Convert mv4 to art

What is the difference between .mv4 and .art?

Description: M4V is a video container that stores audio and video data used for iTunes files. Files of this type may be protected from illegal viewing and copying with Apple FairPlay DRM. In this case audio or video files should be bought in iTunes store. Not protected files can be viewed almost in any modern player because the format is based on MPEG-4 structure.; PFS Art Publisher Image (ART) is a raster graphics file format used for storing digital images. It was developed by Progressive Networks for use in their Progressive FreeStyle Art Publisher software. ART files are compressed using the run-length encoding (RLE) algorithm, which allows them to store large images in a relatively small file size. The ART format supports up to 24-bit color and is often used for storing digital photos and other images.