From 47eeb6dd983965eea0906b27851f4b74a7ece60f Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Thu, 6 Nov 2025 09:18:01 -0700
Subject: [PATCH] make Route::input_change_handler() virtual and use it in
 MidiTrack to notice incoming notes

---
 libs/ardour/ardour/midi_port.h  |  3 +++
 libs/ardour/ardour/midi_track.h |  9 ++++++++-
 libs/ardour/ardour/route.h      |  3 ++-
 libs/ardour/midi_port.cc        |  8 ++++++++
 libs/ardour/midi_track.cc       | 22 ++++++++++++++++++++++
 5 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/libs/ardour/ardour/midi_port.h b/libs/ardour/ardour/midi_port.h
index 47017dddc1..e66272285e 100644
--- a/libs/ardour/ardour/midi_port.h
+++ b/libs/ardour/ardour/midi_port.h
@@ -68,6 +68,9 @@ class LIBARDOUR_API MidiPort : public Port {
 
 	void read_and_parse_entire_midi_buffer_with_no_speed_adjustment (pframes_t nframes, MIDI::Parser& parser, samplepos_t now);
 
+	PBD::Signal<void(int)> NoteOn;
+	PBD::Signal<void(int)> NoteOff;
+
 protected:
 	friend class PortManager;
 
diff --git a/libs/ardour/ardour/midi_track.h b/libs/ardour/ardour/midi_track.h
index eeea1ab190..bfbdf8a35c 100644
--- a/libs/ardour/ardour/midi_track.h
+++ b/libs/ardour/ardour/midi_track.h
@@ -142,6 +142,8 @@ public:
 	void realtime_handle_transport_stopped ();
 	void region_edited (std::shared_ptr<Region>);
 
+	int last_seen_external_midi_note () const { return _last_seen_external_midi_note; }
+
 protected:
 
 	XMLNode& state (bool save_template) const;
@@ -152,6 +154,8 @@ protected:
 	void snapshot_out_of_band_data (samplecnt_t nframes);
 	void write_out_of_band_data (BufferSet& bufs, samplecnt_t /* nframes */) const;
 
+	void input_change_handler (IOChange, void *src);
+
 
 private:
 	MidiRingBuffer<samplepos_t> _immediate_events;
@@ -165,6 +169,7 @@ private:
 	bool                        _restore_pgm_on_load;
 	MidiChannelFilter           _playback_filter;
 	MidiChannelFilter           _capture_filter;
+	int                         _last_seen_external_midi_note;
 
 	std::shared_ptr<VelocityControl>  _velocity_control;
 
@@ -185,7 +190,9 @@ private:
 
 	void playlist_contents_changed ();
 	PBD::ScopedConnection playlist_content_change_connection;
+
+	PBD::ScopedConnectionList note_connections;
+	void note_on_handler (int);
 };
 
 } /* namespace ARDOUR*/
-
diff --git a/libs/ardour/ardour/route.h b/libs/ardour/ardour/route.h
index b451d83801..07a9547f38 100644
--- a/libs/ardour/ardour/route.h
+++ b/libs/ardour/ardour/route.h
@@ -710,6 +710,8 @@ protected:
 
 	SlavableAutomationControlList slavables () const;
 
+	virtual void input_change_handler (IOChange, void *src);
+
 private:
 	/* no copy construction */
 	Route (Route const &);
@@ -717,7 +719,6 @@ private:
 	int set_state_2X (const XMLNode&, int);
 	void set_processor_state_2X (XMLNodeList const &, int);
 
-	void input_change_handler (IOChange, void *src);
 	void output_change_handler (IOChange, void *src);
 	void sidechain_change_handler (IOChange, void *src);
 
diff --git a/libs/ardour/midi_port.cc b/libs/ardour/midi_port.cc
index ed93667b75..00d20dffa0 100644
--- a/libs/ardour/midi_port.cc
+++ b/libs/ardour/midi_port.cc
@@ -152,6 +152,14 @@ MidiPort::get_midi_buffer (pframes_t nframes)
 
 			timestamp -= _global_port_buffer_offset;
 
+			if (size == 3) {
+				if (((buf[0] & 0xF0) == 0x90) && (buf[2] != 0)) {
+					NoteOn (buf[1]);
+				} else if (((buf[0] & 0xF0) == 0x80) || (((buf[0] & 0xF0) == 0x90) && (buf[2] == 0))) {
+					NoteOff (buf[1]);
+				}
+			}
+
 			if ((buf[0] & 0xF0) == 0x90 && buf[2] == 0) {
 				/* normalize note on with velocity 0 to proper note off */
 				uint8_t ev[3];
diff --git a/libs/ardour/midi_track.cc b/libs/ardour/midi_track.cc
index 4a793c33d0..7b00509417 100644
--- a/libs/ardour/midi_track.cc
+++ b/libs/ardour/midi_track.cc
@@ -90,6 +90,7 @@ MidiTrack::MidiTrack (Session& sess, string name, TrackMode mode)
 	, _step_editing (false)
 	, _input_active (true)
 	, _restore_pgm_on_load (true)
+	, _last_seen_external_midi_note (-1)
 {
 	_session.SessionLoaded.connect_same_thread (*this, std::bind (&MidiTrack::restore_controls, this));
 
@@ -979,3 +980,24 @@ MidiTrack::playlist_contents_changed ()
 
 {
 }
+
+void
+MidiTrack::input_change_handler (IOChange change, void *src)
+{
+	note_connections.drop_connections ();
+
+	for (auto const & p : *_input->ports()) {
+		std::shared_ptr<MidiPort> mp = std::dynamic_pointer_cast<MidiPort> (p);
+		if (mp) {
+			mp->NoteOn.connect_same_thread (note_connections, std::bind (&MidiTrack::note_on_handler, this, _1));
+		}
+	}
+
+	Track::input_change_handler (change, src);
+}
+
+void
+MidiTrack::note_on_handler (int notenum)
+{
+	_last_seen_external_midi_note = notenum;
+}