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.
wav The Waveform Audio file format associated with the .wav filename extension was a format developed through collaboration between Microsoft and IBM. It is an extension of the RIFF and was first released in 1991. It is one of the earliest standards used for encoding audio bit streams on personal computers. It is typically used for storing uncompressed raw audio files on the Microsoft Windows platform, however it enjoys cross platform support on Macintosh and Linux and does have support for compressed audio. Because of the relatively large file sizes of uncompressed .wav files, the WAVE format in unpopular for file distribution over limited bandwidth computer networks including the internet.