Added a fix to generate the AAX plug-in ID from the channel configuration (and not an arbitrary order in which JUCE probes configurations)

Also added the method AudioProcessor::getAAXPluginIDForMainBusConfig for developers to override the generation of AAX plug-in IDs so that their plug-ins remain backward compatible

modules/juce_audio_plugin_client/AAX/juce_AAX_Wrapper.cpp

@@ -1734,8 +1734,10 @@ namespace AAXClasses
         return meterIdx;
     }
 
-    static void createDescriptor (AAX_IComponentDescriptor& desc, int configIndex,
-                                  const AudioProcessor::BusesLayout& fullLayout, AudioProcessor& processor,
+    static void createDescriptor (AAX_IComponentDescriptor& desc,
+                                  const AudioProcessor::BusesLayout& fullLayout,
+                                  AudioProcessor& processor,
+                                  Array<int32>& pluginIds,
                                   const int numMeters)
     {
         AAX_EStemFormat aaxInputFormat  = getFormatForAudioChannelSet (fullLayout.getMainInputChannelSet(),  false);
@@ -1797,10 +1799,22 @@ namespace AAXClasses
 
         // This value needs to match the RTAS wrapper's Type ID, so that
         // the host knows that the RTAS/AAX plugins are equivalent.
-        properties->AddProperty (AAX_eProperty_PlugInID_Native,     'jcaa' + configIndex);
+        const int32 pluginID = processor.getAAXPluginIDForMainBusConfig (fullLayout.getMainInputChannelSet(),
+                                                                         fullLayout.getMainOutputChannelSet(),
+                                                                         false);
+
+        // The plugin id generated from your AudioProcessor's getAAXPluginIDForMainBusConfig callback
+        // it not unique. Please fix your implementation!
+        jassert (! pluginIds.contains (pluginID));
+        pluginIds.add (pluginID);
+
+        properties->AddProperty (AAX_eProperty_PlugInID_Native, pluginID);
 
        #if ! JucePlugin_AAXDisableAudioSuite
-        properties->AddProperty (AAX_eProperty_PlugInID_AudioSuite, 'jyaa' + configIndex);
+        properties->AddProperty (AAX_eProperty_PlugInID_AudioSuite,
+                                 processor.getAAXPluginIDForMainBusConfig (fullLayout.getMainInputChannelSet(),
+                                                                           fullLayout.getMainOutputChannelSet(),
+                                                                           true));
        #endif
 
        #if JucePlugin_AAXDisableMultiMono
@@ -1879,7 +1893,7 @@ namespace AAXClasses
         }
 
        #else
-        int configIndex = 0;
+        Array<int32> pluginIds;
 
         const int numIns  = numInputBuses  > 0 ? AAX_eStemFormatNum : 0;
         const int numOuts = numOutputBuses > 0 ? AAX_eStemFormatNum : 0;
@@ -1900,14 +1914,14 @@ namespace AAXClasses
 
                 if (AAX_IComponentDescriptor* const desc = descriptor.NewComponentDescriptor())
                 {
-                    createDescriptor (*desc, configIndex++, fullLayout, *plugin, numMeters);
+                    createDescriptor (*desc, fullLayout, *plugin, pluginIds, numMeters);
                     check (descriptor.AddComponent (desc));
                 }
             }
         }
 
         // You don't have any supported layouts
-        jassert (configIndex > 0);
+        jassert (pluginIds.size() > 0);
        #endif
     }
 }

modules/juce_audio_processors/processors/juce_AudioProcessor.cpp

@@ -1302,6 +1302,45 @@ AudioProcessor::BusesProperties AudioProcessor::BusesProperties::withOutput (con
     return retval;
 }
 
+//==============================================================================
+int32 AudioProcessor::getAAXPluginIDForMainBusConfig (const AudioChannelSet& mainInputLayout,
+                                                      const AudioChannelSet& mainOutputLayout,
+                                                      const bool idForAudioSuite) const
+{
+    int uniqueFormatId = 0;
+    for (int dir = 0; dir < 2; ++dir)
+    {
+        const bool isInput = (dir == 0);
+        const AudioChannelSet& set = (isInput ? mainInputLayout : mainOutputLayout);
+        int aaxFormatIndex = 0;
+
+        if      (set == AudioChannelSet::disabled())           aaxFormatIndex = 0;
+        else if (set == AudioChannelSet::mono())               aaxFormatIndex = 1;
+        else if (set == AudioChannelSet::stereo())             aaxFormatIndex = 2;
+        else if (set == AudioChannelSet::createLCR())          aaxFormatIndex = 3;
+        else if (set == AudioChannelSet::createLCRS())         aaxFormatIndex = 4;
+        else if (set == AudioChannelSet::quadraphonic())       aaxFormatIndex = 5;
+        else if (set == AudioChannelSet::create5point0())      aaxFormatIndex = 6;
+        else if (set == AudioChannelSet::create5point1())      aaxFormatIndex = 7;
+        else if (set == AudioChannelSet::create6point0())      aaxFormatIndex = 8;
+        else if (set == AudioChannelSet::create6point1())      aaxFormatIndex = 9;
+        else if (set == AudioChannelSet::create7point0())      aaxFormatIndex = 10;
+        else if (set == AudioChannelSet::create7point1())      aaxFormatIndex = 11;
+        else if (set == AudioChannelSet::create7point0SDDS())  aaxFormatIndex = 12;
+        else if (set == AudioChannelSet::create7point1SDDS())  aaxFormatIndex = 13;
+        else
+        {
+            // AAX does not support this format and the wrapper should not have
+            // called this method with this layout
+            jassertfalse;
+        }
+
+        uniqueFormatId = (uniqueFormatId * 16) + aaxFormatIndex;
+    }
+
+    return (idForAudioSuite ? 0x6a796161 /* 'jyaa' */ : 0x6a636161 /* 'jcaa' */) + uniqueFormatId;
+}
+
 
 //==============================================================================
 void AudioProcessorListener::audioProcessorParameterChangeGestureBegin (AudioProcessor*, int) {}

modules/juce_audio_processors/processors/juce_AudioProcessor.h

@@ -1263,6 +1263,20 @@ public:
     */
     void setRateAndBufferSizeDetails (double sampleRate, int blockSize) noexcept;
 
+    //==============================================================================
+    /** AAX plug-ins need to report a unique "plug-in id" for every audio layout
+        configuration that your AudioProcessor supports on the main bus. Override this
+        function if you want your AudioProcessor to use a custom "plug-in id" (for example
+        to stay backward compatible with older versions of JUCE).
+
+        The default implementation will compute a unique integer from the input and output
+        layout and add this value to the 4 character code 'jcaa' (for native AAX) or 'jyaa'
+        (for AudioSuite plug-ins).
+    */
+    virtual int32 getAAXPluginIDForMainBusConfig (const AudioChannelSet& mainInputLayout,
+                                                  const AudioChannelSet& mainOutputLayout,
+                                                  bool idForAudioSuite) const;
+
     //==============================================================================
     /** Not for public use - this is called before deleting an editor component. */
     void editorBeingDeleted (AudioProcessorEditor*) noexcept;