As mentioned elsewhere, Box Of Stops uses a small but crucial [[Python]] script to achieve its real-time playback. Most customization work with Box Of Stops can be achieved with [[Trigger|triggers]] or [[Gpio button|GPIO buttons]], but occasionally there is a requirement to inject a note into the live playing engine. This can be achieved with something called an Extras script. This is typically a short Python script that will be imported into the main Python script that Box Of Stops uses. Please see <googa>https://github.com/boxofstops/boxofstops-examples|https://github.com/boxofstops/boxofstops-examples</googa> for the latest examples of Extras scripts. == Using == To add an Extras script to Box Of Stops, please look for the <tt>~/boxofstops/.python</tt> directory (see [[Directories]] for more information). By default the Extras script is called <tt>extras.py</tt> in this directory. Just add this file and [[Starting|restart]] - Box Of Stops will auto-detect the script and call it while initializing. == Renaming the script == It is possible to use a script with a different name than <tt>extras.py</tt>. Please look for the <tt>python.extras.script</tt> property in the [[Application properties]] file. == Internal API == There is a small internal API available to call back to, to register a device and inject notes or other events into the running Box Of Stops script. * <tt>boxofstops.add_device_channel(device_name,channel)</tt> - register a new input device and channel to play to a [[Bank]] in Box Of Stops.<br/>The Bank will see this as new Midi input, but the point of the Extras script is to simulate a Midi input, while generating notes and events from an alternative source.* <tt>boxofstops.midi_in_event(device_name,msg)</tt> - inject a note (or other MIDI event) into the Box Of Stops playing engine.<br/>This note_on/note_off will be played on the appropriate [[Bank]] for the <tt>device_name</tt> and the <tt>channel</tt> in the message.<br/>The <tt>msg</tt> is a <googa>https://mido.readthedocs.io/en/latest/messages.html|MIDO Message</googa>. Again please see the <googa>https://github.com/boxofstops/boxofstops-examples|examples code</googa> for examples of this being used. boxofstops.midi_in_event(''Under construction'device_name''',mido.Message(''''note_on'''', note='''60''', channel='''0''', velocity='''80''')) boxofstops.midi_in_event('''device_name''',mido.Message(''''note_off'''', note='''60''', channel='''0''', velocity='''80''')) == Debugging == Note that any output from the Extras script is automatically sent to the [[Logging output]].* If no script is found, the logging output shows: <tt><<< Not loading extras.py</tt>* If the script is found, typically the logging output shows any print statement at the top of the script. E.g. : <tt><<< In extras</tt>