find a good match for variable i/o plugins

3 files changed, 137 insertions, 159 deletions

diff --git a/libs/ardour/audio_unit.cc b/libs/ardour/audio_unit.cc
index 73a08fe7ac..cab6a56c92 100644
--- a/libs/ardour/audio_unit.cc
+++ b/libs/ardour/audio_unit.cc
@@ -1150,16 +1150,8 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out, Cha
 	DEBUG_TRACE (DEBUG::AudioUnits, string_compose ("%1 has %2 IO configurations, looking for %3 in, %4 out\n",
 							name(), io_configs.size(), in, out));
 
-	//Ardour expects the plugin to tell it the output
-	//configuration but AU plugins can have multiple I/O
-	//configurations in most cases. so first lets see
-	//if there's a configuration that keeps out==in
-
-	if (in.n_midi() > 0 && audio_in == 0) {
-		audio_out = 2; // prefer stereo version if available.
-	} else {
-		audio_out = audio_in;
-	}
+	// preferred setting (provided by plugin_insert)
+	audio_out = out.n_audio ();
 
 	/* kAudioUnitProperty_SupportedNumChannels
 	 * https://developer.apple.com/library/mac/documentation/MusicAudio/Conceptual/AudioUnitProgrammingGuide/TheAudioUnit/TheAudioUnit.html#//apple_ref/doc/uid/TP40003278-CH12-SW20
@@ -1208,6 +1200,21 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out, Cha
 	audio_out = -1;
 	bool found = false;
 
+	float penalty = 9999;
+	const int preferred_out = out.n_audio ();
+	int used_possible_in = 0;
+
+#define FOUNDCFG(nch) {                                  \
+	float p = fabsf ((float)(nch) - preferred_out);  \
+	if ((nch) > preferred_out) { p *= 1.1; }         \
+	if (p < penalty) {                               \
+		used_possible_in = possible_in;          \
+		audio_out = (nch);                       \
+		penalty = p;                             \
+		found = true;                            \
+	}                                                \
+}
+
 	for (vector<pair<int,int> >::iterator i = io_configs.begin(); i != io_configs.end(); ++i) {
 
 		int32_t possible_in = i->first;
@@ -1225,20 +1232,16 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out, Cha
 			/* no inputs, generators & instruments */
 			if (possible_out == -1) {
 				/* any configuration possible, provide stereo output */
-				audio_out = 2;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out == -2) {
 				/* invalid, should be (0, -1) */
-				audio_out = 2;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
-				/* explicitly variable number of outputs. */
-				audio_out = 2;
-				found = true;
+				/* variable number of outputs up to -N, */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
+				FOUNDCFG (possible_out);
 			}
 		}
 
@@ -1246,40 +1249,35 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out, Cha
 			/* wildcard for input */
 			if (possible_out == -1) {
 				/* out must match in */
-				audio_out = audio_in;
-				found = true;
+				FOUNDCFG (audio_in);
 			} else if (possible_out == -2) {
 				/* any configuration possible, pick matching */
-				audio_out = audio_in;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
 				/* explicitly variable number of outputs, pick maximum */
-				audio_out = -possible_out;
-				found = true;
+				FOUNDCFG (max (-possible_out, preferred_out));
+				/* and try min, too, in case the penalty is lower */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
+				FOUNDCFG (possible_out);
 			}
 		}
 
 		if (possible_in == -2) {
 			if (possible_out == -1) {
 				/* any configuration possible, pick matching */
-				audio_out = audio_in;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out == -2) {
 				/* invalid. interpret as (-1, -1) */
-				audio_out = audio_in;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
-				/* explicitly variable number of outputs, pick maximum */
-				audio_out = -possible_out;
-				found = true;
+				/* invalid,  interpret as (<-2, <-2)
+				 * variable number of outputs up to -N, */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
+				FOUNDCFG (possible_out);
 			}
 		}
 
