MPC is one of the files of the Audio category. This unlicensed file format is intended to store audio information. The MPC format (i.e. Musepack Compressed Audio File) was created by Musepack. Musepack is a lossy compression scheme developed by German programmer Andree Buschmann. He started creating the codec in 1997. At that time he had the name MP +. The developer was not satisfied with the existing quality of MP3 coding. The algorithm is based on MP2 (MPEG-1 Layer 2), where there are 32 frequency bands, but with significant improvements. Over the past years, it has undergone revision and has become much better. It is currently at a more advanced stage, which contains highly optimized and unpatented source code. The MPC encoding quality at high bitrates (160 Kbps and more) is much higher than the quality that MP3 provides. During coding, a different psychoacoustic compression algorithm is used. In MPC, frequencies that ignore MP3 encoders do not disappear. The specificity of MPC is the fine tuning of psychoacoustics. This provides the ability to operate with pure VBR encoding (variable bit rate encoding). The main task of Musepack is to obtain the highest transparency of sound.
RM is a video file format developed by RealNetworks. It uses the RealPlayer player, that is, a program for streaming audio and video files. The format contains audio and video data or links to streaming, which can be played back as it downloads. The RealMedia Player program was in great demand when they connected to the Internet using a modem, and when there was practically no broadband access to the global network. The large compression ratio of the format provided the opportunity to carry out online transmission of video and audio data. The quality of the output file, as a rule, was low. Today, such files are often used in order to broadcast Internet radio and Internet video. In the .RM format, music and video are found on the global network or on Western cable channels, on Internet radio stations. Support for this format is carried out by such mobile phones and smartphones as Nokia, Ericsson, Sony, iPhone, as well as mobile devices that operate on the Google Android operating system. Files with the extension .RM are compressed using proprietary codecs RealVideo and RealAudio. Individual Real Media files can be played using a VLC media player that partially supports RM files.