An AVI (Audio Video Interleave) file is a container format that allows audio and video files to be played simultaneously. Also, because AVI files are file containers they hold subtitles and menu files. AVI files are similar to DVD files but are technically derived from RIFF (Resource Interchange File Format) files. A file known as “codec” can encode or decode AVI files and may contain any other file format including MPEG-4 (MP4), QPEG, MPEG, Realtime, Cinepak, and JPEG.

How AVI Files Work
AVI files store audio and video data for movies by dividing the data into different segments. These segments are known as “hdrl,” “movi,” and “idx1” respectively. The “hdrl” segment contains the parameters of a movie, such as the video’s height, width, and frame rate, allowing the media player to display the video itself. The “movi” segment contains the audio and video files, allowing the user to watch a movie. The “idx1” segment measures the offset of the data segments, allowing users to skip to specific points in a movie.

Applications
Though AVI files have been in use for nearly twenty years, they are still used in a number of applications today. AVI files can behave like a DVD disc or even be contained within a DVD file itself. They are also used to play videos on a computer with the aid of a media player. Although more modern techniques, such as MP4 files, have widely replaced AVI files, AVI files are still used because they can contain subtitles and playback audio and video without delays.

Advantages
AVI files can contain audio, video, subtitle, and menu files, and access them simultaneously. AVI files can also compress audio and video files so that they are smaller than other file formats.

Disadvantages
Other file formats that compress audio and video at much better ratios have replaced the outdated AVI files. Likewise, AVI files do not work with all media players and a codec is sometimes required.