m4v M4V is a file format developed by Apple for the iTunes store's content and is very similar to the MP4 file extension. M4V is supported exclusively by Apple devices. Other video formats like MP4 and MOV can be converted to M4V in order to run on Apple devices. The most common difference between the M4V and MP4 formats is that M4V offers DRM-Copyright Protection which prevents the copyright of media content. To play a DRM-protected M4V file the computer needs authorization by opening the iTunes account used for buying the media file. However, if the files are not protected by DRM, the user can just rename the file extension from M4V to MP4 in order for it to be recognized by non-apple devices.
3gp The 3GP file format and its associated filename extension .3gp is an audio, video, and text container developed by the 3rd generation partnership project. The target market for the 3gp file format is 3G enabled UMTS mobile phones through associated UMTS multimedia services. Though mobile devices operating on high speed networks are the intended hardware associated with playing .3gp files, many PC codec packs exist which grant compatibility for .3gp playback. The format has a basic profile in which files of this format do not reference any external media sources and support for audio, video, and text is limited to a single track.