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4:3
Traditional nearly square aspect ratio used for most current analog television screens and IMAX movie theater screens. This aspect ratio will slowly be phased out in favor of the wider, more panoramic and movie-like 16:9 ratio. Video displays using a 4-by-3 ratio display images 4 units wide (horizontal measure) by 3 units tall (vertical measure).
5.1 Audio
In contrast to the Stereo sound system and conventional Surround Systems, this sound system offers five separate full band audio signals: Left, middle, right, rear left, rear right. An additional subwoofer (LFE) channel is also provided.
AC3
See Dolby Digital. A .ac3 file is a Dolby Digital audio file.
AIFF
Macintosh AIFF Resource ( .aif, .aifc, .aiff) Audio Interchange File Format (AIFF) is an audio file format that was developed by Apple Computer. This format may be used to store high-quality sampled audio and musical instrument information.
Aliasing
A distortion (artifact) in the reproduction of digital audio or video that results when the signal frequency is more than twice the sampling frequency. The resolution is insufficient to distinguish between alternate reconstructions of the waveform, thus admitting additional noise that was not present in the original signal.
Anamorphic
Process where a “wide” video image (typically in a 16:9 widescreen format) is compressed or squeezed horizontally to fit a more narrow video display standard but expands to full size when played over a wide video display.
Antialiasing
Smoothing or reducing disturbing picture effects. By means of calculation of intermediate values along the sharp edges of types and graphics, these edges can be smoothed out, thus generating a smoother picture. The pixel structure along tilted or bent edges is mixed with the surrounding colors. When creating DVD Menu text, antialiasing must not be used.
Artifact
An unnatural effect not present in the original video or audio, produced by an external agent or action. Artifacts can be caused by many factors, including digital compression, film-to-video transfer, transmission errors, data readout errors, electrical interference, analog signal noise, and analog signal crosstalk. Most artifacts attributed to the digital compression of DVD are in fact from other sources. Digital compression artifacts will always occur in the same place and in the same way. Possible MPEG artifacts are mosquitoes, blocking, and video noise.
Aspect Ratio
The width-to-height ratio of an image. A 4:3 aspect ratio means the horizontal size is a third again wider than the vertical size. Standard television ratio is 4:3 (or 1.33:1). Widescreen DVD and HTDV aspect ratio is 16:9 (or 1.78:1). Common film aspect ratios are 1.85:1 and 2.35:1. Aspect ratios normalized to a height of 1 are often abbreviated by leaving off the :1.
Bitrate
Bitrate or Bit Rate is the average number of bits that one second of video or audio data will consume. Higher bitrate means bigger file size and generally better video or audio quality while lower bitrate means lower file size but worse video or audio quality. Some bitrate examples in common video and audio files:
MP3 about 128 kbps (kilobits per second)
VCD about 1374 kbps
DVD about 4500 kbps
DV about 25 Mbps (megabits per second).
Capture
Also called Cap or Capping - To capture video or TV/Sattelite signals to disk. This can include firewire capture from DV cameras.
Chroma Key
The Chroma Key process is based on the Luminance key. In a luminance key, everything in the image over (or under) a set brightness level is "keyed"out and replaced by either another image, or a color from a color generator. Also known as Blue Screen Compositing, the
Chroma Key Process was made famous by films such as star wars where spacecraft miniatures were composited onto starfield backgrounds.
CO-DEC
a COmpression-DECompression algorithm used for efficient storage and transmission of a data file, such as a video or audio file.
Compression
The process of removing redundancies in digital data to reduce the amount that must be stored or transmitted. Lossless compression removes only enough redundancy so that the original data can be recreated exactly as it was. Lossy compression sacrifices additional data to achieve greater compression.
Convert
To change from one form into another. In video obviously it is to change one form of video into another. For example, many people like to convert divx to MPEG, quicktime to AVI , etc. Conversions to a final format is called encoding - an example is AVI to VCD MPEG-1.
Crop
To cut away pieces of a video stream without rendering; similiar to cutting a picture with scissors.
Deinterlace
The process of creating a single frame from the 2 interlaced fields of a video frame. Deinterlacing is used to remove the interlacing artifacts if a still frame is required, or if the video is being used at a different rate than it was created.
Dolby Digital
Dolby's best-known digital system, is used to provide multichannel surround sound in cinemas from 35 mm film, and in the home from laser discs, DVDs, and digital broadcast television, cable, and satellite systems. It enables the transmission and storage of up to five full-range audio channels, plus a low-frequency effects channel (LFE), in less space than is required for just one linear PCM-coded channel on a compact disc.
Encoding
Encoding is the process of changing data from one form into another according to a set of rules specifiec by a codec. The data is usually a file containing audio, video or still image. Often the encoding is done to make a file compatible with specific hardware (such as a DVD Player) or to compress or reduce the space the data occupies.
Firewire
FireWire is a fast peripheral interconnect standard capable of transfer speeds up to 400 Mbs. It works well for multimedia peripherals such as DV (Digital Video) cameras and other high-speed devices like the latest hard disk drives, CD/DVD burners and printers.
.flv (Flash Video File)
A file format used to deliver video over the Internet to the Adobe Flash Player Flash Video is viewable on most operating systems, via the Macromedia flash player or one of several third-party programs such as Media Player Classic (With the ffdshow codec installed), MPlayer, VLC media player (since version 0.8.4a), and FLV Player.
Garbage In Garbage Out
Garbage In, Garbage Out or sometimes called Crap In, Crap Out is a computer term describing the fact that the output data is only as good as the input data. It means basicly the same as a video term, the output video and audio quality can only be as good as the source video and audio quality.
