DVD glossary

Packet

Integral number of sectors forming a single unit of information that can be incrementally written or overwritten.

PAL

Phase Alternate Line video standard used in Europe and other parts of the world for composite color encoding, using 625 lines at 50 fields per second with a 4.438 MHz color subcarrier, although other scanning systems may be used.

Parity

Mathematical representation of data used for error detection or correction.

Partition

An extent of logical sectors within a volume; partitions may be allowed to overlap.

Path Table

A file in a single extent belonging to one directory hierarchy that contains contiguous records that fully describe the directory hierarchy.

PCA

Power Calibration Area of a recordable or rewritable disc that precedes lead-in and the PMA, where the optimum laser power level for writing can be determined by a recording drive.

Phase Change

State change of a recording layer caused by introduction of energy, resulting in information storage detectable by differences in optical properties of the physically different states.

Photo CD

Proprietary Eastman Kodak method of storing photographs on CD described in the Beige Book, using elements of Yellow Book, Orange Book, and CD-ROM XA.

PI or PO

See RS-PC.

Pit

Information area viewed as a depression from the label surface that can be sensed by an optical system.

Pitch

See Track Pitch.

PMA

Program Memory Area preceding lead-in of a recordable or rewritable disc containing a history of recorded track locations that are copied to the TOC upon finalization of the session or disc.

Polarization

Direction of the electric vector of an electromagnetic wave. Polarization is fixed for linear polarization or is rotating at right angles to the direction of propagation if circularly polarized.

Post-Gap

Two second area at the end of a CD program area or Mode change, encoded as null data or audio silence.

PQ Information

Subcode information determining track start points, control bits, timing, and other information.

Pre-Gap

Two second first part of a CD program area or track, normally encoded as null data or audio silence, but should contain track descriptor blocks if session-at-once or incremental track-at-once recording is used.

Pre-Groove

See Groove.

Premastering

Generating an image ready for mastering and replicating by formatting data into the exact sector, volume, and file structure required by the applicable standard.

Program Area

Region in the information area of the disc containing one or more logical tracks, each consisting of a pre-gap, followed by user data, and ending in a post-gap.

Protective Coating

Layer applied over the metal coating. Often a spin-coated UV-curable polymer.

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 3072x2048 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).