Glossary

2:35:1 aspect ratio A common widescreen aspect ratio used in theatrical-release motion pictures.

3:2 aspect ratio The common aspect ratio of digital video (DV) and DVD.

3:2 pulldown A technique to convert between film footage frame rates and video footage frame rates.

4:3 aspect ratio The common aspect ratio of an NTSC standard-definition television set.

16:9 aspect ratio The common aspect ratio of a high-definition television set and HD video formats.

16 bit A standard bit depth for digital audio recording and playback.

A

animation codec Lossless codec used for real-time playback of uncompressed RGB video.

AppleScript Scripting language developed by Apple Computer that can send commands to scriptable applications and create simple instruction sets that can be packaged into executable files.

Apple Intermediate Codec The Apple Intermediate Codec is a high-quality video codec developed by Apple for use as an alternative to native MPEG-2 HDV editing in an HDV workflow. Instead of editing the MPEG-2 HDV data directly, video is captured from a tape source and then transcoded by the codec to optimize the video data for playback performance and quality.

aspect ratio The ratio between the width and height of an image. For example, standard-definition TV has an aspect ratio of 4:3; high-definition TV has a 16:9 aspect ratio.

B

bandwidth A measurement of the amount of information delivered from a source to a destination within a period of time. Generally stated in kilobits per second (kbps) or megabits per second (mbps).

bit budgeting The process of calculating the required data rates of media to determine if it will fit within a specific bandwidth or within the limitations of a distribution format.

bit rate Also bitrate. A measurement of the quantity of data transmitted over time. See also bandwidth.

broadband A relative term used to identify the faster data delivery options provided by Internet service providers.

C

CODEC Abbreviation for compression/decompression. A program used to compress and decompress data such as audio and video files.

compression The process by which data files (often video, graphics, and audio data) are reduced in size. The size reduction of an audio or video file implemented by removing perceptually-redundant image data is referred to as a lossy compression scheme. A lossless compression scheme uses a mathematical process to reduce file size by consolidating redundant information without discarding it. Compression is irrelevant for clips imported into the Motion Canvas because all such clips are decoded into fully uncompressed frames before caching to system RAM. Compression is, however, a consideration in the final export to disc of an audiovisual composition. See codec.

D

data rate The speed at which data is transferred, often described in megabytes per second (Mbps). Higher video data rates usually exhibit increased visual quality; but higher data rates also require more system resources (processor speed, hard disk space, and performance) to process. Some codecs allow you to specify a maximum data rate for a media capture. See also bandwidth, bit rate.

deinterlace Combining video frames composed of two interlaced fields into a single unified frame.

digital video Video that has been captured, manipulated, and stored in a digital format, and that can be easily imported into a computer. Digital video formats include Digital-8, DVC Pro, DVCAM, and DV.

DV A standardized digital video format created by a consortium of camcorder vendors that uses Motion JPEG compression in a 720x480 resolution running at 29.97 frames per second (NTSC), or 720x546 resolution running at 25 fps (PAL). DV content is stored at a bit rate of 25 MB per second with a compression of 4:1:1.

F

field dominance The choice of whether field 1 or field 2 will first be displayed on a monitor. The default value should be Lower (even) for DV and Targa captures.

floating point A system of calculation that allows otherwise fixed incremental measurements within a bit depth to change in relative fashion so that a higher degree of accuracy can be achieved at the widest dynamic ranges.

frame rate The playback speed of the individual images in a moving sequence, either film or video, and measured in frames per second (fps). Film in 16mm or 35mm is usually shot at 24 fps; NTSC video at 29.97 fps; PAL video at 25 fps. HD can employ a variety of frame rates depending on the format.

H

HD (high definition) High-definition formats were created to increase the number of pixels (resolution) of video images, as well as to solve many of the frame rate and cadence problems between film and video. The two most common resolutions for HD footage are 1080 with a native resolution of 1920x1080; and 720 with a native resolution of 1280x720. Both formats can have various frame rates and be interlaced or progressive.

I

I frame See keyframe.

interlaced video A video scanning method that first scans odd-numbered picture lines (field 1) and then scans the even-numbered picture lines (field 2). The two fields are sequenced together to constitute a single frame of video.

K

keyframe A point at which a filter, motion effect, or audio level changes value. There must be at least two keyframes representing two different values to constitute a change.

L

lossless compression See compression.

lossy compression See compression.

M

metadata Information contained within a digital file that further explains the content or context of the media.

MPEG Acronym for Moving Pictures Experts Group. Also, a group of compression standards for video and audio developed by that group, which includes MPEG-1, MPEG-2, MPEG-1 Layer 3 (MP3), and MPEG-4.

multiplexed Also muxing. The interleaving of audio and video into one stream.

muxing See multiplexed

N

NTSC Acronym for National Television Systems Committee. Also, a standard format for color TV broadcasting developed by the committee and used mainly in North America, Mexico, and Japan. The NTSC format consists of 525 scan lines per frame, with 720x486 pixel resolution (720x480 for DV), and running at a 29.97 fps frame rate.

P

PAL Acronym for phase alternating line. A European color TV broadcasting standard consisting of 625 lines per frame, 720x546 pixels per frame, and running at 25 fps.

pixel Abbreviation for picture element. One dot in a video or still image.

pixel aspect ratio The width-to-height ratio for the pixels that comprise an image. Pixels on computer screens and in high-definition video signals are square (1:1 ratio). Pixels in standard-definition video signals are not square (0.9:1 ratio).

progressive frame video Also progressive scan. A format for delivering video in which all lines are drawn in sequence. It is commonly denoted with the letter “p,” such as 720p.

progressive scan See progressive frame video.

R

RAID Acronym for redundant array of independent discs. A high-performance, high-capacity data storage technology often used with nonlinear editing systems that configures a group of hard disks to act as one large drive volume.

RGB Acronym for red-green-blue, the three primary colors that make up a color image.

S

sample rate The frequency at which analog audio is monitored and converted into digital information. The sampling rate of an audio stream specifies how often digital samples are captured. Higher sample rates yield higher-quality audio. Standard audio sampling rates are usually measured in kilohertz (kHz). Standard CD sampling rate is 44.1 kHz. A rate of 48 kHz is also common in professional audio production.

SD (standard definition) The term used to differentiate traditional television broadcast resolutions from those of the high-definition formats. Standard-definition broadcast resolutions are 720x486 (NTSC) or 720x576 (for PAL). See HD.

T

TIFF Acronym for tagged image file format. A bitmapped graphics file format for monochrome, grayscale, and 8- and 24-bit color images. There are two types of TIFF images: with an alpha channel and without an alpha channel.

timecode A numbering system of electronic signals that is placed onto video content and used to identify individual video frames. Each video frame is labeled with hours, minutes, seconds, and frames, expressed in the format: 01:00:00:00. Timecode can be drop frame, non-drop frame or time of day (TOD) timecode, or EBU (European Broadcast Union) for PAL projects.

X

XSAN Apple Computer’s branded, cross-platform SAN (storage area network) solution that offers both high speed and large storage capacities.

Y

YUV The three-channel PAL video signal with one luminance (Y) and two chrominance color difference signals (UV).