Revert "add an Amp to Delivery, remove it from Send, make use of this in various ::run() methods"

This reverts commit 601a34521c2ce1d0167ed2f3c66f2fa6eeeb6b8e.

6 files changed, 45 insertions, 85 deletions

diff --git a/libs/ardour/amp.cc b/libs/ardour/amp.cc
index b7e639b9f5..880fe2575e 100644
--- a/libs/ardour/amp.cc
+++ b/libs/ardour/amp.cc
@@ -133,19 +133,9 @@ Amp::run (BufferSet& bufs, framepos_t /*start_frame*/, framepos_t /*end_frame*/,
 
 				_current_gain = Amp::apply_gain (bufs, _session.nominal_frame_rate(), nframes, _current_gain, dg, _midi_amp);
 
-			} else if (_current_gain == GAIN_COEFF_ZERO) {
-
-				/* gain has not changed, and is zero. small
-				 * optimization here.
-				 */
-
-				bufs.silence (nframes, 0);
-
 			} else if (_current_gain != GAIN_COEFF_UNITY) {
 
-				/* gain has not changed, but its non-unity and
-				 * isn't zero, so we have to do something
-				 */
+				/* gain has not changed, but its non-unity */
 
 				if (_midi_amp) {
 					/* don't Trim midi velocity -- only relevant for Midi on Audio tracks */
diff --git a/libs/ardour/ardour/delivery.h b/libs/ardour/ardour/delivery.h
index 1b8ff3f87a..e19eef719f 100644
--- a/libs/ardour/ardour/delivery.h
+++ b/libs/ardour/ardour/delivery.h
@@ -34,7 +34,6 @@ class MuteMaster;
 class PannerShell;
 class Panner;
 class Pannable;
-class Amp;
 
 class LIBARDOUR_API Delivery : public IOProcessor
 {
@@ -68,8 +67,6 @@ public:
 	bool set_name (const std::string& name);
 	std::string display_name() const;
 
-	boost::shared_ptr<Amp> amp() const { return _amp; }
-
 	Role role() const { return _role; }
 	bool can_support_io_configuration (const ChanCount& in, ChanCount& out);
 	bool configure_io (ChanCount in, ChanCount out);
@@ -109,8 +106,8 @@ public:
   protected:
 	Role        _role;
 	BufferSet*  _output_buffers;
+	gain_t      _current_gain;
 	boost::shared_ptr<PannerShell> _panshell;
-	boost::shared_ptr<Amp> _amp;
 
 	gain_t target_gain ();
 
diff --git a/libs/ardour/ardour/send.h b/libs/ardour/ardour/send.h
index df9afad55c..17343bff96 100644
--- a/libs/ardour/ardour/send.h
+++ b/libs/ardour/ardour/send.h
@@ -43,6 +43,7 @@ class LIBARDOUR_API Send : public Delivery
 
 	bool display_to_user() const;
 
+	boost::shared_ptr<Amp> amp() const { return _amp; }
 	boost::shared_ptr<PeakMeter> meter() const { return _meter; }
 
 	bool metering() const { return _metering; }
@@ -77,6 +78,7 @@ class LIBARDOUR_API Send : public Delivery
 
   protected:
 	bool _metering;
+	boost::shared_ptr<Amp> _amp;
 	boost::shared_ptr<PeakMeter> _meter;
 	boost::shared_ptr<DelayLine> _delayline;
 
diff --git a/libs/ardour/delivery.cc b/libs/ardour/delivery.cc
index 5a4fbd3e1d..1b8a8c5948 100644
--- a/libs/ardour/delivery.cc
+++ b/libs/ardour/delivery.cc
@@ -52,7 +52,7 @@ Delivery::Delivery (Session& s, boost::shared_ptr<IO> io, boost::shared_ptr<Pann
 	: IOProcessor(s, boost::shared_ptr<IO>(), (role_requires_output_ports (r) ? io : boost::shared_ptr<IO>()), name)
 	, _role (r)
 	, _output_buffers (new BufferSet())
-	, _amp (new Amp (s))
+	, _current_gain (GAIN_COEFF_UNITY)
 	, _no_outs_cuz_we_no_monitor (false)
 	, _mute_master (mm)
 	, _no_panner_reset (false)
@@ -68,8 +68,6 @@ Delivery::Delivery (Session& s, boost::shared_ptr<IO> io, boost::shared_ptr<Pann
 	if (_output) {
 		_output->changed.connect_same_thread (*this, boost::bind (&Delivery::output_changed, this, _1, _2));
 	}
-
-	_amp->activate ();
 }
 
