M2V is a video category file format, also called MPEG-2 Video. It supports video with a tighter time constraint and interlaced display. The encoded speed at which data is transmitted may be of the order of 40 Mbps (for storage and transmission). It may be higher for professional use in video production. Large frame sizes do not support HD resolution. MPEG-2 format is compatible with MPEG-1. The MPEG-2 format is used mainly for the consumer level of video broadcasting - for example, DVB. And for storage - for example, DVD. But they are also used for professional applications. Say for storing video in a studio. Files with the extension .m2v are necessary if you are preparing a video for burning to DVD using specialized programs. There will be no sound in such a file. This encoding method also involves the .m2a file, where the sound is stored. Then this pair of files (.m2v and .m2a) will be sent to the authoring program line. The program will output them without recoding in the program stream (MPEG 2 PS). There is one caveat. When the weight of these files is 4.3 GB or more, then you need to transcode this file and reduce the bitrate. So when you create * .m2v, you must first select the correct bitrate.
3GA is a 3GPP audio file created in 1998. It was created by the 3rd Generation Partnership Project. It is used mainly on mobile devices in order to record, play and transmit audio data. 3GPP (3rd Generation Partnership Project) is a consortium that develops specifications for mobile telephony. The format resembles 3GP files, however, it includes only audio data. In most cases, 3GA files are used by mobile phones in order to record and transmit audio data. For example, this is how audio is recorded in Samsung Galaxy phones. The .3GA file extension can be changed to .3GP, which is widespread. Everything is supported by many programs. The 3GA format uses an adaptive coding audio codec with variable speed (AMR, AMR-NB, GSM-AMR). The development of this codec was done in order to compress encoded speech signals using adaptive modulation. In 1999, the 3GPP consortium adopted the Adaptive Variable Rate Coding (AMR) standard. Currently, it is used by GSM and UMTS communication systems. It is this format for speech recording that has found wide application on mobile devices. We note at the same time that it is not possible to play such files very often on certain devices.