DVD glossary

Image

Fully premastered data assembled in the exact format for recording.

Incremental

Recording method allowing subsequent append or overwrite operations without reformatting or loss of adjacent pre-recorded information.

Index

Searchable points within a CD track, up to 99 index points per track.

Indexing

Creation of a data index to speed up search and retrieval.

Indirection

Method whereby fixed virtual addresses are mapped into variable logical locations.

Information Area

One area of a physical track consisting of one lead-in (with TOC), one program area, and one lead- out.

Information Layer

Physical layer of a CD or DVD disc that contains optically recoverable data after replication or recording.

Injection Molding

Replication involving injection under pressure of molten plastic into the cavity of a mold followed by cooling and removal of the solidified part that retains a replica of the mold.

Interchange

Capability of media to function properly in various systems.

Interleaving

A physical process rendering data more immune to burst errors whereby bytes from one input group are assigned to multiple output groups upon recording using a precisely defined method. De-interleaving during reading reverses the interleaving process, assembling data while dispersing read errors (also see CIRC.)

Or, a logical process of recording multiple files whereby each file is divided into extents, each containing a fixed number of blocks, that are recorded in a predetermined pattern having a fixed spacing between extents, and are alternated with extents of other files. Padding extents may be utilized if files are not of the same size.

Intersymbol Interference

Unwanted signal from adjacent information on the same track.

ISO

International Organization for Standardization comprised of national and regional member bodies and headquartered in Geneva, Switzerland. This non-governmental organization was established in 1947, and selected ISO from the Greek isos meaning equal, as in isothermal.

ISO 9660

International standard defining logical volume and file structure requirements for CD-ROM.

ISO/IEC 10149

International standard defining data interchange requirements for CD-ROM.

ISO/IEC 16448

International standard defining data interchange requirements for DVD-ROM.

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. (See also Multiple Audio Tracks)