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.
3G2 is an audio / video format that was developed using the 3rd Generation Partnership Project 2 (3GPP2). The file extension is an improved version of the 3GP format. Today it is already outdated, despite the fact that it was previously updated. As a result of the implementation of the 3rd Generation Partnership Project, standards were developed that relate to methods of transmitting a wide variety of media data. For example, on mobile networks. The development of such standards, in particular, has led to the introduction of the 3G2 format and to the use of various types of media data on the global network for online streaming. This type of file is most often used on mobile phones, as well as on phones that support 3G. 3G2 video files can also be played on many computers. We emphasize that in this case there may be a need for additional applications. The 3G2 format is very similar to the MPEG-4 Part 14 series (MP4) format. However, in comparison with it, the 3G2 format is not so complicated. When you apply this type of file, you need to consider the possibility of reducing the requirements for the width of both the information transfer channel and disk space. So, the format for mobile phones is exactly what you need. 3G2 files have been specifically developed for phones operating in the CDMA standard.