MPEG
The Moving Picture Experts Group defines industry standards for the encoding, management, and delivery of content through various media.
MPEG-1
A codec designed for near-VHS quality video. MPEG-1 is primarily designed for CD-ROM delivery of content through various media.
MPEG-2
A codec designed for high-quality video. MPEG-2 is primarily used for DVD disc encoding and other high-quality archival solutions, but can be streamed over high-bandwidth connections, such as Internet2. MPEG-2 playback often requires additional software and/or hardware.
MP3
A codec designed for audio. MP3 is the most popular standard used for distribution on the Internet and in portable music players, such as Apple’s iPod. Note that MP3 stands for MPEG Audio Layer 3, not MPEG-3 (there is no MPEG-3). MP3 is an acronym for MPEG-1 (or MPEG-2) Layer 3 audio encoding (it is not an acronym for MPEG3). MP3 is a popular compression format used for audio files on computers and portable devices.
MPEG-4
Built around non-proprietary codecs, MPEG-4 excels at multi-architecture compatibility. Future codecs should enhance quality.
Mini DV
Mini DV is a video cassette designed for use in MiniDV digital camcorders. The picture quality of digital video (DV) recorded on a Mini DV cassette is basically identical or better to the quality of DV recorded on a Hi8 or 8mm cassette by a Digital8 camcorder. Mini DV can have up to 530 lines of video resolution for some camcorder models. However, Mini DV tapes are smaller which allows for smaller camcorders. Mini DV tapes are available in lengths of 30 and 60 minutes (plus, recording in LP mode lets you extend total recording time with a 60-minute tape to 90 minutes).
MOV
QuickTime Content (.mov, .qt) - a file format developed by Apple Computer to create, edit, publish, and view multimedia files. QuickTime supports video, animation, graphics, 3D and virtual reality (VR).
NTSC
Abbreviation of National Television Standards Committee. The NTSC is responsible for setting television and video standards in the United States (in Europe and other parts of the world, the dominant television standards are PAL and SECAM). The NTSC standard for television defines a composite video signal with a refresh rate of 60 fields (half-frames interlaced) per second. Each frame contains 525 lines and can contain 16 million different colors. The resolution of an NTSC VCD is 352x240 pixels, an NTSC SVCD is 480x480, and an NTSC full D1 DVD is 704 or 720 x 480.
PAL
Short for Phase Alternating Line, the dominant television standard in Europe. The United States uses a different standard, NTSC. PAL delivers 625 lines at 50 fields (half-frames interlaced) per second. The resolution of a PAL VCD s 352x288 pixels, a PAL SVCDis 480x576, and a PAL full D1 DVD is 704 or 720 x 576.
PIP
Picture in picture. A feature of some televisions that shows another channel or video source in a small window superimposed in a corner of the screen.
Pixel
The smallest picture element of an image (one sample of each color component). A single dot of the array of dots that makes up a picture. Sometimes abbreviated to pel. The resolution of a digital display is typically specified in terms of pixels (width by height) and color depth (the number of bits required to represent each pixel).
Pixel Aspect Ratio
The ratio of width to height of a single pixel. Often means sample pitch aspect ratio (when referring to sampled digital video). Pixel aspect ratio for a given raster can be calculated as y/x multiplied by w/h (where x and y are the raster horizontal pixel count and vertical pixel count, and w and h are the display aspect ratio width and height). Pixel aspect ratios are also confusingly calculated as x/y multiplied by w/h, giving a height-to-width ratio.
Real
Built around proprietary RealNetworks codecs, Real format excels at low to medium bandwidth clips. It supports MPEG-4. Producers can use the SMIL language to add interactivity.
QuickTime
A digital video software standard developed by Apple Computer for Macintosh (Mac OS) and Windows operating systems.
Built around several non-proprietary codecs, QuickTime excels at medium to high bandwidth clips. It supports MPEG-4.
Quicktime Player can be used to view numerous types of video and audio files.
Sample Rate
The number of times a digital sample is taken, measured in samples per second, or Hertz. The more often samples are taken, the better a digital signal can represent the original analog signal. Sampling theory states that the sampling frequency must be more than twice the signal frequency in order to reproduce the signal without aliasing. DVD PCM audio allows sampling rates of 48 and 96 kHz.
SWF
A proprietary vector graphics file format produced by the Adobe Flash software. Intended to be small enough for publication on the web, SWF files can contain animations or applets of varying degrees of interactivity and function. The Flash program produces SWF as the compressed and uneditable final product, whereas it uses the .fla format for its editable working files.
Time Code
Information recorded with audio or video to indicate a position in time. Usually consists of values for hours, minutes, seconds, and frames. Also called SMPTE time code. Some DVD-Video material includes information to allow the player to search to a specific time code position.
Transcoding
On this site generally another name for encoding.
A more technical term would be "The reformatting of content, without changing the source, to another type of content - most often of a different format than the original (but does not have to be)"
Video Encoding
The process for changing a video from one format to another by altering the resolution and/or the bitrate. Normally the result of this process is a movie with a different compression. For a proper encoding you need a piece of software and/or hardware, which is called codec.
WAV
WAV files are probably the simplest of the common formats for storing audio samples. Unlike MPEG audio and other compressed formats, WAVs store samples "in the raw" where no pre-processing is required other that formatting of the data.
WMA
Windows Media Audio.
WMV
Windows Media file with Audio and/or Video (WMV): You can use a .wmv file either to download and play files or to stream content. The .wmv file format is similar to the .asf file format.
Windows Media
built around proprietary Microsoft codecs, Windows Media excels at medium bandwidth clips. It does not support MPEG-4.