@@ -1294,57 +1292,40 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out, Cha
 				/* request is too large */
 			} else if (possible_out == -1) {
 				/* any output configuration possible, provide stereo out */
-				audio_out = 2;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out == -2) {
 				/* invalid. interpret as (<-2, -1) */
-				audio_out = 2;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
-				/* explicitly variable number of outputs, pick stereo */
-				audio_out = 2;
-				found = true;
+				/* variable number of outputs up to -N, */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
+				FOUNDCFG (possible_out);
 			}
 		}
 
 		if (possible_in && (possible_in == audio_in)) {
 			/* exact number of inputs ... must match obviously */
 			if (possible_out == -1) {
-				/* any output configuration possible, provide stereo output */
-				audio_out = 2;
-				found = true;
+				/* any output configuration possible */
+				FOUNDCFG (preferred_out);
 			} else if (possible_out == -2) {
 				/* plugins shouldn't really use (>0,-2) but might.
-				   interpret as (>0,-1):
-				   any output configuration possible, provide stereo output
-				*/
-				audio_out = 2;
-				found = true;
+				 * interpret as (>0,-1):
+				 */
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
-				/* explicitly variable number of outputs, pick maximum */
-				audio_out = -possible_out;
-				found = true;
+				/* > 0, < -2 is not specified
+				 * interpret as up to -N */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
-			}
-		}
-
-		if (found) {
-			if (possible_in < -2 && audio_in == 0) {
-				// input-port count cannot be zero, use as many ports
-				// as outputs, but at most abs(possible_in)
-				audio_input_cnt = max (1, min (audio_out, -possible_in));
+				FOUNDCFG (possible_out);
 			}
-			break;
 		}
-
 	}
+
 	if (!found && imprecise) {
 		/* try harder */
 		for (vector<pair<int,int> >::iterator i = io_configs.begin(); i != io_configs.end(); ++i) {
@@ -1356,29 +1337,26 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out, Cha
 
 			imprecise->set (DataType::AUDIO, possible_in);
 			if (possible_out == -1 || possible_out == -2) {
-				audio_out = 2;
-				found = true;
+				FOUNDCFG (2);
 			} else if (possible_out < -2) {
 				/* explicitly variable number of outputs, pick maximum */
-				audio_out = -possible_out;
-				found = true;
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
-			}
-
-			if (found) {
-				// ideally we'll keep iterating and take the "best match"
-				// whatever "best" means:
-				// least unconnected inputs, least silenced inputs,
-				// closest match of inputs == outputs
-				break;
+				FOUNDCFG (possible_out);
 			}
+			// ideally we'll also find the closest, best matching
+			// input configuration with minimal output penalty...
 		}
 	}
 
 	if (found) {
+		if (used_possible_in < -2 && audio_in == 0) {
+			// input-port count cannot be zero, use as many ports
+			// as outputs, but at most abs(possible_in)
+			audio_input_cnt = max (1, min (audio_out, -used_possible_in));
+		}
+
 		out.set (DataType::MIDI, 0); /// XXX
 		out.set (DataType::AUDIO, audio_out);
 		DEBUG_TRACE (DEBUG::AudioUnits, string_compose ("\tCHOSEN: in %1 out %2\n", in, out));
diff --git a/libs/ardour/luaproc.cc b/libs/ardour/luaproc.cc
index 7af6f587a4..fc9e5de537 100644
--- a/libs/ardour/luaproc.cc
+++ b/libs/ardour/luaproc.cc
@@ -354,12 +354,9 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out, Chan
 	int32_t audio_out;
 	int32_t midi_out = 0; // TODO handle  _has_midi_output
 
-	if (in.n_midi() > 0 && audio_in == 0) {
-		audio_out = 2; // prefer stereo version if available.
-	} else {
-		audio_out = audio_in;
-	}
-
+	// preferred setting (provided by plugin_insert)
+	assert (out.n_audio () > 0);
+	audio_out = out.n_audio ();
 
 	for (luabridge::Iterator i (iotable); !i.isNil (); ++i) {
 		assert (i.value ().type () == LUA_TTABLE);
@@ -380,6 +377,19 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out, Chan
 	audio_out = -1;
 	bool found = false;
 
