AU/AUv3: Ensured that prepareToPlay is called when an AU host enables/disables non-realtime mode

modules/juce_audio_plugin_client/AU/juce_AU_Wrapper.mm

@@ -610,10 +610,24 @@ public:
                 }
 
                 case kAudioUnitProperty_OfflineRender:
+                {
+                    auto shouldBeRealtime = (*reinterpret_cast<const UInt32*> (inData) != 0);
+
                     if (juceFilter != nullptr)
-                        juceFilter->setNonRealtime ((*(UInt32*) inData) != 0);
+                    {
+                        auto isCurrentlyRealtime = juceFilter->isNonRealtime();
+
+                        if (isCurrentlyRealtime != shouldBeRealtime)
+                        {
+                            const ScopedLock sl (juceFilter->getCallbackLock());
+
+                            juceFilter->setNonRealtime (shouldBeRealtime);
+                            juceFilter->prepareToPlay (getSampleRate(), (int) GetMaxFramesPerSlice());
+                        }
+                    }
 
                     return noErr;
+                }
 
                 default: break;
             }

modules/juce_audio_plugin_client/AU/juce_AUv3_Wrapper.mm

@@ -692,7 +692,19 @@ public:
     //==============================================================================
     AUInternalRenderBlock getInternalRenderBlock() override   { return internalRenderBlock;  }
     bool getRenderingOffline() override                       { return getAudioProcessor().isNonRealtime(); }
-    void setRenderingOffline (bool offline) override          { getAudioProcessor().setNonRealtime (offline); }
+    void setRenderingOffline (bool offline) override
+    {
+        auto& processor = getAudioProcessor();
+        auto isCurrentlyNonRealtime = processor.isNonRealtime();
+
+        if (isCurrentlyNonRealtime != offline)
+        {
+            ScopedLock callbackLock (processor.getCallbackLock());
+
+            processor.setNonRealtime (offline);
+            processor.prepareToPlay (processor.getSampleRate(), processor.getBlockSize());
+        }
+    }
 
     //==============================================================================
     NSString* getContextName() const    override              { return juceStringToNS (contextName); }