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This section provides terms and definitions used in video and audio editing.

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1.33 -- Aspect ratio used for Standard Definition Television; one third wider than it is high (4:3). See also aspect ratio.

1394 -- See FireWire.

16:9 -- Widescreen aspect ratio used for High Definition Television (HDTV); almost twice as wide as it is high (1.78:1). See also aspect ratio.

1.78 -- Widescreen aspect ratio used for High Definition Television (HDTV); almost twice as wide as it is high (16:9). See also aspect ratio.

2-3/3-2 pulldown -- Process used to convert material from film to interlaced NTSC display rates, from 24 to 30 frames per second. This is done by duplicating fields, 2 from one frame and then 3 from the next frame (or 3 and then 2). Both terms are often used interchangeably to describe the effect. See also inverse telecine.

4:3 -- Aspect ratio used for Standard Definition Television; one third wider than it is high (1.33:1). See also aspect ratio.

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A/B editing -- A style of video editing in which you edit together clips in pairs - A and B - typically with a transition from one to the next. This is commonly associated with video of an interview subjected that is covered with B-Roll to either illustrate what is being discussed or to cover up edit points.

AIFF -- Acronym for Audio Interchange File Format; Macintosh audio file format. Can be used for uncompressed and compressed data.

alpha channel -- Extra information stored with an image to define  transparent areas used for keying and superimpositions. Also called an alpha mask. Sometimes present in files prepared using a tool such as Adobe Photoshop or Illustrator. See also key.

amplify -- Increase the audio volume or boost gain.

analog media -- Audio and video tapes that must be digitized and converted into digital format for processing by a computer. Machines that use this media read analog waves rather than digital 1's and 0's. Analog media is directly affected by the quality and age of the media.

animate -- To move and manipulate an object over time, such as a title, a superimposed logo, or a transition between frames.

anamorphic -- A method of storing widescreen video on DVDs or standard definition video tape. The original 16:9 widescreen image is squeezed horizontally and stored on disc or tape in the standard 4:3 video resolution. The player then stretches it back out to the original aspect ratio for display, either to a widescreen monitor or typically letterboxed on a standard television monitor. See also aspect ratio.

antialias -- To smooth out a jagged or stair-step appearance or motion between adjacent points so that it appears continuous.

aspect ratio -- The shape of an image or frame, expressed as the width-to-height ratio. Widescreen film uses a 16:9 aspect ratio (1.78:1), whereas standard television uses 4:3 aspect ratio (1.33:1). A DVD disc can store video in either standard or widescreen format. See also anamorphic, letterbox, Pan and scan.

attenuate -- To reduce audio strength or volume or lower gain.\

audio advance -- See J-cut and L-cut.

audio waveform -- A graphical representation of an audio clip, helping to visualize the sound in the clip by showing the signal levels.

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.

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balance -- To distribute two channels of a stereo clip between the left and right channels, either evenly or favoring one channel over another. See also pan.

bandpass effects -- Audio effects designed to remove specific frequencies from an audio clip (manifested as hisses, whines, and hums).

bandwidth -- The amount and rate of data that can be processed or transmitted by a given device. An analog modem has very little bandwidth compared to a high-speed cable modem, for instance, so the former cannot download video from the Internet nearly as quickly as the latter. In TV, a broadcast station does not have as much bandwidth to transmit a television signal as an edit system has to process it, so it must be compressed prior to sending out over the air. See also bit rate and compression.

batch capture -- The automated process of capturing an entire group of clips (such as from a DV camcorder or deck) as defined by a batch list.

batch list -- A list of clips with the timecode values for each In and Out point (also called a timecode log) to be used in a batch capture process. See also batch capture, log, timecode.

bin window (clip window) -- The area of the editing system used to import and organize folders of source clips.

bit -- A binary digit. The fundamental element of computer logic and numbers. Represents one of two values: zero or one, off or on, false or true. Bits are combined to create pieces of data. See also byte.

bit rate -- The speed at which data is transferred, as in bytes per second. Also called data rate. For example, the speed to download or stream a video file over the Internet, or the speed at which the file must play from a hard disk. Higher quality material requires higher bit rates. When you create a video or audio file, you can specify the target bit rate at which the file will be played. Standard Definition video requires a lower bit rate than High Definition video. MP3 audio uses a lower bit rate than .wav or .cda files. See also bandwidth.

blue screen -- A blue colored backdrop that can be made transparent so that it can be replaced with another image. For example, you can cut out a subject from the blue screen background and composite it into another scene. See also matte, key.

BMP -- The standard Windows bitmap still image file format. Bitmap files are not compressed, and are therefore significantly larger than the same image stored in formats such as GIF and JPEG.

