DVD Demystified

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Glossary
PES Packetized elementary stream. A single video or audio stream in
MPEG format.
PGCI Program chain information. Data describing a chain of cells
(grouped into programs) and their sector locations, thus composing a
sequential program. PGCI data is contained in the PCI stream.
phase-change A technology for rewritable optical discs using a physical
effect in which a laser beam heats a recording material to reversibly
change an area from an amorphous state to a crystalline state, or vice
versa. Continuous heat just above the melting point creates the crystalline
state (an erasure), while high heat followed by rapid cooling creates
the amorphous state (a mark). Other recording technologies
include dye-sublimation and magneto-optical.
physical format The low-level characteristics of the DVD-ROM and
DVD-Video standards, including pits on the disc, the location of data,
and the organization of data according to physical position.
picture In video terms, a single still image or a sequence of moving
images. Picture generally refers to a frame, but for interlaced frames, it
may refer instead to a field of the frame. In a more general sense, picture
refers to the entire image shown on a video display.
picture stop A function of DVD-Video where a code indicates that video
playback should stop and a still picture be displayed.
PIP Picture in picture. A feature of some televisions that shows another
channel or video source in a small window superimposed in a corner of
the screen.
pit A microscopic depression in the recording layer of a optical disc. Pits
are usually 1/4 of the laser wavelength in order to cause cancellation of
the beam by diffraction.
pit art A pattern of pits to be stamped onto a disc to provide visual art
rather than data. A cheaper alternative to a printed label.
pixel The smallest picture element of an image (one sample of each
color component). A single dot of the array of dots that make up a picture.
Sometimes abbreviated to pel. The resolution of a digital display
is typically specified in terms of pixels (width by height) and color
depth (the number of bits required to represent each pixel).
pixel aspect ratio The ratio of width to height of a single pixel. This
often means the sample pitch aspect ratio (when referring to sampled
digital video). Pixel aspect ratio for a given raster can be calculated as
y/x � w/h (where x and y are the raster horizontal pixel count and vertical
pixel count, and w and h are the display aspect ratio width and
height). Pixel aspect ratios are also confusingly calculated as x/y � w/h,
giving a height-to-width ratio. Refer to Table 6.22.
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