Delegated plugin configuration is now always successful.. except

..in case of outright errors (e.g. data format mismatch)
or non-implemented edge-cases e.g. midi generators
(no audio in, no midi in, no audio-out) or control-data filters (only
control ports).

libs/ardour/ardour/audio_unit.h

@@ -103,7 +103,7 @@ class LIBARDOUR_API AUPlugin : public ARDOUR::Plugin
 
 	bool has_editor () const;
 
-	bool can_support_io_configuration (const ChanCount& in, ChanCount& out);
+	bool can_support_io_configuration (const ChanCount& in, ChanCount& out, ChanCount* imprecise);
 	ChanCount output_streams() const;
 	ChanCount input_streams() const;
 	bool configure_io (ChanCount in, ChanCount out);

libs/ardour/ardour/luaproc.h

@@ -93,7 +93,7 @@ public:
 	bool load_preset (PresetRecord) { return false; }
 	bool has_editor() const { return false; }
 
-	bool can_support_io_configuration (const ChanCount& in, ChanCount& out);
+	bool can_support_io_configuration (const ChanCount& in, ChanCount& out, ChanCount* imprecise);
 	bool configure_io (ChanCount in, ChanCount out);
 
 	ChanCount output_streams() const { return _configured_out; }

libs/ardour/ardour/plugin.h

@@ -210,7 +210,7 @@ class LIBARDOUR_API Plugin : public PBD::StatefulDestructible, public Latent
 	/* specific types of plugins can overload this. As of September 2008, only
 	   AUPlugin does this.
 	*/
-	virtual bool can_support_io_configuration (const ChanCount& /*in*/, ChanCount& /*out*/) { return false; }
+	virtual bool can_support_io_configuration (const ChanCount& /*in*/, ChanCount& /*out*/, ChanCount* imprecise = 0) { return false; }
 	virtual ChanCount output_streams() const;
 	virtual ChanCount input_streams() const;
 

libs/ardour/audio_unit.cc

@@ -1129,21 +1129,18 @@ AUPlugin::output_streams() const
 }
 
 bool
-AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out)
+AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out, ChanCount* imprecise)
 {
 	// Note: We never attempt to multiply-instantiate plugins to meet io configurations.
 
-	int32_t audio_in = in.n_audio();
+	const int32_t audio_in = in.n_audio();
 	int32_t audio_out;
-	bool found = false;
 	AUPluginInfoPtr pinfo = boost::dynamic_pointer_cast<AUPluginInfo>(get_info());
 
 	/* lets check MIDI first */
 
-	if (in.n_midi() > 0) {
+	if (in.n_midi() > 0 && !_has_midi_input && !imprecise) {
-		if (!_has_midi_input) {
+		return false;
-			return false;
-		}
 	}
 
 	vector<pair<int,int> >& io_configs = pinfo->cache.io_configs;
@@ -1201,13 +1198,13 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 			out.set (DataType::MIDI, 0);
 			out.set (DataType::AUDIO, audio_out);
 
-			return 1;
+			return true;
 		}
 	}
 
 	/* now allow potentially "imprecise" matches */
-
 	audio_out = -1;
+	bool found = false;
 
 	for (vector<pair<int,int> >::iterator i = io_configs.begin(); i != io_configs.end(); ++i) {
 
@@ -1223,26 +1220,17 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 		}
 
 		if (possible_in == 0) {
-
+			/* no inputs, generators & instruments */
-			/* instrument plugin, always legal but throws away inputs ...
-			*/
-
 			if (possible_out == -1) {
 				/* any configuration possible, provide stereo output */
 				audio_out = 2;
 				found = true;
 			} else if (possible_out == -2) {
-				/* plugins shouldn't really use (0,-2) but might.
+				/* invalid, should be (0, -1) */
-				   any configuration possible, provide stereo output
-				*/
 				audio_out = 2;
 				found = true;
 			} else if (possible_out < -2) {
-				/* explicitly variable number of outputs.
+				/* explicitly variable number of outputs. */
-				 *
-				 * We really need to ask the user in this case.
-				 * stereo will be correct in 99.9% of all cases.
-				 */
 				audio_out = 2;
 				found = true;
 			} else {
@@ -1253,11 +1241,9 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 		}
 
