Glossary O-Q

O
OEM Original Equipment Manufacturer. An OEM purchases hardware in bulk and, after customizing it for a particular application, resells it under their own brand name.
Ogg Theora The video compression codec from the OGG open-source multimedia project.
Ogg Vorbis An open-source audio compression format. Ogg is the name of xiph.org’s container format for audio, video and metadata. Vorbis is an audio compression scheme contained in Ogg (other formats are capable of being embedded in Ogg such as FLAC and Speex).
OGM Ogg Media. A video and audio container similar to AVI or Matroska.
On the Fly To write directly to disc without first creating a disc image.
Open GOP A GOP that references images from a prior GOP. See GOP.
Opposite Track On a dual-layer disc, the tracks on layer 0 and layer 1 run in opposite directions—layer 0 reads from the inside edge of the disc to the outside, and layer 1 reads from the outside to the inside. This allows a seamless transition from layer 0 to layer 1 during playback; the laser does not have to go all the way back to the inside edge to continue playing.
Optical Output The connection between a DVD player’s digital output to a surround sound processor to process DVD (Dolby Digital) sound.
Optimum Power Calibration Area An area near the center of a recordable disc, reserved for the purpose of calibrating the power level of the writing laser.
Orange Book The recording standard for recordable CDs.
Outer Diameter The width of a disc. Regular CDs and DVDs have an outer diameter of 12 centimeters; small discs have an outer diameter of 8 centimeters.
Overburn Writing beyond the “security zone” edge of a recordable disc in order to fit more data on it.
Overscan The area at the edges of a television tube that is covered to hide possible video distortion. Overscan typically covers about 4 or 5 percent of the picture.
P
Pack A collection of MPEG stream packets. On a DVD, one pack is coded on each disc sector.
Packet 2,048 bytes from a single stream aligned to a DVD sector.
Packet Writing Writing data on a disc in small increments instead of all at once.
PAL Phase Alteration by Line. The broadcasting standard for most of Europe, Asia, Australia and parts of Central/South America. It consists of 625 lines of resolution, broadcasting at 25 frames (50 interlaced fields) per second.
Palette A table of color values.
Pan & Scan Reframing a 16:9 video to 4:3 by selectively cropping the left and right sides of the image. This can be done as an editing step, or automatically by some DVD players.
Panavision Using anamorphic lenses to shoot a widescreen aspect ratio (2.35:1) on 35mm film.
Parallel Track A dual-layer disc where the tracks on layer 0 and layer 1 both run in the same direction. See opposite track.
Parental Locks (or Parental Controls) A feature of TVs and DVD players that allows parents to block programs based on their rating (Parental Guideline Ratings System for TV shows, MPAA ratings for movies). Some DVDs can automatically skip over parts of movies based on how the parental controls are set.
Part Subset of a DVD Title. Like Chapters on a video laserdisc, Parts are useful tools for designating a collection of video objects belonging to a common scene.
PBC Playback Control. Available for VCD and SVCD, it allows limited interaction (via menus) between a viewer and a program.
PCA Power Calibration Area. See optimum power calibration area.
P-CAV Partial-Constant Angular Velocity. A type of disc-recording drive that reaches its maximum transfer rate very quickly and then maintains that speed for the remainder of the recording session.
PCI Presentation Control Information. Information about the timing and presentation of a program.
PCM Pulse Code Modulation. Standard format for CD/DVD audio, PCM is an uncompressed digital representation of an analog signal.
PCMCIA Personal Computer Memory Card International Association. An organization of more than 500 companies that develops PC Card (memory card) standards.
Perceptual Coding A lossy audio compression technique used by Dolby Digital which relies on the limits of human perception—signals beyond the range of human hearing are dropped.
P Frame In the MPEG-2 compression process, a P Frame is made by analyzing previous frames and estimating where objects will be in the next frame. See B Frame and I Frame.
PGCI Program Chain Information. Describes the physical sector locations of each program in a program chain.
Photo CD Kodak’s proprietary CD format for storing, displaying and printing photographic images.
PhotoVCD A group of image files stored on a VCD and then displayed in a slideshow format.
Physical Format (or Low-Level Format) The division of hard disk platters into tracks, sectors, and cylinders. Physical formats are defined by the “color book” standards (e.g., Red Book, Yellow Book, Orange Book, etc.).
Physical Sector Number A serial number assigned to a physical sector on a disc.
PIP Picture-in-picture. A feature of some TV sets that allows another channel or video source to be viewed in a small window that is superimposed on the main screen.
Pit A microscopic depression on the recording layer of a disc.
Pit Art Labeling a DVD by cutting the pits to create words or images.
Pit Length The arc length of a pit along the direction of the track.
Pits and Lands The surface of a disc has pits and flat surfaces (lands) that are read by a laser beam and translated into a binary stream which is decoded for playback.
Pixel The smallest independent unit of a digital image. The resolution of a digital image is defined by the number of pixels used to create the image and the number of bits used to represent each pixel (color depth).
Pixel Aspect Ratio The ratio of width to height of a single pixel.
Pixel Color Depth The number of bits of color information in a pixel. Eight bits per pixel can display 28 = 256 colors, while 24 bits per pixel can display 224 = 16,777,216 colors. Twenty-four bit color is sometimes called “true color” because it exceeds the number of colors actually perceptible to the human eye (about six million).
PMA Program Memory Area. The space on a recordable disc where the Table of Contents is temporarily written until a session closes (at which point the Table of Contents is written into the session lead-in).
POP Picture Outside Picture. A feature of some widescreen displays that shows pictures in the unused area around a 4:3 video.
Portable DVD Player A small, lightweight DVD player with its own built-in screen. A user can either view DVDs on this screen or hook it up to a full-size TV.
PowerDVD DVD player software for Windows.
Premastering Preparing data in its final format before creating a DVD disc image for mastering. Premastering steps can include:

