Glossary of terms

If there is a term that you think should be included in this glossary, please suggest it in the Video help forums.

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3:2 Pulldown - See Pulldown

Anamorphic - Widescreen footage that has been scaled to cover the 4:3 resolution of a DVD. It looks stretched. (more..)

ASF - Advanced Streaming Format. A video container by Microsoft designed for streaming and used to contain audio and video encoded using Windows Media codecs. (More)

Aspect Ratio - The ratio (proportion) of width to height of video footage. Television is 4:3. (more..)

ASPI - Advanced SCSI Programming Interface, a method that some programs use to access data on drives. Although designed for SCSI drives, it is actually required for non-SCSI devices too, so Force ASPI is sometimes required. Useful for accurate DVD and CD ripping.

AVI - Audio Video Interleave, a filetype which is the basic container in windows for Audio and Video and is used for containing all kinds of compressed and uncompressed video. AVI is not a codec as there can be numerous different codecs you could use in an avi file.

AVISynth - A virtual frameserving tool designed for processing video information in windows. (More)

Bitrate - the amount of Bits allowed to be used for compressing audio or video every second. This facilitates as a quality control in most cases.

Bits - BInary Digits (more..)

Brightness - In RGB terms this is the sum of all colour values.

CBR ABR and VBR - Constant Bitrate, Average Bitrate and Variable Bitrate. Constant is pretty self explanatory, Average makes sure that the bitrate fluctuates around a certain value and Variable allows the bitrate to be set as low or as high as the encoder dictates. (More)

Chroma - Chromacity. This property of colour tells us how 'pure' a hue is (see below for hue). That means there is no white, black, or gray present in a colour that has high chroma - i.e. the colour will appear very vivid (see saturation) (more..)

Codec - Compressor/Decompressor.. system of converting audio and video from a compressed form into real data and back again (more..)

Colourspace - (see this guide)

Compressibility - A video or audio's ability to be compressed. High compressibility is a good thing.

Compression - the process of making something (i.e. video or audio data) smaller than its source - can be lossy or lossless.

Contrast - A term used to describe the degree of white to black)variation in an image. In a black and white image, there is a large difference in the value range (since there are no in-between grays in the image). An image made of only black and white (and no gray values) is therefore the highest in contrast, while an image with many grays and few white (highlights) and black (shadows) is a low contrast image.

Cropping - Removing the edges of something, usually video.

Demux - See Mux

DirectShow - What Windows mainly uses for playback of audio and video. Most video codecs have both a Video for Windows layer and a DirectShow layer which is dedicated to playback.

DivX - (See codec guide)

Dot Crawl - Dot crawl affects the edges of colour and manifests itself as moving dots of colour along these edges. It is an inherent flaw in both the PAL and NTSC video systems and cannot be eliminated fully once it has been introduced into the video stream. It is mainly an artifact of composite video processing but is also present on some digital sources. Can be slightly overcome in anime by using warpsharp. (More)

Drop-Frame Timecode - A type of timecode designed to make the count of frames correspond to the actual time. NTSC framerate is 29.97 frames per second, not 30, so that over a 60 minute period a timecode reader would count 108 frames (3.6 seconds) short. To correct this situation, at the beginning of each minute frames 0 and 1 are "dropped" so that the frame count starts at 2. This would result in 120 frames added in an hour, 12 more than needed. By negating this correction at the beginning of every 10th minute, time code is forced to agree with clock time. In english, it lets you edit at 29.97fps :). (More)

Dual Channel Stereo - Sets an audio encoder so that, during every second of stereo, instead of having the bitrate be distributed between left and right channels as the encoder likes, this setting forces each channel to have exactly half the designated bitrate (so if it was 128kbps each channel would have 64kbps). This is generally not a good thing in my opinion :)

DV - see editing codecs

DVDs - Digital Versatile Discs... you really should know what these are by now :)

DVD2AVI - Strangely enough this program is NOT used for creating AVI files. Its primary use is to scan through a DVD stream and create a project file that indexes the stream for faster access for interpretation as video data by an external application such as AVIsynth with mpeg2dec or TMPGenc.

ErMaC - a drastic ginger-haired mouse that is known to be a demon at DDR.

Field order - The order in which a field is displayed during playback. This is either Top (odd) Field First or Bottom (even) Field First. (More)

Fields - One field is every other line in a full video frame. Fields are designed to take advantage of the 2-pass display method of televisions. (More)

Film - Non-interlaced, full frame footage. Originally 24fps but 23.976 if adapted for use in NTSC. (More)

Filter - a program or algorithm designed to manipulate an input audio or video data to produced an altered output e.g. A "grayscale" filter changes a colour input into shades of gray.

FourCC - Four Character Code. Four letters that tell Windows which codec the video stream contained in an AVI file is encoded with (e.g. DIV5, HFYU, XVID etc.)

FPS - Frames Per Second. The amount of still frames that are displayed during one second of video. NTSC standard is 29.97, PAL and SECAM are 25, FILM is 24 or 23.976. (More)

Frame - Either one image in a video stream or one section of an audio stream.

Framerate - see FPS

Frameserver - a program that generates a frame for another program on request instead of writing all the frames to one file beforehand.

GUI - Graphical User Interface for making software user-friendly

Hue - This is what we usually mean when we ask "what colour is that?" For example, when we talk about colours that are red, yellow, green, and blue, we are talking about hue. Different hues are caused by different wavelengths of light so changing a hue will be changing its colour but not its saturation or lightness.

