From ecd55f9fec0dda36b28393cdb33c7daa9e551da9 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Fri, 8 May 2020 23:42:30 +0200
Subject: [PATCH] LTC Slave: subscribe to LatencyUpdated signal

This uses a recently introduce Signal instead of the generic
GraphReordered, which was used in the past since it usually
happened after the latency was changed.
---
 libs/ardour/ardour/transport_master.h |  6 +++---
 libs/ardour/ltc_slave.cc              | 24 +++++++++++++++---------
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/libs/ardour/ardour/transport_master.h b/libs/ardour/ardour/transport_master.h
index 902f4f6f72..9e745cbef5 100644
--- a/libs/ardour/ardour/transport_master.h
+++ b/libs/ardour/ardour/transport_master.h
@@ -610,7 +610,7 @@ private:
 	bool detect_ltc_fps (int, bool);
 	bool equal_ltc_sample_time (LTCFrame* a, LTCFrame* b);
 	void resync_xrun ();
-	void resync_latency ();
+	void resync_latency (bool);
 	void parse_timecode_offset ();
 	void parameter_changed (std::string const& p);
 
@@ -635,8 +635,8 @@ private:
 	Timecode::TimecodeFormat a3e_timecode;
 	double                   samples_per_timecode_frame;
 
-	PBD::ScopedConnectionList port_connections;
-	PBD::ScopedConnection     config_connection;
+	PBD::ScopedConnection     port_connection;
+	PBD::ScopedConnectionList session_connections;
 	LatencyRange              ltc_slave_latency;
 };
 
diff --git a/libs/ardour/ltc_slave.cc b/libs/ardour/ltc_slave.cc
index c265835c08..bc0a8fb724 100644
--- a/libs/ardour/ltc_slave.cc
+++ b/libs/ardour/ltc_slave.cc
@@ -66,10 +66,9 @@ LTC_TransportMaster::LTC_TransportMaster (std::string const & name)
 {
 	memset (&prev_frame, 0, sizeof(LTCFrameExt));
 
-	resync_latency();
+	resync_latency (false);
 
-	AudioEngine::instance()->Xrun.connect_same_thread (port_connections, boost::bind (&LTC_TransportMaster::resync_xrun, this));
-	AudioEngine::instance()->GraphReordered.connect_same_thread (port_connections, boost::bind (&LTC_TransportMaster::resync_latency, this));
+	AudioEngine::instance()->Xrun.connect_same_thread (port_connection, boost::bind (&LTC_TransportMaster::resync_xrun, this));
 }
 
 void
@@ -89,7 +88,7 @@ LTC_TransportMaster::create_port ()
 void
 LTC_TransportMaster::set_session (Session *s)
 {
-	config_connection.disconnect ();
+	session_connections.drop_connections();
 	_session = s;
 
 	if (_session) {
@@ -109,14 +108,15 @@ LTC_TransportMaster::set_session (Session *s)
 		parse_timecode_offset();
 		reset (true);
 
-		_session->config.ParameterChanged.connect_same_thread (config_connection, boost::bind (&LTC_TransportMaster::parameter_changed, this, _1));
+		_session->config.ParameterChanged.connect_same_thread (session_connections, boost::bind (&LTC_TransportMaster::parameter_changed, this, _1));
+		_session->LatencyUpdated.connect_same_thread (session_connections, boost::bind (&LTC_TransportMaster::resync_latency, this, _1));
 	}
 }
 
 LTC_TransportMaster::~LTC_TransportMaster()
 {
-	port_connections.drop_connections();
-	config_connection.disconnect();
+	port_connection.disconnect();
+	session_connections.drop_connections();
 
 	if (did_reset_tc_format) {
 		_session->config.set_timecode_format (saved_tc_format);
@@ -185,14 +185,20 @@ LTC_TransportMaster::resync_xrun()
 }
 
 void
-LTC_TransportMaster::resync_latency()
+LTC_TransportMaster::resync_latency (bool playback)
 {
+	if (playback) {
+		return;
+	}
 	DEBUG_TRACE (DEBUG::LTC, "LTC resync_latency()\n");
-	sync_lock_broken = false;
 
+	uint32_t old = ltc_slave_latency.max;
 	if (_port) {
 		_port->get_connected_latency_range (ltc_slave_latency, false);
 	}
+	if (old != ltc_slave_latency.max) {
+		sync_lock_broken = false;
+	}
 }
 
 void