NTSC -- A television video format used in the United States and elsewhere. Displayed 525 lines of resolution at 60 fields per second, 30 frames per second (actually a fractional value near 29.97). Named for the National Television Standards Committee. See also PAL.
PAL -- Acronym for Phase Alternation Line. A television video format used in Europe and elsewhere. Displayed with 625 lines of resolution at 50 fields per second, 25 frames per second. See also NTSC.
NTSC safe colors -- Colors that are inside the safe region for NTSC television video. Title colors that are outside this range can display badly and bleed on NTSC televisions. See also safe area.
RF video -- Acronym for Radio Frequency. A composite video signal that has been modulated with audio onto a high-frequency radio wave that could be transmitted from an antenna. Typically connected to the antenna input of a TV receiver, and received on channel 3 or 4. The simplest and lowest-quality video signal connection. See also component video, composite video, DV, S-Video.
S-Video -- A video signal that transmits the brightness (luminance or luma) and the color (chrominance or chroma) information separately. Actually uses a single cable, but with two wires in the cable. Because the luma and chroma are separate, S-Video provides higher quality than composite video. Requires a separate audio signal and connector. Also called Y/C, or sometimes (incorrectly) called S-VHS. See also composite video, component video, DV, RF video.
F connector -- A video connector with a thin center wire typically used for antenna connections and RF signals. See also BNC connector, Firewire connector, RCA connector, RF video, S-Video connector.
RCA connector -- A connector with a single central plug, commonly used for audio signals and composite and component video. Also called a phono connector. See also BNC connector, F connector, FireWire connector, S-Video connector.
S-Video connector -- A specialized connector used for S-Video signals. Contains multiple pins for the separate video components. See also BNC connector, F connector, FireWire connector, RCA connector, S-Video.
BNC connector -- A twist-on connector commonly used for higher-end video systems. Used for both analog and digital signals. See also F connector, FireWire connector, RCA connector, S-Video connector.
Digital Video Fundamentals -
pixel -- The individual picture elements, or "dots" of color, that are arranged in a two-dimensional array to define a digital image or video frame. The dimensions or resolution of an image are described in terms of the horizontal and vertical pixel count.
resolution -- The dimensions of an image, in pixels, typically expressed as the number of horizontal pixels across and the number of vertical pixels down. See also aspect ratio.
transcode -- To convert from one compression format to another (that is, from DV video from a camcorder to MPEG-2 for DVD). Preferably done intelligently to minimize loss of quality from repeated compression, and not requiring fully decompressing the input and then recompressing to the output.
compress -- To reduce the size of audio or video data through the use of a compression scheme. Also called encode. See also decompress, lossy, and lossless.
decompress -- To process a compressed bitstream and recover the original data (if lossless compression), or an approximation of the original (if lossy compression). Also called decode. See also compress.
lossless -- Any compression scheme, especially for audio and video data, that uses a nondestructive method that retains all the original information, and therefore does not degrade sound or video quality.
lossy -- Any compression scheme, especially for audio and video data, that removes some of the original information in order to significantly reduce the size of the compressed data. Lossy image and audio compression schemes such as JPEG and MP3 try to eliminate information in subtle ways so that the change is barely perceptible, and sound or video quality is not seriously degraded.
perceptual compression -- A compression technique that takes advantage of knowledge of how humans perceive; that is, by eliminating visual detail that the eye cannot easily see or audio frequencies that the ear cannot easily hear.
compressor -- Program by which files are compressed. A compressor that also decompresses files (returns them to their original state) is called a codec. See also compress.
codec-- A video or audio compression component that can both compress and decompress (encode and decode) files. Media formats and players, such as Windows Media, RealMedia, and QuickTime have a selection of codecs built in, and can add additional codecs to support new file formats. See also compression.
Digital Video Formats -
DV -- A Digital Video tape and compression format for consumer and professional video equipment. The DV compression format is used for DV and Digital-8 camcorders. DV format video and audio can be captured using a FireWire / IEEE 1394 interface and then saved and edited in a video editor. The consumer tape format is more accurately called mini-DV. See also analog media.
FireWire -- A digital data interface standard that provides a high-speed Plug-and-Play interface for personal computers. Used for connecting DV camcorders to computers, as well as to hard disk drives and DVD drives. Supports up to 480 Mbps data rate. Also known as IEEE 1394 and Sony iLink. See also USB.
