Document MIDI inputs for Futatabi.

diff --git a/futatabi.rst b/futatabi.rst
index 4de096e08943803e42571395020af08ae656584c..938532542fd2eb1c08cc78e30e40f5f3411702ca 100644 (file)
--- a/futatabi.rst
+++ b/futatabi.rst
@@ -85,7 +85,7 @@ Basic UI operations
 
 Nageru can be operated using either the keyboard and mouse, or using a MIDI
 controller with some help of the mouse. In this section, we will be discussing
-the keyboard and mouse only; see :ref:`midi` for details on using MIDI
+the keyboard and mouse only; see :ref:`midi-futatabi` for details on using MIDI
 controllers.
 
 A clip in the clip list consists simply of an in and an out point; it represents
@@ -280,11 +280,35 @@ not marked as metadata due to FFmpeg limitations, and as such will show up
 raw in subtitle-enabled players.
 
 
-.. _midi:
+.. _midi-futatabi:
 
 Using MIDI controllers
 ----------------------
 
+This section assumes you have already read the section about
+`MIDI controllers in Nageru <audio.html#midi-controllers>`__. MIDI controllers
+in Futatabi are fairly similar, but there are also some important differences,
+since they control replay and not audio:
+
+  * There is no concept of a bus (there is only one video output channel).
+    Thus, the concept of guessing also is obsolete.
+  * Since there are no buses, there are also usually plenty of buttons
+    and controls, rendering the bank concept less useful. It *is* supported,
+    but activity highlights (to show which bank is active) are not.
+  * Finally, outputs (controller lights and button lights) frequently have
+    more than one state depending on the velocity sent, e.g. 1 for on and 2 for
+    blinking. Thus, the Futatabi MIDI mapping editor allows you to change the
+    note velocities from the default 1.
+
+Futatabi has been tested with the `Behringer CMD PL-1 <https://www.musictribe.com/Categories/Behringer/Computer-Audio/DJ-Controllers/CMD-PL-1/p/P0AJF>`;
+it is not originally designed for slow motion, but provides everything you
+need (a jog wheel, a slider that works as a T bar for master speed, and plenty
+of buttons) at a fraction of the price of a “real” slow motion remote.
+A sample MIDI mapping is included with Futatabi.
+
+Futatabi currently does not support classic RS-422 controllers, only MIDI
+controllers.
+
 
 Monitoring
 ----------