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.

byte -- A data element containing eight bits, or 256 distinct values. Commonly used to store a single text character. Computer data transfer rates are traditionally measured in bits, as in Mb for Megabits (millions of bits, with a lower-case "b"); whereas computer data storage is traditionally measured in bytes, as in MB, for megabytes (millions of bytes, with an upper-case "B"). See also bit, GB, KB, MB.

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capture -- To digitize, or import and convert, video and/or audio into digital format on your computer from external devices, such as a camcorder or VCR. You typically use a special video capture card to input analog video into your computer, and then convert and save it into digital files on your disk. With DV camcorders and digital decks, you transfer digital data directly into your computer over a FireWire (1394), HDMI or other digital interface. See also import.

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.

channel -- The subcomponents of a clip. For images, an alpha channel can contain a matte or mask image to key certain regions of the image to be transparent. For audio, the separate left and right channels of a stereo clip.

chrominance -- The color of a video signal. Video signals are split into separate luma and chroma (color) components for higher-quality and more efficient transmission and encoding. The chroma signal is typically split into two components or color difference signals, such as YUV format. See also luminance.

clip -- A short piece of video and/or audio, often containing an individual scene. When creating a video project, you import clip files into bins, and often trim longer clips into individual scenes. You then edit the clips together on the Timeline to play in sequential order to tell the "story" of your production, with transitions between clips and other added effects.

Clip window -- The area of the editing system used to import and organize folders of source clips.

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.

composite -- See superimpose.

composite video -- A consumer video signal that combines the brightness (luminance or luma) and the color (chrominance or chroma) video information into one signal. Because the signal is not modulated, composite video provides higher quality than RF video. Also called Baseband video. See also component video, DV, RF video, S-Video.

component video -- A professional video signal that separates the video signal into three separate signals (and three separate wires) to avoid any quality loss from mixing signals. The components can be RGB (red, green, and blue); luma (Y) and two chroma signals, such as Y, Y-R, Y-B; or other formats including YUV, YCbCr, or Y Pr Pb. See also composite video, DV, RF video, S-Video.

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.

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.

crawl -- To scroll a line of title text sideways, left or right across the screen. See also roll.

credit -- Title text that identifies the people who contributed to a production. Usually scrolled at the end of a show.

crop -- To make an image physically smaller by trimming away one or more edges. This reduces the dimensions of the image, and reduces the size of the computer file.

cross-fade --  See fade.

cut -- To switch instantly from one clip to another. A video cut appears suddenly onscreen without any other kind of transition effect. The cut is the most basic kind of transition for changing scenes and dropping titles onto the screen. See also fade, transition.

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decode -- See decompress.

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.

deinterlace -- To process interlaced television video, in which each frame contains alternating pairs of lines from two separate fields captured at slightly different times. The motion between fields can cause visible tearing when displayed on a computer monitor. Deinterlacing uses every other line from one field and interpolates new in-between lines without tearing. See also interlace, NTSC.

delay -- An audio effect that provides an echo of a sound after a specified time period. Delay can also refer to the speed difference between audio and video transmissions. See also lip sync.

digital media -- Audio and video sources such as audio CD, digital tape formats, and DVD that store the audio and video in the form of 1's and 0's. As a result, the data can be imported and processed directly by a computer, and copied without any loss from one generation to the next. See also analog media, DV.

dissolve -- A video transition in which one video clip fades into the next. See also fade, transition.

dub -- To duplicate or make a copy of a production, traditionally from one tape (usually a master tape) to another tape.

duration -- A length of time. For a clip, the length of time that it will play, determined by its overall length. Or if the clip has been trimmed, the difference in time between its In point and Out point. See also timecode.

DV -- A Digital Video tape and compression format for consumer and professional video equipment. This can refer to both consumer and professional Standard Definition and High Definition formats. See also analog media.

dynamic range -- The difference between the softest and loudest sounds. Decrease to compress the range and reduce noise, or expand to emphasize volume differences.

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effect -- The result of processing audio and video clips to enhance, improve, or distort them. See also filter.

encode -- See compress.

equalize -- To adjust the tonal quality of an audio clip. An equalizer effect can to boost or cut the original signal at different frequency bands.

export -- To save your production to a file or to an external video device or storage media. See also import.

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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.

fade -- A gradual transition from one clip to another. With video, the clip changes from transparent to fully opaque (or vice versa) to fade in or out. With audio, the gain changes between silence and full volume. A crossfade brings a second clip in while fading out the first, with each clip momentarilly being equally visible or audible at the center of the transition.

field -- For interlaced video sources, a full frame is constructed from alternating odd and even lines from two video fields captured at slightly different times. See also interlaced video.

filter -- A transformation applied to a video or audio clip to enhance it or create a visual or auditory effect. See also effect.

