M4v is a type of video format, which was introduced by Apple Inc, mainly used in iTunes and iPod player.

convert m4v to avi, m4v to mpeg

M4v has two different types: one is unprotected, you can convert to other formats such as VOB, MPG, AVI using this M4V Converter.

The other is protected, such as videos purchased online from iTunes store, you have to convert Drm protected iTunes M4v to unprotected one in order to remove the encryption.