Is it possible to some start bristol and load it with one or more synth "definitions" and then send midi to bristol (key events, program change, etc), without using brighton?
IIRC, it isn't possible to do this..
No, not possible. Bristol does nothing until directed to start an emulator by the GUI. Imagine trying to play a hammond that has no drawbars - you cannot pull out stops to get harmonics.
As a side note, if you use program change from a midi controller the program change goes to the engine if you 'aconnect' the controller to the engine. Nothing happens. You have to get the midi message to the GUI as the GUI has the responsibility to load and save memories - when the GUI gets the message it opens the memory location and sends the contents to the GUI window which subsequently programs the emulator in the engine.
This is one of the reasons that for seamless distributed functionality I need to distribute MIDI messages from the engine to the GUI - you probably only have your master controllers connected to one system so the application needs to do the distribution.
Could be useful to start with brighton but without graphics.
I thinking about using some embedded board like the beagle board
but not necessarily with a display (or a standard PC-like display).
This is possible already, several options depending on what you want to do:
This will just start the engine and it will wait for a GUI to connect over TCP.
startBristol -window -cli
This will start the engine and UI but will have a command line interface rather than graphical user interface. You can actually build bristol without the X11 header or libraries and only have a CLI.