A
AAC
AC3
AfroPic
AIFF
Aliasing
Anamorphic
Angle
Antialiasing
Artifact
ASF
Aspect Ratio
ASPI
ASV
ASX
ATA
ATAPI
ATSC
AUDIO_TS
Author
AVI

A
AAC
Advanced audio coder. An audio-encoding standard for MPEG-2 that is not backward-compatible with MPEG-1 audio.



AC3
See Dolby Digital . A .ac3 file is a Dolby Digital audio file.



AfroPic
A mac video conversion program. It can easily demux files and has various other functions available.



AIFF
Macintosh AIFF Resource ( .aif, .aifc, .aiff) Audio Interchange File Format (AIFF) is an audio file format that was developed by Apple Computer. This format may be used to store high-quality sampled audio and musical instrument information.



Aliasing
A distortion (artifact) in the reproduction of digital audio or video that results when the signal frequency is more than twice the sampling frequency. The resolution is insufficient to distinguish between alternate reconstructions of the waveform, thus admitting additional noise that was not present in the original signal.



Anamorphic
Process where a "wide" video image (typically in a 16:9 widescreen format) is compressed or squeezed horizontally to fit a more narrow video display standard but expands to full size when played over a wide video display.

Letterboxing an image enables the viewer to see the entire widescreen presentation of a movie as it was intended and as it was shown in the theater. However, in order to fit a "wide" image in a "narrow" television, the wide image must be centered in the screen with black bars above and below it (in order to fit a wide image in a narrow screen, the width must match the width of the narrow display so the height of the image is necessarily less than that of the more narrow and square video display). While this method allows the user to see the entire image as it was meant to be seen (narrow 4:3 aspect ratio television sets normally show pan & scan movies), the image loses some horizontal resolution to the black bars.

While not much can be done about this on standard 4:3 televisions, there are wider 16:9 displays, which can show an entire movie image with no bars thus allowing the picture to fill the screen. To take advantage of this, a movie can be distributed in a squeezed anamorphic format without black bars. On a more square 4:3 television this results in an image which seems tall and pinched with actors looking too narrow and objects distorted. However, when played on a widescreen display, the picture is stretched out to its proper width resulting in a widescreen image with no bars and the maximum possible resolution. This technique is being used primarily with DVDs to provide superior quality video to users of widescreen televisions. DVDs featuring this anamorphic version allow a user to watch the image in a letterboxed or pan & scan format on their traditional more square 4:3 televisions when this is selected while allowing users with widescreen televisions to enjoy the full benefit of their displays. AudioVideo101 - Ultimate Guide



Angle
A scene recorded from different viewpoints. Each angle is equal in time length and an Angle Block may contain up to nine (9) angles.



Antialiasing
Smoothing or reducing disturbing picture effects. By means of calculation of intermediate values along the sharp edges of types and graphics, these edges can be smoothed out, thus generating a smoother picture. The pixel structure along tilted or bent edges is mixed with the surrounding colors. When creating DVD Menu text, antialiasing must not be used.



Artifact
An unnatural effect not present in the original video or audio, produced by an external agent or action. Artifacts can be caused by many factors, including digital compression, film-to-video transfer, transmission errors, data readout errors, electrical interference, analog signal noise, and analog signal crosstalk. Most artifacts attributed to the digital compression of DVD are in fact from other sources. Digital compression artifacts will always occur in the same place and in the same way. Possible MPEG artifacts are mosquitoes, blocking, and video noise.



ASF
Advanced Streaming Format (ASF): This file format stores audio and video information, and it is specially designed to run on networks like the Internet. This file format is a highly flexible and compressed format that contains streaming audio, video, slide shows, and synchronized events. When you use .asf files, content is delivered to you as a continuous flow of data. You no longer have to wait for your audio and video files to fully download before you start to view them. When an Audio Video Interleave (.avi) file is compressed and converted to an .asf file, the file begins playing after only a few seconds. The file can be unlimited in length and can run over Internet bandwidths. Microsoft ASF information - MS Sample



Aspect Ratio
The width-to-height ratio of an image. A 4:3 aspect ratio means the horizontal size is a third again wider than the vertical size. Standard television ratio is 4:3 (or 1.33:1). Widescreen DVD and HTDV aspect ratio is 16:9 (or 1.78:1). Common film aspect ratios are 1.85:1 and 2.35:1. Aspect ratios normalized to a height of 1 are often abbreviated by leaving off the :1.



ASPI
ASPI stands for Advanced SCSI Programming Interface. Originally developed by Adaptec. It is a software layer that enables programs to communicate with SCSI and ATAPI devices(CD and DVD Drives and other storage peripherals). Bart's page about ASPI .



ASV
(Audio Still Video) A still picture on a DVD-Audio disc.



ASX
Advanced Stream Redirector (ASX): When you use .asx files, you are directed to streaming media content, usually on multimedia Web sites. The .asx files are simple text files that contain server and media information. They are metafiles (a file that provides information about Windows Media files and their presentation) that are similar to Windows Media Redirector (.wvx) files.

If you want to find out more about the streaming content you can open an ASX file in a text editor and often find the filenames of the actual streaming content (often with an .asf extension denoting an ASF file).



ATA
A dvanced T echnology A ttachment or called Parallel ATA is a disk drive implementation that integrates the controller on the disk drive itself. There are several versions of ATA:
ATA, also called IDE.
ATA-2, also called EIDE.
Ultra-ATA, also called Ultra-DMA, ATA-33, and DMA-33.
ATA/66ATA/100
http://www.webopedia.com/TERM/A/ATA.html

See SATA .



ATAPI
Advanced Technology Attachment Packet Interface is a interface to support CD Drives and DVD Drives using the computers current ATA(IDE/EIDE) connections. ATA was originally designed for hard drives only, but with help of ATAPI it is possible to connect other devices to the ATA(IDE/EIDE) connections.



ATSC
The Advanced Television Systems Committee, Inc., is an international, non-profit organization developing voluntary standards for digital television. Specifically, ATSC is working to coordinate television standards among different communications media focusing on digital television, interactive systems, and broadband multimedia communications. ATSC Digital TV Standards include digital high definition television ( HDTV ), standard definition television ( SDTV ), data broadcasting, multichannel surround-sound audio, and satellite direct-to-home broadcasting.
http://www.atsc.org/aboutatsc.html



AUDIO_TS
UDF file name used for the DVD-Audio directory on a DVD disc volume. DVD-Audio is a separate format from DVD-Video so on a standard DVD-Video is the AUDIO_TS folder empty.



Author
To format video into a form ready to burn onto a recordable disc or to stream onto the Internet. VCD, SVCD and DVD Author is to format video into its standard file structure and also add optional menus, chapters, audio tracks, subtitles, slideshows and much more.

VCD File structure
SVCD File structure
DVD File structure

VCD Authoring guides
SVCD Authoring guides
DVD Authoring guides



AVI
Audio Video Interleaved - A multimedia file format for storing sound and moving pictures in RIFF format developed by Microsoft . An AVI file can use different codecs and formats so there is no set format for an AVI file unlike for example standard VCD video which sets a standard for resolution, bitrates, and codecs used. Microsoft AVI information - MS Sample File