MID is a sound file format developed by the MIDI Manufacturers Association and is a standard extension for MIDI (Musical Instrument Digital Interface) audio files. Using files of the specified format, the encoding into the standard format of most MIDI data is performed. This standard format is used for the interaction of various devices and programs. The exchange of musical information is between instruments, synthesizers and computers. MID files do not contain the musical data itself, but their attributes - for example, information about how long certain notes sound, or about the pitch, tonality.
MP3 is the most common music (sound) file format. This format was developed by Fraunhofer IIS and Thomson. This format for storing and transmitting music (sound) files in digital form uses signal compression technology. That is why, unlike the previously widespread WAV format, MP3 files (full name - MPEG Audio Layer-3) are much smaller in size, and their sound quality is much higher. The MP3 format was one of the first and most successful sound compression methods. One of the important characteristics of this process is the degree of compression, that is, how much data is transferred per unit of time. Standard MP3 encoding is from 64 to 320 kb / s.