Files with this extension are linked to the MIDI (Musical Instrument Digital Interface) standard. These are then available in standard MIDI format (SMF). MIDI is a standardized digital interface for musical instruments.
MID files contain data for pitch, duration, stop, and control commands for synthesizers. But they are also used directly to control music studio or stage equipment and then consist only of control commands.
MIDI data is used to control synthesizers and other sound generators. The MID files therefore contain no audio data other than MP3. To listen to the music you need a synthesizer, either as hardware or software. The sound then depends solely on the synthesizer used.
Many musicians use MIDI for composing. With the help of programs called sequencers (eg Ableton, Cubase, FL Studio) several electronic instruments up to the virtual Philharmonic Orchestra can be successively recorded and edited.
Most often resolving problems with opening MID files is very simple. Just install an appropriate program that supports such files. All of the listed programs support MID files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of MID files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate MID files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the QuickTime Player applications is not on the list, select "Browse" option in order to manually locate the directory where QuickTime Player has been installed.
Sometimes problems with opening MID files may not lie with the application itself, but can arise due to other causes, such as: