MKV is an open container format for audio and video data created by Russian developers. The name of the format originates from the name of the project - Matroska (Matryoshka) with the addition of the first letter of the word Video. This format is considered an alternative to the much more popular AVI, but has not yet reached such a scale of distribution. MKV files are quite common among owners of fairly old mobile devices with Symbian OS and at the same time among those who prefer to watch video in FullHD, since MKV has good dynamics of transmitting video / audio streams. MKV with a wide range of features, in particular, storing audio tracks in different languages, is easy to edit, there are no freezes in large files.
M4P is an Audio file format developed by Apple Inc. Files with the .m4p extension are audio files that are downloaded from the iTunes Music Store. These are files that are encoded using the AAC method. They are additionally protected by Apple "FairPlay" DRM. The M4P file format is an extended version of storage formats such as MPEG-4 Part 14 or MP4. The format was initially associated with Apple's Protected AAC files. Now, the M4P format uses the FairPlay DRM system, which does not provide the ability to copy data. She also needs to authorize the device using Apple iTunes software. An M4P file is an array of data that is protected by a DRM system. And in order to play the file, some actions are required that are aimed at authorizing the computer in Apple's iTunes system. The M4P format limits the number of computers on which a specific file can be played. This will require registration with Apple iTunes. This will be enough to immediately use five computers. In the event that you need to play the file on more than five computers, you will need another account. In this case, you will need to purchase the song that you selected from a new account. Then access to it on the other five devices will be open.