manual/include/midi-overview.html

<p>
  MIDI (or Musical Instrument Digital Interface) is a method of representing
  musical concepts in a form suitable for use in computers. MIDI defines 16
  different <dfn>channels</dfn>, along which messages are passed to instruments
  or synthesizers that understand the MIDI protocol; notes are played by
  sending appropriately crafted <dfn>NoteOn</dfn> messages that are followed
  by <dfn>NoteOff</dfn> messages. MIDI channels can be manipulated with
  special <dfn>controller</dfn> messages to alter the pitch of instruments, or
  their volume or timbre, and they can also tell the instrument or synthesizer
  what sound to play using <dfn>Program Change</dfn> and <dfn>Bank Select</dfn>
  messages.
</p>

<p class="note">
  Typically Program Change and Bank Select messages are collectively referred to by the singular term <dfn>Patch Change</dfn>.
</p>

<h2>Key features of Ardour MIDI handling</h2>

<ul>
  <li>
    MIDI, just like audio, exists in regions. MIDI regions behave like audio
    regions: they can be moved, trimmed, copied (cloned), or deleted. Ardour
    allows either editing MIDI (or audio) regions, or MIDI region content (the
    notes), but never both at the same time. The <kbd>e</kbd> key
    (by default) sets <a href="@@toolbox#edit-internal">Internal Edit</a> Mode,
    which allows the editing of MIDI data in a given region.
  </li>
  <li>
    All MIDI I/O is handled by the audio/MIDI backend was chosen when
    starting Ardour. In general, all backends provide sample accurate
    timing and maximal efficiency when communicating with external
    software synthesizers.
  </li>
  <li>
    Every MIDI track has its own input port; it may have an arbitrary
    combination of audio and MIDI outputs, depending on the signal
    processing in the track; the full flexibility of Ardour patching
    &amp; connectivity is present for MIDI just as it is for audio.
  </li>
  <li>
    Full automation for MIDI tracks, integrated with the handling of all MIDI
    <abbr title="Continuous Controller">CC</abbr> data for each track.
  </li>
  <li>
    Controllers (CC data) can be set to discrete or continuous modes; the
    latter will linearly interpolate between control points and send additional
    data.
  </li>
</ul>

<h2>Notable differences compared to other DAWs and sequencers</h2>

<ul>
  <li>
    Fader (volume) control currently operates on transmitted MIDI data, not by
    sending CC #7.
  </li>
  <li>
    All note/data editing is per-region. There are no cross-region operations at
    this time.
  </li>
  <li>
    By default, copying a MIDI region creates a <dfn>deep link</dfn>&mdash;both
    regions share the same data source, and edits to the contents of one will
    affect the other. Breaking this link is done by selecting <kbd
    class="menu">MIDI &gt; Unlink from other copies</kbd> from the region
    context menu, after which the selected region(s) will have their own copies
    of <em>only</em> the data that they visually display on screen. The region
    will no longer be trimmable back to its original length after an Unlink
    operation, and the operation cannot be undone.
  </li>
</ul>