 		if (possible_in == -1) {
-
 			/* wildcard for input */
-
 			if (possible_out == -1) {
-				/* out much match in */
+				/* out must match in */
 				audio_out = audio_in;
 				found = true;
 			} else if (possible_out == -2) {
@@ -1276,15 +1262,12 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 		}
 
 		if (possible_in == -2) {
-
 			if (possible_out == -1) {
 				/* any configuration possible, pick matching */
 				audio_out = audio_in;
 				found = true;
 			} else if (possible_out == -2) {
-				/* plugins shouldn't really use (-2,-2) but might.
+				/* invalid. interpret as (-1, -1) */
-				   interpret as (-1,-1).
-				*/
 				audio_out = audio_in;
 				found = true;
 			} else if (possible_out < -2) {
@@ -1299,30 +1282,24 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 		}
 
 		if (possible_in < -2) {
-
 			/* explicit variable number of inputs */
-
+			if (audio_in > -possible_in && imprecise != NULL) {
-			if (audio_in > -possible_in) {
+				// hide inputs ports
-				/* request is too large */
+				imprecise->set (DataType::AUDIO, -possible_in);
 			}
 
-
+			if (audio_in > -possible_in && imprecise == NULL) {
-			if (possible_out == -1) {
+				/* request is too large */
+			} else if (possible_out == -1) {
 				/* any output configuration possible, provide stereo out */
 				audio_out = 2;
 				found = true;
 			} else if (possible_out == -2) {
-				/* plugins shouldn't really use (<-2,-2) but might.
+				/* invalid. interpret as (<-2, -1) */
-				   interpret as (<-2,-1): any configuration possible, provide stereo output
-				*/
 				audio_out = 2;
 				found = true;
 			} else if (possible_out < -2) {
-				/* explicitly variable number of outputs.
+				/* explicitly variable number of outputs, pick stereo */
-				 *
-				 * We really need to ask the user in this case.
-				 * stereo will be correct in 99.9% of all cases.
-				 */
 				audio_out = 2;
 				found = true;
 			} else {
@@ -1333,9 +1310,7 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& 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;
@@ -1368,6 +1343,38 @@ AUPlugin::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 		}
 
 	}
+	if (!found && imprecise) {
+		/* try harder */
+		for (vector<pair<int,int> >::iterator i = io_configs.begin(); i != io_configs.end(); ++i) {
+			int possible_in = io["audio_in"];
+			int possible_out = io["audio_out"];
+
+			assert (possible_in > 0); // all other cases will have been matched above
+			assert (possible_out !=0 || possible_in !=0); // already handled above
+
+			imprecise->set (DataType::AUDIO, possible_in);
+			if (possible_out == -1 || possible_out == -2) {
+				audio_out = 2;
+				found = true;
+			} else if (possible_out < -2) {
+				/* explicitly variable number of outputs, pick maximum */
+				audio_out = -possible_out;
+				found = true;
+			} 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;
+			}
+		}
+	}
 
 	if (found) {
 		out.set (DataType::MIDI, 0); /// XXX

libs/ardour/luaproc.cc

@@ -305,9 +305,11 @@ LuaProc::load_script ()
 }
 
 bool
-LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out)
+LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out, ChanCount* imprecise)
 {
-	if (in.n_midi() > 0 && !_has_midi_input) {
+	// caller must hold process lock (no concurrent calls to interpreter
+
+	if (in.n_midi() > 0 && !_has_midi_input && !imprecise) {
 		return false;
 	}
 
@@ -344,8 +346,9 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 		return false;
 	}
 
-	int32_t audio_in = in.n_audio ();
+	const int32_t audio_in = in.n_audio ();
 	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.
@@ -353,6 +356,7 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 		audio_out = audio_in;
 	}
 