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. 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.

fps -- Frames per second. See frame rate.

frames -- The individual video images that make up a moving sequence. Video formats and individual clips are typically described in terms of the resolution of the individual frames, and the frame rate at which they are played. See also frame rate, field.

frame rate -- Playback speed as determined in frames per second. See also sample rate.

four-point edit -- A method of setting In and Out points to precisely control where and how frames are inserted into a Timeline. In a four-point edit, you set all four In and Out markers, and (in some editing systems) the clip will usually be adjusted in speed to fit the space provided in the timeline. See also three-point edit.

freeze frame -- A technique in which a particular frame of video is held onscreen. Sometimes the audio portion of the scene continues playing.

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gain -- Overall audio output volume. Increase gain to amplify a clip, or decrease gain to attenuate a clip, making it quieter.

gamma -- A display setting related to the brightness of the middle tones of an image. You can adjust the gamma of an image to lighten or darken the midtones (the middle-gray levels), without significantly changing the dark and light areas (the shadows and highlights).

garbage matte -- A mask used in a keying operation to remove a region of a frame that contains unwanted objects. Also referred to as a cutout.

GB -- Gigabytes (billions of bytes). In computer use, a gigabyte actually represents the closest binary power of 2 to a billion, or 1024 cubed. In advertising DVD and hard drive disc capacity, however, the number of "GB" is actually used to specify a different value, a billion decimal, based on a factor of 1000. Therefore, actual capacities are usually lower than those advertised. See also byte, KB, MB.

GIF -- Acronym for Graphics Interchange Format. A still image file format commonly used on web pages for simple illustrations and animations.

gradient -- Gradual change from one color (or intensity level) to another. Gradient colors can also become opaque or transparent, varying in translucency from one side to the other.

green screen -- A green colored backdrop that can be made transparent so that it can be replaced with another image. For example, you can cut out a subject from the green screen background and composite it into another scene. See also matte, key.

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Hz -- Hertz. A measurement used for audio sampling rate, as in the number of audio samples per second. See also sample rate.

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IEEE 1394 -- See FireWire.

iLink -- See FireWire.

import -- To bring media elements into your current working space. Video editors can import video and audio clips, still images, and animated sequences in a variety of formats. See also capture, export.

In point -- A placeholder used to mark a specific timecode as the starting point of a segment in a longer sequence. You can use In and Out points to mark a clip to be captured from a source tape, to mark part of a clip to be trimmed, to mark the location of where to place a new clip or to mark a portion of the Timeline to be played. See also marker, Out point.

interlaced video -- A technique used for television video formats, such as NTSC and PAL, in which each full frame of video actually consists of alternating lines taken from two separate fields captured at slightly different times. The two fields are then interlaced or interleaved into the alternating odd and even lines of the full video frame. When displayed on television equipment, the alternating fields are displayed in sequence, depending on the field dominance of the source material. See also progressive video.

interpolate -- To automatically create graduated steps between two or more keyframes to create smooth transitions for video, audio, and motion effects. A video device can also interpolate lines of video in order to upconvert it from a lower to higher resolution.

inverse telecine -- The process used to reverse the effect of 3-2 pulldown, removing the extra fields inserted to stretch 24 frame per second film to 60 field per second interlaced video. See also 2-3/3-2 pulldown.

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J-cut -- A split edit in which the In point of a clip is adjusted to overlap the preceding clip so that the audio portion of the later clip starts playing before its video as a lead-in to the visual cut. Also called an audio advance. See also L-cut.

jog -- To move slowly through a program, as with frame advance or frame reverse VCR controls. See also shuttle.

JPEG -- A still image file format developed by the Joint Photographic Experts Group that can compress photographic images into much smaller file sizes while sacrificing only a little image quality. Commonly used for photographs on web pages and in e-mail. See also GIF.

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kerning -- The spacing between adjacent characters in a text string, as in a title.

key -- To specify a region of an image or video clip to be used as a mask for transparency. Used to make part of the scene transparent or semitransparent, and then composite it with other superimposed images or video tracks. The region can be specified using features such as color (a color key) or intensity, or with a separate alpha mask or image matte. See also blue screen, green screen, matte.

keyframe -- A point along a timeline or path that defines where and how the settings for an effect will change. One or more settings can then be interpolated from keyframe to keyframe to create the appearance of a smoothly change over a series of frames or along a motion path. See also interpolate.

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L-cut -- A split edit in which the audio Out point of a clip is extended beyond the video Out point, so that the audio cuts after the video and continues playing over the beginning of the next clip. See also J-cut.

leader -- The beginning of the physical tape on a videocassette or extra material before the beginning of a clip. A tape leader is a strip of nonrecording material that connects the actual recording tape to the spindle on the cassette. In film, the leader is an extra length of film stock used to thread the film through the projector before the start actual production element.

letterbox -- A technique used to display a widescreen video image (with a 16:9 aspect ratio) on a standard television display (with a 4:3 aspect ratio). The widescreen image fills the width of the screen, with black bars above and below it. See also aspect ratio, pan and scan.

