After seeing the lovely display on Ian Dickinson's post on the BOGA Facebook page, I decided to try the iPad version of Synthesia - and it is great! It will be my controller of choice from now on! I have both Sweet MIDI and Synthesia on my cheapo first generation iPad, so if I want Playlists/Searching/Transposing I use Sweet MIDI, or Synthesia if I want the pretty Piano Roll display (see picture at the bottom of the page). Its a bonus that once started, switching between the two Apps does NOT require Bluetooth resetting.
I also looked at using it on a PC and my Microsoft Surface tablet, and there are notes about these - also at the bottom of this page.
MIDI Player Software
Transferring MIDI files
The WIDI Master device can be set to ‘central’ or ‘peripheral’, so up to seven organs – or other MIDI devices – using WIDI Masters can be linked together without the need for cables.
Tuning Organ Pipes with Synthesia
Synthesia is actually primarily designed to assist people learning the piano. As spotted by Norman Taylor, this feature can be useful when tuning organ pipes. Selecting Synthesia/Free Play shows the screen with a piano keyboard at the bottom. Tapping the musical instrument icon in the top left corner enables a continuously-playing instrument - one of the organs - to be selected. Then, tapping and holding the appropriate key on the keyboard causes a pipe to sound continuously, enabling its stopper to be adjusted for tuning. Even with a motorised organ, having more than two hands available at this time would be an asset!
Of course a MIDI file with appropriate continuous notes can be used, but the Synthesia method could be an effective alternative.