Audio Video Interleave (AVI) is a means of digitally storing multimedia audio and video content in a file for playback. Introduced in the early 1990s, the AVI format is a built-in feature of the Windows computer operating system (OS). AVI format files use the .avi file extension and consist of a header tag followed by a series of information blocks. The header part of the AVI format file provides details about the content of the file, such as width, height, and frame rate, while the information blocks store the actual audio and video data. One of the main advantages of the AVI format is its ability to be played on most computers in the world.
To play a media file of any format, including AVI format, compatible software that understands the details of the file content is required. When the appropriate software program is not available to open and play a media file, the user is presented with a message box stating that Windows can open the file. Options are provided to allow the user to select the program from a list of available programs or use the web to locate the program. The AVI format usually eliminates the need to select a program.
In the years after the AVI format began, many video techniques were introduced that were not conceived during the definition of the AVI specification. Also, the compression systems used to optimize space requirements when writing AVI files are not as effective as the techniques used in developing newer multimedia formats. As such, the AVI format requires approximately 5 megabytes (MB) of storage space per hour of video and does not support the ability to specify media details such as aspect ratios, time codes, or audio sample rates below. 32 kilohertz (kHz).
Many new media file formats are making their way onto the Internet, including Ogg, MOV, and NUT. Motion Picture Experts Group (MPEG), however, is emerging as a default standard and its popularity is growing. Software programs to support the creation and playback of MPEG media files are included in Windows and Mac operating systems.
