Example program that makes a MIDI echo/looper.

simplecoremidi/examples/repeater.py

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+
+from time import time, sleep
+from simplecoremidi import MIDISource, MIDIDestination
+
+LOOP_WAIT = 1.0 / 200  # 200 Hz
+DELAY = 1  # 1 sec
+
+def repeater():
+    dest = MIDIDestination("repeater input")
+    source = MIDISource("repeater output")
+
+    frames = []
+
+    last_frame_time = time()
+    while True:
+        midi_in = dest.recv()
+        if midi_in:
+            #source.send(midi_in)
+            frames.append((last_frame_time + DELAY, midi_in))
+        while frames:
+            midi_out = frames[0]
+            if midi_out[0] < last_frame_time:
+                source.send(midi_out[1])
+                frames.pop(0)
+            else:
+                break
+
+        now = time()
+        wait_time = -1
+        while wait_time <= 0:
+            last_frame_time = last_frame_time + LOOP_WAIT
+            wait_time = last_frame_time - now
+        sleep(wait_time)
+
+if __name__=='__main__':
+    repeater()