.7 to 9.4GB (actually billion bytes). Also called DVD-10. See also dual-layer disc.

downmix -- To convert from a multichannel audio program to fewer channels. For viewers who not have a surround-sound audio system, DVD players can downmix the DVD soundtrack to two-channel analog stereo, so the DVD can be played on a television or stereo system.

DTS -- Acronym for Digital Theater Systems. A surround-sound audio system used in many movie theaters. An optional format for DVD-Video that requires a separate decoder. See also Dolby Digital, PCM.

dual-layer disc -- A DVD disc with two layers of data on a side, accessed by refocusing the laser beam through the top layer to read the second layer. Often used to distribute a commercial title that is too long for a single-sided DVD while avoiding the need to continue the movie on a second disc. With the second layer, the storage capacity almost doubles from 4.7 to 8.5GB (actually billion bytes). Also called DVD-9. See also double-sided disc.

duplication -- To record a small quantity of DVD (and CD) discs using a dedicated recorder. See also replication.

DVD -- Originally an acronym for Digital Versatile Disc (or Digital Video Disc). A family of optical disc formats used both for prerecorded content, especially movies, and as recordable media for consumer devices and computers (that is, DVD-ROM, DVD-R, DVD-RW, DVD-RAM). A family of data format standards for video, audio, and data storage (that is, DVD-Video and DVD-Audio) for consumer electronics products and computers. DVD discs are the same diameter as CD discs (120mm. or 12 cm, in diameter), and most formats hold 4.7GB (actually billion bytes) of data on a side. A smaller size mini-DVD disc is also used, especially in camcorders.

DVD-5 -- Single-sized DVD disc format, with a storage capacity of 4.7GB (actually billion bytes).

DVD-9 -- Dual-layer DVD disc format, with a storage capacity of 8.5GB (actually billion bytes).

DVD-10 -- Double-sided DVD disc format, with a storage capacity of 9.4GB (actually billion bytes).

DVD-Audio -- A DVD Forum-defined format for high-quality surround-sound audio. Also supports optional text, images, video, and menus. Manufactured or packaged with a version of the album in DVD-Video format. Currently designed for audiophiles, and not supported in many DVD players. See also DVD-Video, SACD.

DVD Authoring -- The process of creating a DVD production. This involves designing the overall navigational structure; preparing the multimedia assets (video, audio, images); designing the graphical look; laying out the assets into tracks, streams, and chapters; designing interactive menus; linking the elements into the navigational structure; and building the final production to write to DVD, CD, hard disk, or tape. Consumer DVD Authoring software applications automate much of this process, including compressing the input files into DVD formats and laying out menus with buttons linking to the assets. More professional DVD Authoring tools separate the asset encoding and premastering steps, and provide more control over the DVD design - including button highlights and programmable scripts with navigation commands.

DVD Forum -- An industry consortium of international hardware manufacturers, software firms, and other DVD-related companies that developed the initial standards for the DVD physical disc and logical data formats.

DVD-Multi -- An umbrella DVD Forum-sponsored logo to identify DVD products, players and recorders, that support DVD-R, DVD-RW, and DVD-RAM formats.

DVD on CD -- A CD disc containing a DVD-format directory (VIDEO_TS) and files. Storing the contents of a DVD disc on a CD provides a convenient and less-expensive way to share a short DVD production (about 18 minutes at reasonable quality). DVD on CD discs can be played on a computer with DVD player software, but typically do not play on set-top DVD players. To make these discs more universally playable on any computer, some DVD authoring tools provide the option to include a DVD player software application on the CD disc. See also Video CD.

DVD player -- Either a consumer electronics hardware product designed to connect to a television set to play back DVD movies (a set-top DVD player) or a computer software application that plays DVD movies from a computer DVD drive (a DVD player application). See also DVD recorder.

DVD player application -- A computer software application that plays DVD movies from a computer DVD drive. See also set-top DVD player.

DVD-R -- DVD Recordable. The DVD Forum-defined write-once DVD format. Because the data cannot be erased, the DVD-R is useful for making permanent backups. Recordable discs are more compatible with set-top DVD players than rewritable discs. See also DVD-R for Authoring, DVD-R for General, DVD+R, DVD-RW.

DVD-R for Authoring -- Recordable DVD format for professional authoring use. Higher-cost discs that support the professional content-protection features. See also DVD-R for General.

DVD-R for General -- Recordable DVD format for general consumer use. Lower-cost discs that do not support the professional content-protection features. See also DVD-R for Authoring.

DVD+R -- Alternate DVD - Recordable write-once format developed by the DVD+RW Alliance. See also DVD-R, DVD+RW.

DVD-RAM -- DVD Random-Access Memory. The DVD Forum-defined, random-access DVD data format. Designed for data storage applications, with the capability to be accessed like a hard disk by reading and writing randomly, and with built-in error correction and defect management. Whereas DVD-RW discs can be overwritten 1000 times, DVD-RAM is designed to be written more than 100,000 times. See also DVD-R, DVD-RW.

DVD recorder -- A consumer electronics hardware product that acts like a digital VCR. Records television programming and/or input video (such as from a camcorder) to DVD disc. Some DVD Authoring computer software applications also can record directly from video input to a DVD drive. See also set-top DVD player.

DVD-ROM -- DVD Read-Only Memory. The DVD Forum-defined, read-only DVD format. Used for prerecorded audio and data. Also the computer-readable content on a DVD-Video disc. See also DVD-R.

DVD-RW -- DVD ReWritable. The DVD Forum-defined, re-recordable DVD format. Like CD-RW, rewritable discs can be reused, but are more expensive than recordable, and are less compatible with set-top players. See also DVD-R, DVD+RW, DVD-RAM.

DVD+RW -- Alternate DVD ReWritable format developed by the DVD+RW Alliance. Intended to replace the capabilities of DVD-RW and DVD-RAM and also provide higher compatibility with set-top players. See also DVD+R, DVD-RW.

DVD+RW Alliance -- An industry consortium developed the alternate recordable DVD formats, DVD+R and DVD+RW ("DVD plus"). See also DVD Forum.

DVD@ACCESS -- Mechanism for linking from a DVD production to a website. Developed by Apple and supported in DVD Studio Pro. See also enhanced DVD, Web DVD.

DVD Volume -- The DVD disc directory structure and files. You can create a DVD Volume on hard disk to play and test a project with a DVD player software application or burn the same files to a DVD disc. The DVD Volume is stored under a VIDEO_TS directory for the DVD-Video format. It includes Video Object (VOB) files with the actual multimedia data, video and audio; plus associated navigation information (IFO) and backup (BUP) files that describe their contents. These files are created for each Video Title Set (VTS), with the data split into multiple VOB files so that each file is no larger than 1GB. See also layout.

DVD-Video -- A DVD Forum-defined format for movies on DVD, including high-quality video and surround-sound audio; interactive navigation with menus and programmable control; and multilanguage and alternate viewing support with multiple video, audio, and subtitle streams. See also DVD-Audio, DVD-ROM.

DVD-VR -- DVD Video Recording. A modified form of the DVD format used to provide enhanced recording capabilities on some DVD-RW video recorders. Not as compatible with all DVD-Video players.