+
 	for (luabridge::Iterator i (iotable); !i.isNil (); ++i) {
 		assert (i.value ().type () == LUA_TTABLE);
 		luabridge::LuaRef io (i.value ());
@@ -406,7 +410,7 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 		if (possible_in == -1) {
 			/* wildcard for input */
 			if (possible_out == -1) {
-				/* out much match in */
+				/* out must match in */
 				audio_out = audio_in;
 				found = true;
 			} else if (possible_out == -2) {
@@ -447,10 +451,14 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 
 		if (possible_in < -2) {
 			/* explicit variable number of inputs */
-			if (audio_in > -possible_in) {
+			if (audio_in > -possible_in && imprecise != NULL) {
-				/* request is too large */
+				// hide inputs ports
+				imprecise->set (DataType::AUDIO, -possible_in);
 			}
-			if (possible_out == -1) {
+
+			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;
@@ -495,11 +503,48 @@ LuaProc::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 		}
 	}
 
+	if (!found && imprecise) {
+		/* try harder */
+		for (luabridge::Iterator i (iotable); !i.isNil (); ++i) {
+			assert (i.value ().type () == LUA_TTABLE);
+			luabridge::LuaRef io (i.value ());
+
+			int possible_in = io["audio_in"];
+			int possible_out = io["audio_out"];
+
+			assert (possible_in > 0); // all other cases will have been matched above
+			assert (possible_out !=0 || possible_in !=0); // already handled above
+
+			imprecise->set (DataType::AUDIO, possible_in);
+			if (possible_out == -1 || possible_out == -2) {
+				audio_out = 2;
+				found = true;
+			} else if (possible_out < -2) {
+				/* explicitly variable number of outputs, pick maximum */
+				audio_out = -possible_out;
+				found = true;
+			} 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;
+			}
+		}
+	}
+
+
 	if (!found) {
 		return false;
 	}
 
-	out.set (DataType::MIDI, 0);
+	out.set (DataType::MIDI, midi_out); // currently always zero
 	out.set (DataType::AUDIO, audio_out);
 	return true;
 }

libs/ardour/plugin_insert.cc

@@ -915,18 +915,22 @@ PluginInsert::configure_io (ChanCount in, ChanCount out)
 		}
 		break;
 	case Delegate:
-		if (_match.strict_io) {
+		{
 			ChanCount dout;
-			bool const r = _plugins.front()->can_support_io_configuration (in, dout);
+			ChanCount useins;
+			bool const r = _plugins.front()->can_support_io_configuration (in, dout, &useins);
 			assert (r);
-			if (_plugins.front()->configure_io (in, dout) == false) {
+			assert (_match.strict_io || dout.n_audio() == out.n_audio()); // sans midi bypass
+			if (useins.n_audio() == 0) {
+				useins = in;
+			}
+			if (_plugins.front()->configure_io (useins, dout) == false) {
 				PluginIoReConfigure (); /* EMIT SIGNAL */
 				_configured = false;
 				return false;
 			}
-			break;
 		}
-		// no break --  fall through
+		break;
 	default:
 		if (_plugins.front()->configure_io (in, out) == false) {
 			PluginIoReConfigure (); /* EMIT SIGNAL */
@@ -1003,7 +1007,7 @@ PluginInsert::configure_io (ChanCount in, ChanCount out)
 
 	if (mapping_changed) {
 		PluginMapChanged (); /* EMIT SIGNAL */
-#if 1
+#ifndef NDEBUG
 		uint32_t pc = 0;
 		cout << "----<<----\n";
 		for (Plugins::iterator i = _plugins.begin(); i != _plugins.end(); ++i, ++pc) {
@@ -1126,10 +1130,13 @@ PluginInsert::private_can_support_io_configuration (ChanCount const & inx, ChanC
 	}
 
 	if (info->reconfigurable_io()) {
-		// houston, we have a problem.
+		ChanCount useins;
-		// TODO: match closest closes available config.
+		bool const r = _plugins.front()->can_support_io_configuration (inx, out, &useins);
-		// also handle  strict_io
+		if (!r) {
-		return Match (Impossible, 0);
+			// houston, we have a problem.
+			return Match (Impossible, 0);
+		}
+		return Match (Delegate, 1);
 	}
 
 	// add at least as many plugins so that output count matches input count
@@ -1175,7 +1182,6 @@ PluginInsert::automatic_can_support_io_configuration (ChanCount const & inx, Cha
 		if (!r) {
 			return Match (Impossible, 0);
 		}
-
 		return Match (Delegate, 1);
 	}