FireWire connector -- A roughly rectangular, hot-pluggable connector used for FireWire/IEEE 1394 digital connections, especially digital video signals such as from DV camcorders. The connectors can vary in size: full-size (6-pin) for connecting to a computer or hub, and smaller (4-pin) for connecting to equipment such as DV camcorders. See also BNC connector, DV, F connector, RCA connector, S-Video connector.
USB (Universal Serial Bus) -- A digital data interface standard providing a Plug-and-Play interface for personal computers. Typically used for lower-speed peripherals such as mice, keyboards, printers, and scanners. Also used for interfacing to digital cameras. The existing USB 1 standard provides up to 12Mbps (million bits per second) data rate. The new USB 2 standard supports up to 480Mbps data rate. See also FireWire.
AVI -- Acronym for Audio Video Interleave. The old multimedia file format used under Windows for interleaved video and audio streams. See also Video for Windows, Windows Media.
Video for Windows -- The media file format used with Microsoft Windows (.AVI). Supports many different video and audio compression formats (codecs). See also Windows Media.
Windows Media -- The multimedia platform built into Microsoft Windows, and a series of formats for storing and transmitting video and audio. Uses ASF, WMA, and WMF file types. See also Video for Windows, Windows Media Audio and Windows Media Video.
Windows Media Video (WMV) -- The Microsoft Windows Media format for compressed video and audio files on CD and DVD discs. See also Windows Media Audio.
QuickTime -- Multiplatform, multimedia Movie file format from Apple Computers (.MOV).
RealMedia -- Multiplatform, multimedia Web streaming file format from Real Networks (.RM, .RAM).
streaming media -- Internet video and/or audio clips that can play directly over the Internet, without needing to be downloaded first onto a computer. Used to view and hear broadcasts, and to interactively play and seek in stored clips. See also progressive download.
progressive download -- A technique for downloading Internet video and/or audio clips so that they can be viewed at the same time that they are being transferred to your computer. This provides some of the benefits of streaming media without requiring a special streaming server. See also streaming media.
MPEG -- A family of popular multimedia file formats and associated compression schemes defined by the Moving Pictures Expert Group. MPEG-1 video was designed for use on CD-ROMs and provides picture quality somewhat comparable to VHS. MPEG-2 video was designed for consumer video and is used on DVD, and can provide high-quality full-screen full-rate video with smaller file sizes. MPEG-4 video is designed for a broad range of multimedia applications, and is used for web and wireless streaming video. MP3 is a commonly-used audio compression format, especially for web downloads and portable music players.
MPEG-1 -- An older digital video compression format developed in the early 1990s by the Moving Picture Experts Group. MPEG-1 video was designed for lower-resolution video played from CD-ROM and provides picture quality somewhat comparable to VHS (typically 352x240 resolution). Used for Video CD discs.
MPEG-2 -- A TV-quality digital video compression format developed in the mid-1990s by the Moving Picture Experts Group. MPEG-2 video provides high-quality full-screen full-rate video (720x480 resolution for NTSC) with smaller file sizes than MPEG-1. Used for DVD discs, and also scales to high-definition resolution and bitrates.
MPEG-4 -- A digital multimedia compression format developed in the late 1990s by the Moving Picture Experts Group, that includes video, audio, and interactivity. MPEG-4 video is designed for interactive multimedia across networks, and works well for web and wireless streaming video.
CBR -- Acronym for Constant Bit Rate. A compression scheme in which each unit of input material is always compressed to the same output size. For MPEG-2 video, for example, this means that the compressed data always has the same data rate (that is, bytes per second), even when the input material is very easy to encode. See also VBR.
VBR -- Acronym for Variable Bit Rate. A compression scheme in which each unit of input material can be compressed to different sizes. For MPEG-2 video, for example, this means that "easier" sequences (that is, with no motion) can compress to very small sizes, whereas "hard" sequences (with lots of motion and scene cuts) can compress to much larger sizes. VBR compression can take better advantage of the overall available bandwidth of a video transmission or DVD player by allocating the available bits intelligently to the difficult parts of a sequence. See also CBR.
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