search

spatialaudio / jackclient-python

🂻 JACK Audio Connection Kit (JACK) Client for Python :snake:
https://jackclient-python.readthedocs.io/
MIT License
132 stars 26 forks source link

How to send sysex messages? #48

Closed ViktorNova closed 6 years ago

ViktorNova commented 6 years ago

I am trying to use jackclient-python to send sysex messages, and it was unclear from the documentation how to do this. Can you give me a simple example?

The sysex message I'm trying to send is F0 7F 7F 06 02 F7 (MMC play)

Thanks! I love this project!

mgeier commented 6 years ago

To be completely honest, I've never used sysex messages.

Did you have a look at those:

http://jackclient-python.readthedocs.io/en/0.4.4/#jack.OwnMidiPort http://jackclient-python.readthedocs.io/en/0.4.4/#jack.OwnMidiPort.clear_buffer http://jackclient-python.readthedocs.io/en/0.4.4/#jack.OwnMidiPort.write_midi_event

See also #47, for some hints.

It would indeed be nice to add some more MIDI examples, I just didn't have any more ideas for simple and instructive examples (that work without having specific hardware).

If you have some concrete ideas for examples, please tell me and I can try to create some more.

MaurizioB commented 6 years ago

It's almost like any other midi event:

outport.clear_buffer()
outport.write_midi_event(0, [0xF0, 0x7F, 0x7F, 0x06, 0x02, 0xF7])

where the first argument is the time (in samples) relative to the beginning of the current audio block, which should be fine to set to 0 if you plan on sending that message only.

mgeier commented 6 years ago

@MaurizioB Thanks for the example. Shouldn't clear_buffer() come first?

MaurizioB commented 6 years ago

@mgeier well, you are right :-) It has been a lot since I used it, I just did a test on the python console, which obviously behaves in a different way than an event loop.

ViktorNova commented 6 years ago

Thanks so much guys! Yeah I couldn't quite make sense of the syntax from the documentation but this seems very straightforward for sysex. What would be the proper way to send a CC? Like say I wanted to send a value of 2 on CC#3? I still don't quite understand how to format it

mgeier commented 6 years ago

@ViktorNova You just have to provide the raw bytes as defined by the MIDI standard. You can either do this as a list of int values, or you can specify a bytes object.

I guess you could find the description of the relevant bytes in the MIDI specification, but you can also make a quick web search, to find e.g. that: http://www.ccarh.org/courses/253/handout/controllers/.

I have no clue if that's correct, but I guess that's the byte sequence you want (where channel is the channel number):

[0xB0 | channel, 3, 2]
ViktorNova commented 6 years ago

Thank you for the explanation, I think I can figure it out from here!