 /* deliver to a new IO object */
@@ -78,7 +76,7 @@ Delivery::Delivery (Session& s, boost::shared_ptr<Pannable> pannable, boost::sha
 	: IOProcessor(s, false, (role_requires_output_ports (r) ? true : false), name, "", DataType::AUDIO, (r == Send))
 	, _role (r)
 	, _output_buffers (new BufferSet())
-	, _amp (new Amp (s))
+	, _current_gain (GAIN_COEFF_UNITY)
 	, _no_outs_cuz_we_no_monitor (false)
 	, _mute_master (mm)
 	, _no_panner_reset (false)
@@ -94,17 +92,16 @@ Delivery::Delivery (Session& s, boost::shared_ptr<Pannable> pannable, boost::sha
 	if (_output) {
 		_output->changed.connect_same_thread (*this, boost::bind (&Delivery::output_changed, this, _1, _2));
 	}
-
-	_amp->activate ();
 }
 
+
 Delivery::~Delivery()
 {
-	DEBUG_TRACE (DEBUG::Destruction, string_compose ("delivery %1 destructor\n", _name));
+	DEBUG_TRACE (DEBUG::Destruction, string_compose ("delivery %1 destructor\n", _name));	
 
 	/* this object should vanish from any signal callback lists
 	   that it is on before we get any further. The full qualification
-	   of the method name is not necessary, but is here to make it
+	   of the method name is not necessary, but is here to make it 
 	   clear that this call is about signals, not data flow connections.
 	*/
 
@@ -238,7 +235,6 @@ Delivery::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame, pf
 
 	PortSet& ports (_output->ports());
 	gain_t tgain;
-	bool need_amp = true;
 
 	if (_output->n_ports ().get (_output->default_type()) == 0) {
 		goto out;
@@ -263,59 +259,28 @@ Delivery::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame, pf
 
 	tgain = target_gain ();
 
-	if (tgain < GAIN_COEFF_SMALL && _amp->gain() < GAIN_COEFF_SMALL) {
-
-		/* special case (but very common) fast path:
-		 *
-		 * if we are supposed to be silent, and we were already silent,
-		 * then short-circuit the computation in Amp and just put silence into
-		 * our output(s)
-		 */
-
-		_output->silence (nframes);
-
-		if (!result_required) {
-			/* if !result_required, then the buffers won't actually
-			 * be used. This means we don't actually need to silence
-			 * them, because we've already filled the output ports
-			 * with silence.
-			 *
-			 * but we just noted that result_required is true,
-			 * and so we do need to run the amp to ensure
-			 * that the buffers are silenced.
-			 */
-			need_amp = false;
-		}
-	}
-
-	if (need_amp) {
-
-		bufs.set_count (output_buffers().count ());
+	if (tgain != _current_gain) {
+		/* target gain has changed */
 
-		if (_role != Main) {
+		_current_gain = Amp::apply_gain (bufs, _session.nominal_frame_rate(), nframes, _current_gain, tgain);
 
-			/* inserts, external and internal sends have
-			 * automatable gain and the Amp::run() method has
-			 * already been executed by the time we get here.
-			 *
-			 * XXX we do not expose the automatable gain for
-			 * Inserts as of September 2015.
-			 */
+	} else if (tgain < GAIN_COEFF_SMALL) {
 
-		} else {
-
-			/* main outs have no automatable gain, the amp is just
-			 * used for ramping gain changes caused by monitoring
-			 * state changes.
-			 */
-
-			_amp->set_gain (tgain, this);
-			_amp->run (bufs, 0, 0, nframes, false);
+		/* we were quiet last time, and we're still supposed to be quiet.
+		   Silence the outputs, and make sure the buffers are quiet too,
+		*/
 
+		_output->silence (nframes);
+		if (result_required) {
+			bufs.set_count (output_buffers().count ());
+			Amp::apply_simple_gain (bufs, nframes, GAIN_COEFF_ZERO);
 		}
-
-	} else {
 		goto out;
+
+	} else if (tgain != GAIN_COEFF_UNITY) {
+
+		/* target gain has not changed, but is not unity */
+		Amp::apply_simple_gain (bufs, nframes, tgain);
 	}
 
