Mastroka (also called MKV) is an open-standard multimedia format for HD video format. However, it is not widely supported by media players. You are not able to add video to iTunes. You can not play MKV files on your iPhone, iPad, iPod. MKV is also not supported by Android phones such as Samsung Galaxy, LG, Sony Xperia, HTC, Motorola Moto, etc.
On the other hand mp4 is more popular supported by mobile devices and media player. So a good way is to convert video from mkv to mp4 format. You can follow this video converter tutorialconvert mkv to mp4
The mkv to mp4 tutorial is easy to use and can convert mkv videos to mp4 format. You can also use Asoftech Video Covnerter to convert videos between other formats, such as mov, wmv, asf, avi, mp4, mkv, avchd, etc.
Read more informationHow to convert mkv video for iTunesHow to convert video between different formatsFix unsupported video for Samsung phone/tablet