Glossary U-W

UDF Universal Disc Format. A ISO 9660-compatible file system that ensures that any file on a DVD can be accessed by any drive, computer or consumer video system, overcoming the incompatibility problems that CDs suffer from.
UDF/ISO (or UDF Bridge) A hybrid system that allowed Windows 95 machines to read DVDs; UDF support did not appear in the Windows operating system until the release of Windows 98.
UMD Universal Media Disc. A compact optical disc for use in Sony’s PlayStation Portable (PSP). It can hold 1.8 GB of data, including games, movies and music.
Unidirectional Prediction A compression method that uses information only from frames that have already been decompressed.
UOP User Operation Prohibitions. See PUO.
UPC (or EAN) Universal Product Code. A thirteen-digit catalog number which can be assigned to a disc during the recording process and written into the disc’s Table of Contents.
USB Universal Serial Bus. A universal method for connecting hardware to PCs; any device that is USB-compliant can just be plugged into the PC and turned on. The current version (USB 2.0) has a data transfer rate 40 times faster than its predecessor, USB 1.1.
User Data All data on a DVD above the channel layer, including video, audio, file management data, subpictures and navigation data.
User Interface A simple interactive menu providing access to disc programming content.
VBI Vertical Blanking Interval. Part of a TV signal which is left blank, allowing time for the electron gun to move from the bottom of the screen to the top as it scans images. These blank scan lines are now used for broadcasting closed-captioning and teletext signals.
VBR Variable Bit Rate. A bitrate that changes based on the amount of data being processed. A static image will have a low bit rate, while a scene with a lot of fast-moving action will have a high bit rate; VBR allows the bit rate to change as needed. See CBR (Constant Bit Rate).
VCD Video Compact Disc. An MPEG1-encoded video disc. The video quality is roughly equivalent to a VHS tape; this fact, combined with its small capacity (74–80 minutes) prevented this format from becoming widely accepted.
VCD Header Trick Changing the header file of an SVCD MPEG-2 video file into one for a VCD2.0 MPEG-1 file and then using it as a standard VCD2.0 file. The practical purpose of this trick is to be able to play an SVCD on a home DVD player.
Vdub VirtualDub. A Windows-based video capture/processing program, mainly aimed towards working with AVI files. It has batch-processing capabilities and can be expanded with third-party plug-ins.
VfW Video for Windows. A Windows-based video capture/display program, able to capture movies directly to disk. This program was renamed DirectShow in 1997, and is now part of the DirectX group of application program interfaces.
VHS Video Home System. An analog video format introduced into the mainstream in the early 1980s. It gained greater acceptance than rival Betamax among consumers in the spawning movie-rental industry, making it the winner of the infamous “format war” between the two (and coining the phrase that is still in use today). The VHS format, and VCRs in general, have been in decline with the rise of DVDs, but another format war is taking place between two next-generation technologies that will replace the DVD: Blu-Ray vs. HD DVD.
Video CD A standard for storing video and audio on a CD. Video and sound are compressed with MPEG 1 standard and recorded onto a CD Bridge disc.
Video Encoding Changing a video’s format by using a codec to alter its resolution and/or bitrate.
Video Manager The top-level menu on a disc that links multiple tiles from a common point.
Video_TS The UDF filename for the video directory on a disc volume. Files under this directory name have pointers to the program stream sectors on the disc.
VLC VideoLAN Client. A multimedia player that can handle a large number of audio and video formats, including MPEG-1, MPEG-2, MPEG-4 DivX, mp3, ogg, DVD and VCD. It can also be used as a server for IPv4 and IPv6 streaming broadcasts.
VMGI (or VMI) Video Manager Information. Acts as a pointer to the titles in a disc volume, and identifies both disc side and content type.
VOB Video Object. One of the core files on a DVD that contains the actual movie data. Essentially, a VOB file is an MPEG-2 system stream, a file that contains multiplexed MPEG-2 video stream, audio streams and subtitle streams.
  1. A single CD-ROM disc.
  2. A session on a multisession disc that is not linked to other sessions.
Volume Descriptors An optional set of information fields recorded at the start of the data area on a disc. They include:

  • System Name
  • Volume Name
  • Volume Set Name
  • Publisher’s Name
  • Data Preparer’s Name
  • Application Name
  • Copyright File Name
  • Abstract File Name
  • Bibliographic File Name
  • Date Fields
Volume Space A collection of sectors that make up a volume, including those sectors used for leaders.
VTS Video Tile Set. A set of files (10 maximum), preceded by a management file, with each file limited to 1 GB in size.
VTSI Video Tile Set Information. Describes the nature of a video tile set (VTS).
Warez Illegally distributed intellectual property, such as software, movies or music. Special forms of warez are software serial numbers (serialz) and methods for breaking software security (crackz).
WAV A common audio file format for Windows. WAV files are generally uncompressed and not processed, making them “raw” audio samples.
Widescreen A video image with a wider aspect ratio than the 4:3 TV standard. In DVD or HDTV, “widescreen” usually means a 16:9 ratio.
WinDVD A DVD playback software for the PC.
WMA Windows Media Audio. A compressed audio file format developed by Microsoft, supported by nearly as many hardware and software platforms as MP3. WMA files are often part of Advanced System Format (ASF) files; the file extensions for a WMA file might therefore be .wma or .asf. The format uses cryptography and key exchanges to facilitate digital rights management.
WMF Windows Media Format. Audio or video files encoded with Windows Media Encoder. The result of the encoding is a high-quality, secure media file for streaming or downloading.
WMP Windows Media Player. A multimedia player that can handle a large number of formats in their original forms (WAV, ASF, WMF and MPEG-1) and can also play other types of files when the proper third-party codecs are downloaded and installed (AVI and MPEG-2).
WMV Windows Media Video. The companion program to WMA, but for video and/or audio (instead of just audio). WMV files can be streamed through a network or downloaded for playback.
WMV HD Windows Media Video High-Definition. The successor to WMV, with a much higher resolution (either 1280 × 720 [720p] or 1920 × 1080 [1080p]).

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