MKV is an open source container that can contain media data compressed with a use of different codecs. It has a lot of advantages over the legacy AVI container: it can contain audio tracks and subtitles in different languages, that can be switched without stopping the playback, file seek and rewind are very fast. Also the format is easy to edit, that is why audio and video data can be extracted effortlessly.

This format was originally intended for voice compression and is able to change the bit rates of encoded audio data. AMR is actively used for encoding and decoding voice while its being transmitted over network channels. The format allows one to consider network capacity and adapt it to channel loads. Due to this, the voice quality is practically undiminished.