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Glossary:
OD - Push/Pull
Glossary of CD and DVD related
technical terms and abbreviations in alphabetical order. |
O
OD: Outside Diameter, eg of a CD or the print area of a CD.
Opposite Track Path: Layer 1 of a DVD-9, where the data starts above the
end of data on Layer 0 and ends at or near the ID of the disc. The
Program Area on this type of layer is preceded by the Middle Area.
Orange Book: Specification from Philips & Sony defining
CD-Recordable discs (CD-R/CD-RW/CD-MO).
OSTA: Optical Storage Technology Association, an international trade
association dedicated to promoting use of writable optical technology
for storing computer data and images. OSTA has over 60 Members and
Associates in North America, Asia, and Europe. It also promotes UDF.
P
P-channel: one of the CD subcode channels. The P-channel is used to
indicate the gap between tracks on a CD.
P-Frame: Predictive frame of an MPEG sequence.
Packet Writing: A method of writing CD-ROM data to a CD-R in smaller
increments than a session.
PAL: Phase Alternation Line. Video format used in most of Western
Europe, Australia and other countries
Pan & Scan: A method for displaying wide screen video on a
conventional TV by showing only part of the full width. The part shown
is normally adjusted during the video depending on where the most
important action is.
Parallel Track Path: Layer 1 of a DVD-9, where the data starts at the ID
of the disc and ends near the OD.
Parental Lock: A means to prevent certain scenes on a DVD-Video disc
from being seen by children.
PCA: Power Calibration Area, which is located at the beginning of a
CD-R, for calibrating the laser power needed for writing.
PCM: Pulse Code Modulation, the most common method of encoding an
analogue audio signal into a digital bit stream.
PGC: Program Chain, containing instructions in a DVD-Video title for
controlling interactivity and the presentation of AV sequences and
menus.
Phase-Change: The technology used for CD-RW, DVD-RAM and DVD-RW discs,
whereby the phase-change material can be in either of two phases:
amorphous and crystalline. One phase represents a 0 at that point, the
other a 1. A laser is used to change the phase of the active material
where required.
Photo CD: CD format defined by Kodak and Philips for storing photographs
for display and/or subsequent printing.
Photo Resist: A light-sensitive coating (eg on a glass master). After
exposing to light (eg using a laser) it can be developed so that the
exposed areas are removed.
Picture Disc: A CD or DVD which has been printed using 5 colours,
a white base colour plus four colour separations: Cyan, Magenta, Yellow
and Black (CMYK). A sixth 'spot' colour can be added for special
effects.
Pit Art: A method for adding labels to DVD discs by creating a
hologram-like image in the blank substrate of a DVD-5 in place of pits
that would be present on a DVD-9 or DVD-10 disc.
Pits: The hollows in a compact disc or DVD surface defining the data
they contain. Pits measure less than 0.5 microns in width and are
created by injection moulding using a nickel stamper.
Pixels: An abbreviation for picture element. The minimum raster display
element, represented as a point with a specified colour or intensity
level.
Plug & play: A term used eg in computers where software or hardware
will play automatically eg when a CD-ROM disc is loaded or when a device
is connected to a computer via a USB port. This feature is common in CD
audio and DVD-Video players, but has not always been available on
computers.
PMMA: PolyMethylMethAcrylate (also known as Acrylic), a thermo-plastic
material considered for CDs but is rather brittle and the Aluminium
layer does not adhere well to its surface.
Polycarbonate: A thermo-plastic material that is used to mould CD and
DVD discs. It can be injection moulded and has the necessary mechanical
and optical properties.
Post-Gap: The area on a CD or CD-ROM comprising 150 sectors at the end
of the track before one of a different type (ie at the end of a CD-ROM
track followed by a CD-Audio track). PPCM:
Packed PCM, otherwise known as MLP, a method of losslessly
compressing audio files on a DVD-Audio disc.
PQ-Encoding: An audio CD pre-mastering process needed to add tracks to a
CD.
Pre-mastering: Process to convert the data representing audio or a
CD-ROM application into the data to be stored on the CD. For PC CD-ROMs
it will involve adding the ISO 9660 file structure data. Also refers to
creating a disc image for a DVD-Video, DVD-Audio or DVD-ROM title, where
the file system is Micro UDF.
Prediction: The use of a predictor to provide an estimate of the data
element currently being decoded, eg for ADPCM audio encoding. Both ADPCM
and MLP use prediction for subsequent samples and then code only the
difference between the predicted and actual values.
Primary Volume Descriptor: The PVD is located at sector 16 of a CD-ROM
data session and contains the file system information.
Program Area: The largest area on a CD or DVD disc containing the data
representing audio, video etc. On a multisession CD there will be one
program area per session.
Progressive scan: A method of scanning a TV display where all
lines in a frame are displayed in sequence from top to bottom. This is
the alternative to interlaced scan and also involves an increase in
frame rate from 25 Hz to 50 Hz or 30 Hz to 60 Hz to avoid flicker.
PSP: Pit Signal Processing, used for invisible watermarking on a DVD or
CD disc to prevent copying. PSP is specified for SACD discs.
Pulldown: A technique (3/2 pulldown) for converting 24 fps film to 30
fps NTSC video by adding fields.
Purple Book: Specification from Philips & Sony for Double Density CD
(DDCD) read-only, recordable and re-writable versions of the CD with
capacity of 1.3GB.
Push/Pull: The tracking signal when the pickup laser in a CD or DVD
player crosses pits in a radial direction.
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