Glossary - A Practical Guide to Video and Audio Compression - page 735

Topic Description

Object A fragment of data that is self-contained within a package. The

object has properties that can be examined or changed and
methods that can be executed procedurally.

Object oriented A technique of encapsulating data with descriptions of the

functional behavior so that systems can be constructed with a
set of component parts. The internal implementation of an object
is private and hidden. Only the published API is visible. This
leads to significant reuse of the same coding.

Ogg-Vorbis An open-source alternative to the other codecs for audio

compression.

OLED Organic Light-Emitting Diodes. A new technology for creating

displays that can be “printed” onto a plastic substrate. This
allows very flexible and cheap displays to be manufactured.

Overcranked Moving pictures that were shot at a slower speed than that used

to project or view them.

Package A container for multimedia. Commonly stored as a file.

Packet A fragment of data that is transmitted on a network. The packet

transfer is acknowledged or requested again in resilient systems.
The process of creating packets is informally called packetizing.

PAL Phase Alternate Line. This is the format used in the UK and

elsewhere in place of the NTSC transmission format used in the
USA. The name describes the way that the color information is
coded with a phase reversal of the information on each alternate
line. For compression purposes we wouldn't be concerned with
that phase reversal, as the capture card would have used it to
decode the color information. However, we do need to ensure
that we correctly choose PAL or NTSC according to the material
being captured, as the two systems are incompatible.

PDA Personal digital assistants are small, handheld devices that have

a touch-sensitive display for interacting with.

P-frame A predictive frame.

Pixel A single picture element. This describes the color and

transparency at a single unique Cartesian coordinate within an
image plane.

Pixlet This is a special codec developed by Apple for Pixar. Pixlet is

specifically designed to deliver high-quality, frame-accurate
video around a corporate network. Each frame is compressed as
a single block, thus eliminating artifacts caused by macroblock-
based compression algorithms. The picture is coded with a

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