         // Speed quietning
@@ -429,7 +394,7 @@ Delivery::pan_outs () const
 {
 	if (_output) {
 		return _output->n_ports().n_audio();
-	}
+	} 
 
 	return _configured_output.n_audio();
 }
@@ -497,7 +462,7 @@ Delivery::flush_buffers (framecnt_t nframes)
 	if (!_output) {
 		return;
 	}
-
+	
 	PortSet& ports (_output->ports());
 
 	for (PortSet::iterator i = ports.begin(); i != ports.end(); ++i) {
@@ -548,7 +513,7 @@ Delivery::target_gain ()
 	   we're not monitoring, then be quiet.
 	*/
 
-	if (_role == Main && _session.config.get_use_monitor_fades() && _no_outs_cuz_we_no_monitor) {
+	if (_no_outs_cuz_we_no_monitor) {
 		return GAIN_COEFF_ZERO;
 	}
 
diff --git a/libs/ardour/internal_send.cc b/libs/ardour/internal_send.cc
index fe57176ac7..e8e560c7c0 100644
--- a/libs/ardour/internal_send.cc
+++ b/libs/ardour/internal_send.cc
@@ -148,10 +148,10 @@ InternalSend::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame
 	} else {
 		if (role() == Listen) {
 			/* We're going to the monitor bus, so discard MIDI data */
-
+			
 			uint32_t const bufs_audio = bufs.count().get (DataType::AUDIO);
 			uint32_t const mixbufs_audio = mixbufs.count().get (DataType::AUDIO);
-
+			
 			/* monitor-section has same number of channels as master-bus (on creation).
 			 *
 			 * There is no clear answer what should happen when trying to PFL or AFL
@@ -190,21 +190,26 @@ InternalSend::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame
 
 	gain_t tgain = target_gain ();
 
-	_amp->set_gain (tgain, this);
+	if (tgain != _current_gain) {
+
+		/* target gain has changed */
+
+		_current_gain = Amp::apply_gain (mixbufs, _session.nominal_frame_rate(), nframes, _current_gain, tgain);
+
+	} else if (tgain == GAIN_COEFF_ZERO) {
 
-	if (tgain == GAIN_COEFF_ZERO && _amp->gain() == GAIN_COEFF_ZERO) {
 		/* we were quiet last time, and we're still supposed to be quiet.
-		 */
+		*/
 
 		_meter->reset ();
 		Amp::apply_simple_gain (mixbufs, nframes, GAIN_COEFF_ZERO);
 		goto out;
 
-	}
+	} else if (tgain != GAIN_COEFF_UNITY) {
 
-	/* These two calls will either set up gain automation or mark
-	   the amp as ready to use a simple scalar gain.
-	*/
+		/* target gain has not changed, but is not zero or unity */
+		Amp::apply_simple_gain (mixbufs, nframes, tgain);
+	}
 
 	_amp->set_gain_automation_buffer (_session.send_gain_automation_buffer ());
 	_amp->setup_gain_automation (start_frame, end_frame, nframes);
@@ -395,4 +400,4 @@ InternalSend::cycle_start (pframes_t /*nframes*/)
 	for (BufferSet::audio_iterator b = mixbufs.audio_begin(); b != mixbufs.audio_end(); ++b) {
 		b->prepare ();
 	}
-}
+}	
diff --git a/libs/ardour/send.cc b/libs/ardour/send.cc
index 2167c4319c..9d5fd619c3 100644
--- a/libs/ardour/send.cc
+++ b/libs/ardour/send.cc
@@ -86,6 +86,7 @@ Send::Send (Session& s, boost::shared_ptr<Pannable> p, boost::shared_ptr<MuteMas
 
 	//boost_debug_shared_ptr_mark_interesting (this, "send");
 
+	_amp.reset (new Amp (_session));
 	_meter.reset (new PeakMeter (_session, name()));
 
 	_delayline.reset (new DelayLine (_session, name()));
@@ -173,7 +174,7 @@ Send::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame, pframe
 	sendbufs.read_from (bufs, nframes);
 	assert(sendbufs.count() == bufs.count());
 
-	/* automatable gain control */
+	/* gain control */
 
 	_amp->set_gain_automation_buffer (_session.send_gain_automation_buffer ());
 	_amp->setup_gain_automation (start_frame, end_frame, nframes);