These are the favorite instance of the Resource Interchange File Format (RIFF), which divides the file's information higher into information deflects known as "chunks". To each one "chunk" is identified by the FourCC tag. An .avi file requires a form of one chunk around an RIFF formatted file, which is so subdivided into 2 required "chunks" & of these optional "chunk".

A foremost sub-chunk is identified per "hdrl" tag. This chunk is a file header & contains metadata all about a streaming like a breadth, height & the total of frames. A 2nd sub-chunk is identified per "movi" tag. This chunk contains a actual audio/visual information that is a .avi flick. A third optional sub-chunk is identified per "idxl" tag & indexes a location of a information chunks in the file.

By way of a RIFF format, the audio/visual information contained in the "movi" chunk may be encoded or even decoded by the software program module known as the codec. A codec translates between raw information & a formatting within a chunk. An .avi file can so carry audio/visual information within a chunks in nigh any compression scheme, including: Good Frames (Uncompressed), Intel Real Period Streaming video, Indeo, Cinepak, Motion JPEG, Editable MPEG, VDOWave, ClearVideo / RealVideo, QPEG, MPEG-4, XviD, DivX and others.