Line level -- An analog audio connection intended for connecting interconnecting audio equipment, and without the amplification required to connect to speakers. This is unlike a mic level connection that needs to be powered in order for it to connect to speakers.

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 MPEG try to eliminate information in subtle ways so that the change is barely perceptible, and sound or video quality is not seriously degraded. However, excessive compression with lossy formats quickly becomes noticable to the viewer/listener.

luminance -- The intensity or brightness of a video signal, usually represented by the letter Y. Video signals are split into separate luma and chroma (color) components for higher-quality and more efficient transmission and encoding. In YUV color format, for example, the color information stored in U and V (the color difference signals).

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marker -- A placeholder used to mark a specific timecode in a sequence. Use to keep track of changes, events, or synchronization points in a longer sequence. See also In Point, Out Point.

mask - An image which defines areas in a frame to be used as a transparency key or matte. Each pixel in the mask image indicates the degree of transparency to be used for the corresponding pixel position in each frame. See key, matte.

master -- For video, the original video or audio source, or final video production, also known as the first-generation tape. The master tape is a high-quality source to which you should return whenever you want to make more copies. A master can also be store on digital media, as long as the quality of the working timeline is preserved.

matte -- An image mask used to define the transparent areas of each frame to be used in superimposing multiple clips. See also key.

MB -- Megabytes - millions of bytes. In computer use, a megabyte actually represents the closest binary power of 2 to a million, or 1024 squared. See also byte, GB, KB.

mic. -- Microphone audio input or the microphone itself.

monitor window -- Used to preview and edit the Source view of individual video clips and the Program view of the material being assembled on the Timeline.

mono -- Monophonic audio - a single channel of audio. See also stereo.

motion blur -- The effect of tracking a speeding object and thus blurring the background because of the motion.

MOV -- QuickTime Movie format. See QuickTime.

MP3 -- An audio file format, especially popular for downloading songs from the web and for storing music in and portable music players. Named for Moving Picture Experts Group (MPEG) 1, Layer 3. Uses lossy compression to significantly reduce file size, but often with little perceptible loss in sound quality. Used to store large song collections on hard disc, download audio to portable audio players, and save multiple hours of music to CD. Some consumer audio players and set-top DVD players can play MP3 audio files stored on CD-R/RW discs. See also WAV, Windows Media Audio.

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. MPEG-3 (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 resolutiosn 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. MPEG-4 is also becoming a common format for cable and satellite providers to distribute High Definition video services.

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narration -- A voice that explains what is happening on a video.

NTSC -- A television video format used in the United States and elsewhere. Displayed 525 lines of resolution at 60 fields per second, totalling 30 frames per second (actually a fractional value near 29.97). Named for the National Television Standards Committee. See also PAL.

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. In digital video, the effect is often referred to as splatter.

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opaque -- Regions of a superimposed image that are solid (not transparent), and therefore cover over the underlying image. See also transparent.

Out point -- A placeholder used to mark a specific timecode as the end point of a segment in a longer sequence. You can use In and Out points to mark a clip to be captured from a source tape, to mark part of a clip to be trimmed, to mark the location of where to end an inserted new clip, or to mark a portion of the Timeline to be played. See also marker, In point.

overscan -- The outer edges of a video image that are typically cut off by consumer television sets in order to ensure that the image fills the entire display. See also safe area.

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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.

pan -- To move the apparent location of a mono audio track to position it between the left and right stereo channels. With stereo clips, you adjust the balance between the two channels. See also balance.

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.

PICT -- The standard Apple Macintosh still image Picture file format.

pixel -- The individual picture elements, or "dots" of color or grayscale, 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.

preroll -- To start a tape spinning up to speed before beginning playback or capture to ensure that the operation is synchronized properly. Often this involves inititally cueing up a tape a few seconds before the actual start of the video element.

preview -- To play a program on the Timeline and view the appearance of the final production, including transitions and effects.

Program view -- The Monitor window view that displays the production being assembled on the Timeline. Depending on the current settings, this can be a simple preview of the cuts between adjacent clips, or a fully rendered preview with transitions and effects. See also Source view.

progressive scan -- Video display in which the entire screen in refreshed (redrawn) at once. Typically used for computer monitors and high-end video systems. See also interlaced video.

progressive video -- Video consisting of complete frames, not interlaced fields. Each individual frame is drawn top to bottom in a single pass. See also interlaced video.

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QuickTime -- Multiplatform, multimedia Movie file format from Apple Computers (.MOV).

QWERTY -- The standard layout for English language keyboards. This refers to the arrangement of the first row of letters, which spells QWERTY.

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