This format(container) for coding animated sequences and sound comes from the company Microsoft. For image coding various types of compression are used, with the basic being the non-compressed frame sequence of up to compression approximating through their effectiveness to the MPEG compression ratio. The advantage of non-compressed AVI files is their very fast creation, for instance in the course of recording from a television card, and subsequent coding into MPEG, of course, if you do not own an HW device able to compress into MPEG in real time. The disadvantage is the relatively large size of this sort of file.