THIS EXTENSION IS DEPRECATED! USE THE EVENT PORT EXTENSION INSTEAD!
This extension adds a MIDI datatype to the LV2 standard which can be used in input and output ports. You can use it when you write synth plugins so you can read MIDI events from the outside world, or maybe a sequencer plugin that writes MIDI to an output port.
The details are in this header file [dox], which you need to include in your host or plugin if you want to use this extension. The file is licensed under the GNU LGPL, which is the same license as the LV2 header itself, so that should not be an issue.
The official header file only defines the data format that should be used when moving MIDI to and from plugins, it does not contain any functions or macros that help you do it. For that you can use this file [dox], which is a header file that contains some static function definitions that reads and writes MIDI events from and to LV2 MIDI buffers. Note that it is not an official part of the extension, you don't have to use it, but if you don't you will probably want to write something similar yourself. This file is also licensed under the GNU LGPL.