# interleave
A method of storing video and audio data together in a video file, such that a segment of video data is followed by a segment of audio data. By interleaving video and audio data, Video for Windows can maintain a smooth transfer of audio/video information while playing a video sequence from a hard disk or CD-ROM drive.	

# track
A linear depository of information within a video sequence. All video sequences have at least two tracks: a video track storing frames of video data, and an audio track storing segments of audio.	

# frame
A single unit of information within a video sequence. A video sequence consists of many frames of video and audio data; when the frames are played in sequence, you see an unbroken video sequence with accompanying audio playback.	

# palette
A collection of color information for a picture or video sequence.
Video for Windows can use an 8-bit palette format. With this format, up to 256 color values can be stored in a table. Images within the video sequence reference the entries in this table; each pixel has an 8-bit value identifying which palette color to draw. The 8-bit palette format uses less storage space than the 16-bit and 24-bit formats, which do not use a palette (rather than reference a value in a table, they store color information directly with the pixel).	

# bitmap
An image format commonly used for scanned photographs and artwork. A bitmap divides a picture into a grid of pixels, with each pixel assigned a specific color. Bitmaps usually have .BMP or .DIB extensions.	

# waveform audio
A technique of re-creating an audio waveform from digital samples of the waveform. The sound track for a video sequence is stored as waveform audio data.	

# insert mode
One of two VidEdit editing modes. In insert mode, space is provided for data added to the video sequence; existing data is retained and pushed later in the sequence. When data is removed from a video sequence, data following the deletion is shifted back to cover the empty area.	

# overwrite mode
One of two VidEdit editing modes. In overwrite mode, data added to the video sequence replaces any existing data at the insertion point. When data is removed from a video sequence, the frames storing the deleted data are retained (so an empty frame results).	

# frame rate
The number of frames recorded for each second of video playback. Higher frame rates can provide smoother motion than lower frame rates.	

# dithering
A technique for simulating an unavailable color by combining two or more available colors.	

# sampling frequency
The rate at which digital-audio samples are taken. Higher sampling frequencies provide better fidelity but require more storage space.	

# sample size
The amount of storage space used for each digitized portion of the audio track. Larger sample sizes provide greater dynamic range and, therefore, better audio reproduction (but they require more storage space).	

# stereo (audio)
Audio format in which two channels are used. Stereo audio can provide better sound reproduction but it requires twice the storage space as monaural (mono) audio.	

# mono (monaural audio)
Audio format in which a single channel is used. Monaural audio requires half the storage space as stereo audio, which uses two channels of audio information.	

# codec, or Compressor/Decompressor
A software component that provides compression services (while creating a video sequence) and decompression services (while playing a video sequence). The Video for Windows architecture provides for the use of multiple codecs, so you can choose the one that's most appropriate for your application.	

# data-transfer rate
The speed at which data is transferred from a storage device to the processing hardware of the computer. Devices with higher data-transfer rates can provide better playback quality.	

# key frame
A fully-drawn frame stored as a reference point for successive frames. Most video sequences store only the changes from frame to frame (they don't store a complete image for each frame). A key frame stores a complete frame image, so an application can jump to the key frame and obtain a fully-drawn image for that point in the video sequence.	

# direct-to-disk capture
VidCap transfers video data from the capture board directly to the MS DOS file system, using MS-DOS memory buffers for intermediate storage. If the hard disk falls behind during capture, VidCap automatically switches to the Capture To Memory option.	

# capture to memory
Rather than transfer data directly to disk, VidCap allocates memory using Windows (high memory) and copies video and audio data into these memory buffers. When these memory buffers are filled, however, the number of dropped frames quickly increases.	

# video sequence
A digital-video file created using Video for Windows. Video sequences consist of a series of frames of audio and video data. When played in sequence, the images and sound produce an animated video on the computer screen. Video sequences have a filename extension .AVI, for Audio-Video Interleaved.	

# audio and video source
The data stream captured as a digital-video sequence. Video sources include videotape and videodisc players, video cameras, and television tuners. Audio can also be captured from these devices.	

# capture board
A piece of computer hardware that receives video signals and stores incoming video images in a memory area that can be accessed by system and application software.	

# audio board
A piece of computer hardware that plays and receives audio signals. Audio boards have circuitry that convert analog signals into digital format (for recording), and convert digital signals into analog format (for playback).	

# capture file
A file created on the hard disk for the purpose of storing captured video and audio data. This file provides storage space for the capture session, allowing the capture to proceed without taking time to allocate additional disk space for video and audio data.	

# Media Control Interface (MCI)
A standard control interface for multimedia devices and files. MCI lets a multimedia application control a variety of multimedia devices and files. VidCap uses MCI to play video previews and to control source devices such as laserdisc players and videocassette recorders.	

# pixels
A single dot, or unit, within the computer display. The display is made up of a grid of pixels, each of which has its own color value.	

# compression
Compression reduces the storage requirements of a video sequence. Compression reduces the file size of the video sequence and also reduces the amount of data that must be transferred to play video frames. Because some storage devices (particularly CD-ROM drives) have a relatively low data-transfer rate, reducing the amount of data that must be transferred helps avoid skips and slowdowns during playback.	

# real-time capture
With real-time capture, you capture video data from a source device playing at normal speed. For real-time capture, you need a computer system fast enough to keep up with the data coming in from the source device. Data must be captured and stored on the hard disk before the next frame of information is received.	

# step-frame capture
With step-frame capture, you capture video one frame at a time, generally from a paused source device. You capture a frame, advance the source device to the next frame, and then capture the next frame. Step-frame capture provides an alternative if your computer system cannot capture in real time without losing data. Step-frame capture also lets you increase the frame size, use a larger color format, or perform software compression (because the system has more time to store the captured data).	

# video overlay
The capability of watching a video source in a window on the computer. The video signal from the VCR, camcorder, or other source device is synchronized with the computer display and displayed within a window.	

# frame buffer
The memory area on the capture board used to store video data captured from the video source signal.	

# 8-bit color format
A color format in which colors are stored in a separate table called a palette. The pixels within the video frame reference the entries in the palette (rather than store color information themselves). The palette format provides a maximum of 256 unique colors within a video frame. Each color entry in the palette can use any of 16 million colors. Most multimedia computers can display 8-bit images; fewer support the 16- and 24-bit formats.
The term "8-bit" refers to the amount of information encoded with each pixel. Each pixel contains an 8-bit number that references one of the entries in the color table.	

# contiguous
Residing within a single unbroken area of the disk. Hard disks are organized into sectors of data. A file might be stored across many sectors, and those sectors can reside in different areas of the hard disk. Because seeking to a different sector can take time away from the capture session, resulting in data loss, it's important to defragment the hard disk before capturing. This ensures the capture file resides in a contiguous area of the hard disk.	

# fragmented
Residing on non-contiguous sectors of the hard disk. When a fragmented file is written or read, the computer must skip to different areas of the hard disk to access the sectors making up the file. Seeking to a different sector takes time and can result in the loss of incoming video data.	

# defragmentation
Defragmentation utilities rearrange files so they reside in contiguous sectors of the hard disk. The DEFRAG command included with MS-DOS version 6.0 is one such utility.	

# 16- and 24-bit color formats
Video for Windows color formats that store color information directly with the pixel (rather than in a separate color table, as is used with the 8-bit format). This means there is no limit to the number of unique colors within a video frame.
The 16- and 24-bit formats are called true-color formats because they preserve more of the original colors of the video signal. The 16-bit format provides a range of 32,767 color choices per pixel; the 24-bit format provides a range of 16 million color choices per pixel.	

# identity palette
A palette containing the standard system colors arranged in a specific location (the top ten and bottom ten cells of the color table). An identity palette can be processed more quickly by Windows and can therefore provide improved display performance over a standard palette.	

# dropped frames
Data lost during video capture. When capturing video, the system might not be able to finish processing the current video frame before receiving the next video frame from the source device. The incoming frame is ignored, or dropped, and a blank frame is stored in its place.