Audio Interchange File Format. A standard audio format for SGI workstations.
Audio Interchange File Format with Compression. A standard audio format for SGI workstations.
The bit rate is the number of bits used to store one second of a digital video and/or audio sequence.
Numbers that are more than 8-bits long are stored as consecutive bytes. The byte order indicates whether the bytes are stored most significant to least significant (big endian) or vice versa (little endian). The concept is analogous to storing the digits in 100 as 1-0-0 or 0-0-1.
In the world of audio, a cent is a unit of pitch measurement corresponding to one one-hundredth of a semitone.
Independent streams of audio. For example, monophonic recordings contain a single channel of audio whereas stereo recordings contain two channels, left and right. The number of channels affects the file size; stereo files are twice as large as mono files.
A codec implemented for both QuickTime and AVI (microsoft windows standard for desktop video). It is an asymmetrical codec, meaning that movies encoded with it take a long time to compress, but decompress very rapidly at playback time. CinePak was originally created to compress movies for rapid decompression and playback off of CD-ROMs.
A codec is a piece of software that is capable of both compressing and decompressing movies.
The coding of data to save storage space or transmission time. Although data is already coded in digital form for computer processing, it can often be coded more efficiently (using fewer bits).
The area of the image that will be captured. The Capture tool marks the crop area with a red box. You can change the crop area by adjusting the size and placement of this box.
Demultiplexing is extracting part of a movie file, in order to create a single audio or video file. For example, extracting an MPEG audio file from an MPEG movie file (that contains audio and video).
The screen background. By default, several icons are placed on the desktop: a folder icon representing your home directory, a dumpster icon, several application icons, and an icon for each peripheral you have installed. You can place other icons on the desktop so that you can access them more easily.
In this way, the desktop is similar to an actual office desk. For example, on your desk, you might have a telephone, a container of pens and pencils, and a stack of folders or notebooks related to the projects on which you're currently working, Other items that are used less are stashed away in desk drawers.
A thin gray line in the waveform. Use this to mark the location at which you want to begin playing and recording or copying and inserting audio.
The number of images captured or displayed per second. A lower frame rate produces a less fluid motion and saves disk space. A higher setting results in a fluid image and a larger movie file.
This term refers to the way the video image was captured. Different tools for capturing video store the captured video fields differently. A full frame occurs when one image equals two fields alternated inside the image file to produce one full frame.
A standard subset of MIDI rules designed to ensure compatibility among different instruments. General MIDI instruments all store sounds in the same memory areas, and always use MIDI Channel 10 for drum parts. They can all play at least 16 sounds at once, and have at least 24-note polyphony.
An analog video signal consisting of alternating odd and even fields. The two fields are superimposed to create a single frame. See also interlaced odd and interlaced even.
An analog video signal in which the first field in a frame starts on an odd line, and thus the second field starts on an even line. NTSC recorders create interlaced odd signals. See also interlaced and interlaced even.
An analog video signal in which the first field starts on an even line. PAL recorders create interlaced even signals. See interlaced and interlaced odd.
JPEG is a compression standard developed by the Joint Photographic Experts Group. It is a lossy compression scheme designed for still images and is usable, but slow, for video (unless you have real-time JPEG hardware like the Cosmo Compress board). Software JPEG compression results in a file that is reduced to anywhere from 2 to 100 times its original size. JPEG is typically used to compress each still frame during the editing process, with the intention being to apply another type of compression (such as MPEG) to the final version of the movie. JPEG works better on high-resolution, continuous-tone images such as photographs, than on crisp-edged, high-contrast images like line drawings.
In movie compression, the key frame is the baseline frame against which other frames are compared for differences. The key frames are saved in their entirety, while the frames in between are compressed based on their differences from the key frame. In Media Convert, for example, if you set the Key Frame option to 10, every 10th frame will be a key frame. This translates to a higher level of compression and playback speed than a movie that was compressed with the Key Frame option set at a lower number. However, if you want to stop a movie in different places, in order to view different frames, a lower Key Frame option will provide better stop and start viewing.
A video/image compression method that retains all of the information present in the original data.
A video/image compression method that doesn't preserve 100% of the information in the original data.
A button that reveals a popup menu. Place the cursor over the button; then press the left mouse button.
MIDI stands for Musical Instrument Digital Interface. It is a standardized digital language (and hardware specification) that enables computers and a wide variety of electronic musical instruments/devices to communicate with each other.
Any one of 16 pathways that the MIDI standard provides for the transmission and reception of data. The number of the channel over which MIDI data should be transmitted is specified by a number in the MIDI data stream.
A MIDI controller is any piece of hardware or software that transmits MIDI data.
A product that responds to or generates MIDI data. Common examples of MIDI devices are modern keyboards and drum-pads, which include MIDI IN, OUT, and THRU ports.
