diff --git a/scripts/led-matrix-viz.py b/scripts/led-matrix-viz.py
index df08159..afeaf21 100644
--- a/scripts/led-matrix-viz.py
+++ b/scripts/led-matrix-viz.py
@@ -137,6 +137,7 @@ def main():
                     if changed:
                         changed_true += 1
                         events_processed += 1
+                        print(f"[viz] note {note} {'on' if vel > 0 else 'off'} events={events_processed}", flush=True)
                         params = render(active_notes)
                         if params != last_sent_params:
                             msg_id = (msg_id + 1) % 65535