From 3722b8a94f3818f5b8a7e8ce2d7de806def835fb Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Tue, 2 Mar 2021 03:21:08 +0100
Subject: [PATCH] VST3: work around plugins with missing controller state

If a plugin implements Vst::IComponent::set_state() but
does not implement Vst::IEditController::setComponentState()
nor dedicated get/setState interface for the IEditController,
querying the parameters using Vst::IEditController::getParamNormalized()
returns values that do reflect the restored state.

In this case the host needs to save/restore all control-parameters,
and ignore values reported by ::getParamNormalized().

This fixes a state save/restore issue with softube.vst3, however
vstpresets are still broken: the GUI (IComponent) is updated,
however the controller isn't.
---
 libs/ardour/vst3_plugin.cc | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/libs/ardour/vst3_plugin.cc b/libs/ardour/vst3_plugin.cc
index 8813d56f1f..05f3961b33 100644
--- a/libs/ardour/vst3_plugin.cc
+++ b/libs/ardour/vst3_plugin.cc
@@ -1754,10 +1754,10 @@ VST3PI::synchronize_states ()
 			std::cerr << "Failed to synchronize VST3 component <> controller state\n";
 			stream.hexdump (0);
 #endif
-			return false;
 		}
+		return res == kResultOk;
 	}
-	return true;
+	return false;
 }
 
 void
@@ -2259,6 +2259,7 @@ VST3PI::load_state (RAMStream& stream)
 	}
 
 	bool rv = true;
+	bool synced = false;
 
 	/* parse chunks */
 	for (ChunkEntryVector::const_iterator i = entries.begin (); i != entries.end (); ++i) {
@@ -2274,6 +2275,10 @@ VST3PI::load_state (RAMStream& stream)
 			s.rewind ();
 			tresult re2 = _controller->setComponentState (&s);
 
+			if (re2 == kResultOk) {
+				synced = true;
+			}
+
 			if (!(re2 == kResultOk || re2 == kNotImplemented || res == kResultOk || res == kNotImplemented)) {
 				DEBUG_TRACE (DEBUG::VST3Config, "VST3PI::load_state: failed to restore component state\n");
 				rv = false;
@@ -2281,6 +2286,10 @@ VST3PI::load_state (RAMStream& stream)
 		} else if (is_equal_ID (i->_id, Vst::getChunkID (Vst::kControllerState))) {
 			stream.seek (i->_offset, IBStream::kIBSeekSet, &seek_result);
 			tresult res = _controller->setState (&stream);
+			if (res == kResultOk) {
+				synced = true;
+			}
+
 			if (!(res == kResultOk || res == kNotImplemented)) {
 				DEBUG_TRACE (DEBUG::VST3Config, "VST3PI::load_state: failed to restore controller state\n");
 				rv = false;
@@ -2302,8 +2311,11 @@ VST3PI::load_state (RAMStream& stream)
 			DEBUG_TRACE (DEBUG::VST3Config, "VST3PI::load_state: ignored unsupported state chunk.\n");
 		}
 	}
+	if (rv && !synced) {
+		synced = synchronize_states ();
+	}
 
-	if (rv) {
+	if (rv && synced) {
 		update_shadow_data ();
 	}
 	return rv;