In using Silicon Graphics software MIDI tools, the word MIDI interface refers to that with which the MIDI software communicates. MIDI interface could refer to the workstation's internal synthesizer or an external piece of equipment.
A hardware device that lets a computer communicate with MIDI devices such as instruments and synthesizers.
MPEG is a compression standard developed by the Motion Pictures Expert Group. It is most often used for CD-ROM and World Wide Web authoring material. MPEG-1 typically reduces the data size of an uncompressed file by a factor of 100. It is a lossy algorithm that is capable of producing higher compression ratios than both JPEG and MVC1. MPEG is well suited for video publishing, where a video is compressed once and decompressed many times for playback.
Multiplexing is combining one audio file and one video file to create a movie file that contains both audio and video. For example, combining an MPEG audio file with an MPEG video-only file to create an MPEG systems file.
MVC1 (Motion Video Compressor 1) is a Silicon Graphics proprietary algorithm that is a good general-purpose compression scheme. MVC1 typically reduces data size by a factor 5. It is a color-cell compression technique that works well for movies, but can cause fuzzy edges in high-contrast animation. MVC1 is a fairly lossy algorithm that does not produce compression ratios as high as JPEG. An advantage of MVC1 is that software-only playback is relatively fast.
MVC2 (Motion Video Compressor 2) provides results similar to MVC1 in terms of image quality. MVC2 compresses the data more than MVC1, but takes longer to perform the compression. MVC2 typically creates a file that's approximately 20 times smaller than an uncompressed file. Playback and decompression is faster than MVC1, because there is less data to read.
The video signal created when frames or images are rendered from a graphics program. Each frame contains a single field of lines being drawn one after another. See also interlaced.
A color television standard or timing format encoding all of the color, brightness, and synchronizing information in one signal. Used in North America, most of South America, and most of the Far East, this standard is named after the National Television Systems Committee, the standardizing body that created this system. NTSC uses a total of 525 horizontal lines per frame, with two fields per frame at 262.5 lines each. Each field refreshes at 60 Hz (actually 59.94 Hz).
A color television standard or timing format developed in West Germany and used by most other countries in Europe, including the United Kingdom but excluding France, as well as Australia and parts of the Far East. PAL uses a total of 625 horizontal lines per frame. Each field refreshes at 50 Hz. PAL encodes color differently from NTSC. PAL stands for Phase Alternation Line or Phase Alternated by Line, by which this system attempts to correct some of the color inaccuracies in NTSC. See also NTSC.
A “picture element”; images are made of many tiny pixels. For example, a 13-inch computer screen is made of 307,200 pixels (640 columns by 480 rows).
The pixel aspect describes the shape of each pixel. Most images are made of square pixels. Another possible pixel aspect is “CCIR 601/525,” if the video source for your images was a CCIR 601 video device (with NTSC timing).
When using MIDI tools from Silicon Graphics, Inc., the term preset refers to the type of sound (sometimes called voice, sound patch, or timbre) assigned with the tool. For example, if you select the Harmonica preset, and then play a few notes with the MIDI Keyboard, the sound of the notes will resemble the sound of a harmonica. MIDI Keyboard and Synthesizer Panel come with many presets for you to choose from.
A desktop video standard developed by Apple Computer. QuickTime Animation was created for lossless compression of animated movies and QuickTime Video was created for lossy compression of desktop video.
A name for the standard computer keyboard, named by first six keys from left on the top alphabetic row.
The simulation of natural reverberation (such as the echoing caused by sound reflection), in order to add a sense of spaciousness and ambience to a sound.
RLE stands for Run-length Encoding. RLE is also known as Animation, and was created specifically for compression and decompression of animation clips. It is best used as a lossless codec of sequences of drawn or rendered still images.
The speed at which audio samples are recorded and played back. This is analogous to video and film frame rates. Higher sample rates allow high frequencies to be represented with better accuracy and, therefore, higher fidelity.
The number of bits used to represent a single sample of audio data, typically expressed in multiples of 8-bits (8, 16 or 24). Larger widths allow for greater dynamic range and precision, both of which influence audio quality.
The Movie Maker and Movie Player selection bars represent timelines of the sound and/or image tracks of a movie. Click and drag out a highlighted section of a selection bar to select a portion of a movie or sound track.
A digitally-based device used to record, edit, or play MIDI data sequentially.
This term refers to the way the video image was captured. Different tools for capturing video store the captured video fields differently. A split field occurs when one image equals two fields, which are stored as two separate pictures, one for each field; one stacked on top of the other.
In the world of MPEG compression, systems refers to a movie file containing interleaved MPEG audio and MPEG video. Systems is short for the technical compression term systems bitstream.
The speed at which a note has been pressed or released. Velocity can alter the volume and/or brightness of a sound.