128 lines
4.3 KiB
Python
128 lines
4.3 KiB
Python
import time
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from threading import Timer
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from platypush.backend import Backend
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from platypush.message.event.midi import MidiMessageEvent
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class MidiBackend(Backend):
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"""
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This backend will listen for events from a MIDI device and post a
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MidiMessageEvent whenever a new MIDI event happens.
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Triggers:
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* :class:`platypush.message.event.midi.MidiMessageEvent` when a new MIDI event is received
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Requires:
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* **rtmidi** (``pip install rtmidi``)
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"""
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def __init__(self, device_name=None, port_number=None,
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midi_throttle_time=None, *args, **kwargs):
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"""
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:param device_name: Name of the MIDI device. *N.B.* either
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`device_name` or `port_number` must be set.
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Use :meth:`platypush.plugins.midi.query_ports` to get the
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available ports indices and names
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:type device_name: str
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:param port_number: MIDI port number
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:type port_number: int
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:param midi_throttle_time: If set, the MIDI events will be throttled -
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max one per selected time frame (in seconds). Set this parameter if
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you want to synchronize MIDI events with plugins that normally
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operate with a lower throughput.
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:type midi_throttle_time: int
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"""
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import rtmidi
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super().__init__(*args, **kwargs)
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if (device_name and port_number is not None) or \
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(not device_name and port_number is None):
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raise RuntimeError('Either device_name or port_number (not both) ' +
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'must be set in the MIDI backend configuration')
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self.midi_throttle_time = midi_throttle_time
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self.midi = rtmidi.MidiIn()
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self.last_trigger_event_time = None
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self.midi_flush_timeout = None
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ports = self.midi.get_ports()
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if not ports:
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raise RuntimeError('No MIDI devices available')
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if device_name:
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if device_name not in ports:
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raise RuntimeError('MIDI device "{}" not found'.format(device_name))
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self.port_number = ports.index(device_name)
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self.device_name = device_name
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if port_number:
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if port_number < 0 or port_number >= len(ports):
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raise RuntimeError('MIDI port {} not found')
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self.port_number = port_number
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self.device_name = ports[port_number]
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self.midi.set_callback(self._on_midi_message())
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def _on_midi_message(self):
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def flush_midi_message(message):
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def _f():
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self.logger.info('Flushing throttled MIDI message {} to the bus'.format(message))
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delay = time.time() - self.last_trigger_event_time
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self.bus.post(MidiMessageEvent(message=message, delay=delay))
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return _f
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# noinspection PyUnusedLocal
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def callback(message, data):
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# rtmidi will provide a tuple in the format
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# (midi_message, time_since_last_event)
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delay = message[1]
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message = message[0]
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if self.midi_throttle_time and self.last_trigger_event_time:
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event_delta = time.time() - self.last_trigger_event_time
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if event_delta < self.midi_throttle_time:
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self.logger.debug('Skipping throttled message {}'.format(message))
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if self.midi_flush_timeout:
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self.midi_flush_timeout.cancel()
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self.midi_flush_timeout = Timer(
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self.midi_throttle_time-event_delta,
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flush_midi_message(message))
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self.midi_flush_timeout.start()
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return
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self.last_trigger_event_time = time.time()
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self.bus.post(MidiMessageEvent(message=message, delay=delay))
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return callback
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def run(self):
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super().run()
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self.midi.open_port(self.port_number)
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self.logger.info('Initialized MIDI backend, listening for events on device {}'.
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format(self.device_name))
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while not self.should_stop():
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try:
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time.sleep(1)
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except Exception as e:
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self.logger.exception(e)
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if self.midi:
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self.midi.close_port()
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self.midi = None
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# vim:sw=4:ts=4:et:
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