+	float penalty = 9999;
+	const int preferred_out = out.n_audio ();
+
+#define FOUNDCFG(nch) {                                  \
+	float p = fabsf ((float)(nch) - preferred_out);  \
+	if ((nch) > preferred_out) { p *= 1.1; }         \
+	if (p < penalty) {                               \
+		audio_out = (nch);                       \
+		penalty = p;                             \
+		found = true;                            \
+	}                                                \
+}
+
 	for (luabridge::Iterator i (iotable); !i.isNil (); ++i) {
 		assert (i.value ().type () == LUA_TTABLE);
 		luabridge::LuaRef io (i.value ());
@@ -393,21 +403,17 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out, Chan
 		if (possible_in == 0) {
 			/* no inputs, generators & instruments */
 			if (possible_out == -1) {
-				/* any configuration possible, provide stereo output */
-				audio_out = 2;
-				found = true;
+				/* any configuration possible, stereo output */
+				FOUNDCFG (preferred_out);
 			} else if (possible_out == -2) {
 				/* invalid, should be (0, -1) */
-				audio_out = 2;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
-				/* variable number of outputs. -> whatever */
-				audio_out = 2;
-				found = true;
+				/* variable number of outputs up to -N, */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
+				FOUNDCFG (possible_out);
 			}
 		}
 
@@ -415,20 +421,18 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out, Chan
 			/* wildcard for input */
 			if (possible_out == -1) {
 				/* out must match in */
-				audio_out = audio_in;
-				found = true;
+				FOUNDCFG (audio_in);
 			} else if (possible_out == -2) {
 				/* any configuration possible, pick matching */
-				audio_out = audio_in;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
 				/* explicitly variable number of outputs, pick maximum */
-				audio_out = -possible_out;
-				found = true;
+				FOUNDCFG (max (-possible_out, preferred_out));
+				/* and try min, too, in case the penalty is lower */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
+				FOUNDCFG (possible_out);
 			}
 		}
 
@@ -436,20 +440,17 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out, Chan
 
 			if (possible_out == -1) {
 				/* any configuration possible, pick matching */
-				audio_out = audio_in;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out == -2) {
 				/* invalid. interpret as (-1, -1) */
-				audio_out = audio_in;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
-				/* explicitly variable number of outputs, pick maximum */
-				audio_out = -possible_out;
-				found = true;
+				/* invalid,  interpret as (<-2, <-2)
+				 * variable number of outputs up to -N, */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
+				FOUNDCFG (possible_out);
 			}
 		}
 
@@ -463,48 +464,37 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out, Chan
 			if (audio_in > -possible_in && imprecise == NULL) {
 				/* request is too large */
 			} else if (possible_out == -1) {
-				/* any output configuration possible, provide stereo out */
-				audio_out = 2;
-				found = true;
+				/* any output configuration possible */
+				FOUNDCFG (preferred_out);
 			} else if (possible_out == -2) {
 				/* invalid. interpret as (<-2, -1) */
-				audio_out = 2;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
-				/* explicitly variable number of outputs, pick stereo */
-				audio_out = 2;
-				found = true;
+				/* variable number of outputs up to -N, */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
+				FOUNDCFG (possible_out);
 			}
 		}
 
 		if (possible_in && (possible_in == audio_in)) {
 			/* exact number of inputs ... must match obviously */
 			if (possible_out == -1) {
-				/* any output configuration possible, provide stereo output */
-				audio_out = 2;
-				found = true;
+				/* any output configuration possible */
+				FOUNDCFG (preferred_out);
 			} else if (possible_out == -2) {
 				/* invalid. interpret as (>0, -1) */
-				audio_out = 2;
-				found = true;
+				FOUNDCFG (preferred_out);
 			} else if (possible_out < -2) {
-				/* explicitly variable number of outputs, pick maximum */
-				audio_out = -possible_out;
-				found = true;
+				/* > 0, < -2 is not specified
+				 * interpret as up to -N */
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
+				FOUNDCFG (possible_out);
 			}
 		}
-
-		if (found) {
-			break;
-		}
 	}
 
 	if (!found && imprecise) {
@@ -521,25 +511,16 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out, Chan
 
 			imprecise->set (DataType::AUDIO, possible_in);
 			if (possible_out == -1 || possible_out == -2) {
-				audio_out = 2;
-				found = true;
+				FOUNDCFG (2);
 			} else if (possible_out < -2) {
 				/* explicitly variable number of outputs, pick maximum */
-				audio_out = -possible_out;
-				found = true;
+				FOUNDCFG (min (-possible_out, preferred_out));
 			} else {
 				/* exact number of outputs */
-				audio_out = possible_out;
-				found = true;
-			}
-
-			if (found) {
-				// ideally we'll keep iterating and take the "best match"
-				// whatever "best" means:
-				// least unconnected inputs, least silenced inputs,
-				// closest match of inputs == outputs
-				break;
+				FOUNDCFG (possible_out);
 			}
+			// ideally we'll also find the closest, best matching
+			// input configuration with minimal output penalty...
 		}
 	}
 