HuffYUV - A video codec that compresses video data using Huffman encoding to retain every bit of data (i.e. lossless compression) (more..)

Inter-Frame Compression (see this guide)

Interlaced - An attribute of video (especially NTSC video) where frames have been weaved together in order to take advantage of the display methods of televisions. (More)

Interleave - This is usually a value that describes the way in which audio is linked to video footage - e.g. every frame, every second etc... (more..)

Intra-Frame Compression (see this guide)

I-Frames, P-Frames and B-Frames (see this guide)

Inverse Telecine - The process of reversing 3:2 pulldown so to restore the original FILM frames of your footage (more..)

Joint Stereo - A method that takes advantage of the similarities between the left and right channels in an audio file so that it requires less data to compress it. (cp. dual channel) (more..)

Lossless - Not losing any data/information.

Lossy - Losing data, usually in a compression or conversion of some kind. (cp. lossless)

Luma - The luminance or lightness is the measurement of the intensity of light in a colour. Corresponds to the Y value in YUV colourspace. (More)

Masking (audio) - Phenomenon where certain audio elements cannot be heard when played alongside or following other audio elements. (More)

MJPEG - Motion JPEG, an adaptation of the Joint Pictures Expert Group system for compressing images for implementation as a video codec. (More)

MPEG - Motion Picture Experts Group, a committee that develops audio and video standards including MPEG1 used for vcds, MPEG2 used for DVDs and MPEG4 used for DivX and similar codecs. (More)

Mux - Multiplexing. This is process of combining separate audio and video streams together to make one file. The act of separating these streams is called Demuxing or Demultiplexing. You can do this with MPEG 1 or 2 streams using MPEG Tools in TMPGenc.

Nandub - An adaptation of VIrtualdub designed for precise manipulation of the DivX3.11a video codec. Developed by Nando, see also SBC.

Normalisation - the process of increasing the volume of an audio source until the loudest part has reached the maximum volume that can be stored. (More)

NTSC - System of video transmission used in the USA and Japan (more..)

Overscan - The border area (around 10%) of video that is cropped by televisions (more..)

PAL - System of video transmission used in Europe and many other countries internationally (more..)

Pan and Scan - A procedure where a 4:3 image is taken from a widescreen source by clipping the edges. (More)

Pixels - A Picture Element - the smallest element you can see on a monitor or television display. The more pixels an image contains, the higher its resolution.

Premiere - Video editing software packed created by Adobe Systems (more..)

Progressive - Non-interlace full-frame footage or display device, so-called because a progressive image is displayed in one fast sweep, unlike interlaced images which are displayed in two passes, each pass displaying every other line. (More)

Psychoacoustics - The theory of how the brain interprets audio. (More)

Pulldown - This is the process of making multiple fields from frames in order to change the framerate of a source. Film footage is converted from 24fps to 30fps by creating 3 Fields out of the 2 fields usually contained in a single frame (i.e. 3:2 pulldown). PAL footage uses 2:2 pulldown where 2 fields are kept as 2 fields. (More)

Quicktime. Software developed by Apple for the compression/decompression of video. Contains various codecs including Sorenson and recently Apple's own mpeg4 implementation. (More)

Rainbow Artifacts/Moire - The yellow, purple (and other) coloured artifacts sometimes found on sharp black edges in video footage.

Resolution - The width and height of an image or display in pixels (more..)

RGB - Red Green Blue, a method of storing video data by its red, green and blue components which combined make any colour of light you can see. (More)

Ripping - the process of extracting (usually video) data from a file/format that is dificult to access/alter by normal methods. In particular in reference to the decryption process involved in extracting video data from DVDs. Also used to describe the same extraction process for CD audio and video or audio from games.

Sample Rate - The amount of audio samples every second in an audio stream. CDs are sampled 44100 times a seond. (More)

Saturation - Related to chroma, you can think of saturation as how a colour looks under certain lighting conditions. For instance, a room painted a solid colour will appear different at night than in daylight. Over the course of the day, although the colour is the same, the saturation changes. A sort of colourfulness, I guess.

SBC - Smart Bitrate Control, a method of accessing the Fast-motion and Slow-motion aspects of the DivX3.11a codec in order to allow variable bitrate encodes. Pioneered by Nando in his program Nandub. (More)

Scanlines - the horizontal lines that comprise one video frame. (More)

SECAM - System of video transmission used in France, similar to PAL - also plays at 25fps but has a different chroma carriers. (More)

Sorenson - A compression codec available in Quicktime (more..)

Spatial - To do with the 2d space element (i.e. the contents of a single frame) of video. For example, a spatial smoother smooths out blemishes that occur within an area of pixels. (More)

Stereo - Audio that contains two audio channels, a left and a right. (More)

Temporal - To do with the time dimension of video, i.e. the changes of the contents of a video in time. For example, a temporal smoother smooths out blemishes that occur on an individual pixel within a range (period) of frames. (More)

Timecode - The method of interpreting frames in time for use in video editing within given standards (such as NTSC, PAL, Film etc) see also Drop-Frame Timecode.

Video for Windows - The main backbone for video compression codec within windows.

Virtualdub - an open source Windows program for capturing and doing simple editing/compressing of avi files. (More)

VirtualdubAVS - an adpatation of Virtualdub by Belgador to allow easy access to AVIsynth scripts.

Wave - Another term for a (usually) uncompressed audio stream as it can be graphically represented by a waveform (more..)

YUV - A method of storing video information that gives priority (more bits of data) to the luminance of a sample. (More)