M4V video file format is developed by Apple Inc. M4V is extremely similar to the common MP4 format, but might be copy-protected using Apple's FairPlay DRM copyright protection which requires purchase from Apple iTunes store. M4V format is used for the videos downloaded from Apple iTunes store like movies, TV shows and music videos which are encoded under the official DRM copy protection. The M4V file format is based on the MPEG-4 AVC (Advanced Video Coding) video compression and is commonly used by iPhone, iPod, PlayStation Portable, etc. It is used as the default video conversion format for Air Video Server dwelled on Mac. To play a protected M4V file, the system has to be authorized with the authorized iTunes account through which the video was purchased. Unprotected M4V can be renamed to the common extension “.mp4” after which it can be played by other video players.