diff --git a/libs/ardour/ardour/slave.h b/libs/ardour/ardour/slave.h
index b64ba3f42e..fa75ba17bb 100644
--- a/libs/ardour/ardour/slave.h
+++ b/libs/ardour/ardour/slave.h
@@ -28,6 +28,8 @@
 
 #include "pbd/signals.h"
 
+#include "timecode/time.h"
+
 #include "ardour/types.h"
 #include "midi++/parser.h"
 #include "midi++/types.h"
@@ -223,7 +225,14 @@ struct SafeTime {
 	}
 };
 
-class MTC_Slave : public Slave {
+class TimecodeSlave : public Slave {
+  public:
+    TimecodeSlave () {}
+
+    virtual Timecode::TimecodeFormat apparent_timecode_format() const = 0;
+};
+
+class MTC_Slave : public TimecodeSlave {
   public:
 	MTC_Slave (Session&, MIDI::Port&);
 	~MTC_Slave ();
@@ -240,6 +249,8 @@ class MTC_Slave : public Slave {
 	framecnt_t seekahead_distance() const;
 	bool give_slave_full_control_over_transport_speed() const;
 
+        Timecode::TimecodeFormat apparent_timecode_format() const;
+
   private:
 	Session&    session;
 	MIDI::Port* port;
@@ -298,7 +309,7 @@ class MTC_Slave : public Slave {
 };
 
 #ifdef HAVE_LTC
-class LTC_Slave : public Slave {
+class LTC_Slave : public TimecodeSlave {
   public:
 	LTC_Slave (Session&);
 	~LTC_Slave ();
@@ -313,6 +324,8 @@ class LTC_Slave : public Slave {
 	framecnt_t seekahead_distance() const;
 	bool give_slave_full_control_over_transport_speed() const;
 
+        Timecode::TimecodeFormat apparent_timecode_format() const;
+
   private:
   int parse_ltc(const jack_nframes_t nframes, const jack_default_audio_sample_t * const in, const framecnt_t posinfo);
 	void process_ltc();
diff --git a/libs/ardour/ltc_slave.cc b/libs/ardour/ltc_slave.cc
index cc86189d8c..51fa181414 100644
--- a/libs/ardour/ltc_slave.cc
+++ b/libs/ardour/ltc_slave.cc
@@ -172,4 +172,13 @@ LTC_Slave::speed_and_position (double& speed, framepos_t& pos)
 	speed = ltc_speed;
 
 	monotonic_fcnt += nframes;
+
+	return true;
+}
+
+Timecode::TimecodeFormat
+LTC_Slave::apparent_timecode_format () const
+{
+	/* XXX to be computed, determined from incoming stream */
+	return timecode_30;
 }
diff --git a/libs/ardour/mtc_slave.cc b/libs/ardour/mtc_slave.cc
index 1191a4f0b4..49178614f7 100644
--- a/libs/ardour/mtc_slave.cc
+++ b/libs/ardour/mtc_slave.cc
@@ -615,3 +615,10 @@ MTC_Slave::speed_and_position (double& speed, framepos_t& pos)
 
 	return true;
 }
+
+Timecode::TimecodeFormat
+MTC_Slave::apparent_timecode_format () const
+{
+	/* XXX to be computed, determined from incoming stream */
+	return timecode_30;
+}