  • Creating DVD control/navigation data
  • Multiplexing data streams
  • Generating error-correction codes
  • Performing channel modulation
  • Encoding video, audio, and subpictures
Presentation Data Information which is presented at a specified time, such as video or audio samples.
Production Notes Information about a movie’s production, cast and crew included on a DVD.
Program Stream A combination of audio and video streams sharing a common time base.
Progressive Scan A video scanning system that displays all lines of a frame in one pass instead of interlacing them.
Pro-Logic (or Dolby Surround) A small amount of data encoded into a stereo audio stream that can be recognized by a decoder so that the decoder can separate the stereo signal into four or five channels.
PTT Menu (or Chapter Menu) A DVD menu that can access a particular Part of Title (PTT) in a Video Title Set (VTS).
Pulldown Duplicating and splitting film frames in order to change its frames-per-second speed when transferring from film to video.
PUO Prohibited User Operation. Instructions written into a DVD which disallow buttons from functioning. For instance, during the FBI Anti-Piracy warning on commercial discs, a PUO prevents it from being skipped by pressing menu or FF buttons.
Q
QSIF Quarter-SIF. A compressed video format: NTSC = 176 × 112 resolution, 29.97 fps; PAL = 176 × 144 resolution, 25 fps. The low data rates make QSIF ideal for Internet applications.
QT Mutator An older Mac program that synchronized QuickTime movies by altering their frame rate. Nowadays, programs create in-sync video files automatically.
Quantisation A process performed on a video signal to remove subjective redundancy and control the compression factor.
Quantize Matrix Quantization matrices are used by MPEG compressors to decide how accurately the frequencies present in the image need to be represented. Typically, lower frequencies should use lower quantization, and thus higher accuracy.
QuickTime (File extension: .qt) A digital video software standard for both Mac and Windows PCs, developed by Apple. The player software (QuickTime Player) can display numerous types of video and audio files.

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