diff --git a/libs/ardour/plugin_insert.cc b/libs/ardour/plugin_insert.cc
index 74c169196d..2005d5b2e2 100644
--- a/libs/ardour/plugin_insert.cc
+++ b/libs/ardour/plugin_insert.cc
@@ -258,7 +258,6 @@ PluginInsert::internal_input_streams() const
 	PluginInfoPtr info = _plugins.front()->get_info();
 
 	if (info->reconfigurable_io()) {
-		assert (_plugins.size() == 1);
 		in = _plugins.front()->input_streams();
 	} else {
 		in = info->n_inputs;
@@ -1381,14 +1380,22 @@ PluginInsert::configure_io (ChanCount in, ChanCount out)
 		break;
 	case Delegate:
 		{
-			ChanCount dout;
+			ChanCount dout (in); // hint
+			if (_custom_cfg) { 
+				dout = _custom_out;
+			} else if (dout.n_midi () > 0 && dout.n_audio () == 0) {
+				dout.set (DataType::AUDIO, 2);
+			}
+			if (out.n_audio () == 0) { out.set (DataType::AUDIO, 1); }
 			ChanCount useins;
 			bool const r = _plugins.front()->can_support_io_configuration (in, dout, &useins);
 			assert (r);
-			assert (_match.strict_io || dout.n_audio() == out.n_audio()); // sans midi bypass
+			assert (dout.n_audio() <= out.n_audio()); // sans midi bypass
 			if (useins.n_audio() == 0) {
 				useins = in;
 			}
+			DEBUG_TRACE (DEBUG::ChanMapping, string_compose ("Delegate configuration: %1 %2 %3\n", name(), useins, dout));
+
 			if (_plugins.front()->configure_io (useins, dout) == false) {
 				PluginIoReConfigure (); /* EMIT SIGNAL */
 				_configured = false;
@@ -1542,8 +1549,13 @@ PluginInsert::private_can_support_io_configuration (ChanCount const & inx, ChanC
 
 	/* if a user specified a custom cfg, so be it. */
 	if (_custom_cfg) {
+		PluginInfoPtr info = _plugins.front()->get_info();
 		out = _custom_out;
-		return Match (ExactMatch, get_count(), _strict_io, true); // XXX
+		if (info->reconfigurable_io()) {
+			return Match (Delegate, get_count(), _strict_io, true);
+		} else {
+			return Match (ExactMatch, get_count(), _strict_io, true);
+		}
 	}
 
 	/* try automatic configuration */
@@ -1601,7 +1613,9 @@ PluginInsert::private_can_support_io_configuration (ChanCount const & inx, ChanC
 
 	if (info->reconfigurable_io()) {
 		ChanCount useins;
-		// TODO add sidechains here
+		out = inx; // hint
+		if (out.n_midi () > 0 && out.n_audio () == 0) { out.set (DataType::AUDIO, 2); }
+		if (out.n_audio () == 0) { out.set (DataType::AUDIO, 1); }
 		bool const r = _plugins.front()->can_support_io_configuration (inx, out, &useins);
 		if (!r) {
 			// houston, we have a problem.
@@ -1665,7 +1679,12 @@ PluginInsert::automatic_can_support_io_configuration (ChanCount const & inx, Cha
 	ChanCount midi_bypass;
 
 	if (info->reconfigurable_io()) {
-		/* Plugin has flexible I/O, so delegate to it */
+		/* Plugin has flexible I/O, so delegate to it
+		 * pre-seed outputs, plugin tries closest match
+		 */
+		out = in; // hint
+		if (out.n_midi () > 0 && out.n_audio () == 0) { out.set (DataType::AUDIO, 2); }
+		if (out.n_audio () == 0) { out.set (DataType::AUDIO, 1); }
 		bool const r = _plugins.front()->can_support_io_configuration (in, out);
 		if (!r) {
 			return Match (Impossible, 0);