Add abstract API for latency compensated sends

This is in preparation for MixbusSends that are not derived from
Delivery : IOProcessor.

libs/ardour/ardour/send.h

@@ -37,7 +37,32 @@ class Amp;
 class GainControl;
 class DelayLine;
 
-class LIBARDOUR_API Send : public Delivery
+/** Internal Abstraction for Sends (and MixbusSends) */
+class LIBARDOUR_API LatentSend
+{
+public:
+	LatentSend ();
+	virtual ~LatentSend() {}
+
+	samplecnt_t get_delay_in () const { return _delay_in; }
+	samplecnt_t get_delay_out () const { return _delay_out; }
+
+	/* should only be called by Route::update_signal_latency */
+	virtual void set_delay_in (samplecnt_t) = 0;
+
+	/* should only be called by InternalReturn::set_playback_offset
+	 * (via Route::update_signal_latency)
+	 */
+	virtual void set_delay_out (samplecnt_t, size_t bus = 0) = 0;
+
+	static PBD::Signal0<void> ChangedLatency;
+
+protected:
+	samplecnt_t _delay_in;
+	samplecnt_t _delay_out;
+};
+
+class LIBARDOUR_API Send : public Delivery, public LatentSend
 {
 public:
 	Send (Session&, boost::shared_ptr<Pannable> pannable, boost::shared_ptr<MuteMaster>, Delivery::Role r = Delivery::Send, bool ignore_bitslot = false);
@@ -69,14 +94,12 @@ public:
 	bool configure_io (ChanCount in, ChanCount out);
 
 	/* latency compensation */
-	void set_delay_in (samplecnt_t); // should only be called by Route::update_signal_latency
-	void set_delay_out (samplecnt_t);  // should only be called by InternalReturn::set_playback_offset (via Route::update_signal_latency)
+	void set_delay_in (samplecnt_t);
+	void set_delay_out (samplecnt_t, size_t bus = 0);
 	samplecnt_t get_delay_in () const { return _delay_in; }
 	samplecnt_t get_delay_out () const { return _delay_out; }
 	samplecnt_t signal_latency () const;
 
-	static PBD::Signal0<void> ChangedLatency;
-
 	void activate ();
 	void deactivate ();
 
@@ -106,8 +129,6 @@ private:
 	int set_state_2X (XMLNode const &, int);
 
 	uint32_t    _bitslot;
-	samplecnt_t _delay_in;
-	samplecnt_t _delay_out;
 	bool        _remove_on_disconnect;
 };
 

libs/ardour/route.cc

@@ -4115,7 +4115,7 @@ Route::update_signal_latency (bool apply_to_delayline)
 	samplecnt_t l_in  = 0;
 	samplecnt_t l_out = _output->effective_latency ();
 	for (ProcessorList::reverse_iterator i = _processors.rbegin(); i != _processors.rend(); ++i) {
-		if (boost::shared_ptr<Send> snd = boost::dynamic_pointer_cast<Send> (*i)) {
+		if (boost::shared_ptr<LatentSend> snd = boost::dynamic_pointer_cast<LatentSend> (*i)) {
 			snd->set_delay_in (l_out + _output->latency());
 		}
 
@@ -4155,6 +4155,7 @@ Route::update_signal_latency (bool apply_to_delayline)
 				snd->output ()->set_private_port_latencies (capt_lat_in + l_in, false);
 				/* take send-target's playback latency into account */
 				snd->set_delay_out (snd->output ()->connected_latency (true));
+				/* InternalReturn::set_playback_offset() below, also calls set_delay_out() */
 			}
 		}
 

libs/ardour/send.cc

@@ -49,7 +49,13 @@ using namespace ARDOUR;
 using namespace PBD;
 using namespace std;
 
-PBD::Signal0<void> Send::ChangedLatency;
+PBD::Signal0<void> LatentSend::ChangedLatency;
+
+LatentSend::LatentSend ()
+		: _delay_in (0)
+		, _delay_out (0)
+{
+}
 
 string
 Send::name_and_id_new_send (Session& s, Role r, uint32_t& bitslot, bool ignore_bitslot)
@@ -83,8 +89,6 @@ Send::name_and_id_new_send (Session& s, Role r, uint32_t& bitslot, bool ignore_b
 Send::Send (Session& s, boost::shared_ptr<Pannable> p, boost::shared_ptr<MuteMaster> mm, Role r, bool ignore_bitslot)
 	: Delivery (s, p, mm, name_and_id_new_send (s, r, _bitslot, ignore_bitslot), r)
 	, _metering (false)
-	, _delay_in (0)
-	, _delay_out (0)
 	, _remove_on_disconnect (false)
 {
 	if (_role == Listen) {
@@ -198,7 +202,7 @@ Send::set_delay_in (samplecnt_t delay)
 }
 
 void
-Send::set_delay_out (samplecnt_t delay)
+Send::set_delay_out (samplecnt_t delay, size_t /*bus*/)
 {
 	if (_delay_out == delay) {
 		return;

libs/ardour/session.cc

@@ -460,7 +460,7 @@ Session::Session (AudioEngine &eng,
 	StartTimeChanged.connect_same_thread (*this, boost::bind (&Session::start_time_changed, this, _1));
 	EndTimeChanged.connect_same_thread (*this, boost::bind (&Session::end_time_changed, this, _1));
 
-	Send::ChangedLatency.connect_same_thread (*this, boost::bind (&Session::send_latency_compensation_change, this));
+	LatentSend::ChangedLatency.connect_same_thread (*this, boost::bind (&Session::send_latency_compensation_change, this));
 
 	emit_thread_start ();
 	auto_connect_thread_start ();