Plug-In wrappers and hosting code now support infinite tail times

BREAKING-CHANGES.txt

@@ -4,6 +4,25 @@ JUCE breaking changes
 Develop
 =======
 
+Change
+------
+AudioProcessor::getTailLengthSeconds can now return infinity for VST/VST3/AU/AUv3
+
+Possible Issues
+---------------
+If you are using the result of getTailLengthSeconds to allocate a buffer in your host,
+then your host will now likely crash when loading a plug-in with an infinite tail time.
+
+Workaround
+----------
+Re-write your code to not use the result of getTailLengthSeconds directly to allocate
+a buffer.
+
+Rationale
+---------
+
+Before this change there was no way for a JUCE plug-in to report an infinite tail time. 
+
 
 Version 5.3.2
 =============

modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp

@@ -317,12 +317,15 @@ public:
         if (processor->supportsDoublePrecisionProcessing())
             vstEffect.flags |= vstEffectFlagInplaceDoubleAudio;
 
+        vstEffect.flags |= vstEffectFlagDataInChunks;
+
        #if JucePlugin_IsSynth
         vstEffect.flags |= vstEffectFlagIsSynth;
+       #else
+        if (processor->getTailLengthSeconds() == 0.0)
+            vstEffect.flags |= vstEffectFlagSilenceInProducesSilenceOut;
        #endif
 
-        vstEffect.flags |= vstEffectFlagDataInChunks;
-
         activePlugins.add (this);
     }
 
@@ -588,7 +591,7 @@ public:
 
             if (getHostType().isAbletonLive()
                  && hostCallback != nullptr
-                 && processor->getTailLengthSeconds() == std::numeric_limits<double>::max())
+                 && processor->getTailLengthSeconds() == std::numeric_limits<double>::infinity())
             {
                 AbletonLiveHostSpecific hostCmd;
 
@@ -2046,7 +2049,18 @@ private:
     pointer_sized_int handleGetTailSize (VstOpCodeArguments)
     {
         if (processor != nullptr)
-            return (pointer_sized_int) (processor->getTailLengthSeconds() * sampleRate);
+        {
+            int32 result;
+
+            auto tailSeconds = processor->getTailLengthSeconds();
+
+            if (tailSeconds == std::numeric_limits<double>::infinity())
+                result = std::numeric_limits<int32>::max();
+            else
+                result = static_cast<int32> (tailSeconds * sampleRate);
+
+            return result; // Vst2 expects an int32 upcasted to a intptr_t here
+        }
 
         return 0;
     }

modules/juce_audio_plugin_client/VST3/juce_VST3_Wrapper.cpp

@@ -2033,6 +2033,9 @@ public:
         if (tailLengthSeconds <= 0.0 || processSetup.sampleRate <= 0.0)
             return Vst::kNoTail;
 
+        if (tailLengthSeconds == std::numeric_limits<double>::infinity())
+            return Vst::kInfiniteTail;
+
         return (Steinberg::uint32) roundToIntAccurate (tailLengthSeconds * processSetup.sampleRate);
     }
 

modules/juce_audio_processors/format_types/juce_VST3PluginFormat.cpp

@@ -2296,7 +2296,14 @@ struct VST3PluginInstance : public AudioPluginInstance
             auto sampleRate = getSampleRate();
 
             if (sampleRate > 0.0)
+            {
+                auto tailSamples = processor->getTailSamples();
+
+                if (tailSamples == Vst::kInfiniteTail)
+                    return std::numeric_limits<double>::infinity();
+
                 return jlimit (0, 0x7fffffff, (int) processor->getTailSamples()) / sampleRate;
+            }
         }
 
         return 0.0;

modules/juce_audio_processors/format_types/juce_VSTInterface.h

@@ -83,11 +83,12 @@ typedef pointer_sized_int (VSTINTERFACECALL* VstHostCallback) (VstEffectInterfac
 
 enum VstEffectInterfaceFlags
 {
-    vstEffectFlagHasEditor          = 1,
-    vstEffectFlagInplaceAudio       = 16,
-    vstEffectFlagDataInChunks       = 32,
-    vstEffectFlagIsSynth            = 256,
-    vstEffectFlagInplaceDoubleAudio = 4096
+    vstEffectFlagHasEditor                   = 1,
+    vstEffectFlagInplaceAudio                = 16,
+    vstEffectFlagDataInChunks                = 32,
+    vstEffectFlagIsSynth                     = 256,
+    vstEffectFlagSilenceInProducesSilenceOut = 512,
+    vstEffectFlagInplaceDoubleAudio          = 4096
 };
 
 //==============================================================================

modules/juce_audio_processors/format_types/juce_VSTPluginFormat.cpp

@@ -1283,12 +1283,23 @@ struct VSTPluginInstance     : public AudioPluginInstance,
         if (vstEffect == nullptr)
             return 0.0;
 
-        auto sampleRate = getSampleRate();
-
-        if (sampleRate <= 0)
+        if ((vstEffect->flags & vstEffectFlagSilenceInProducesSilenceOut) != 0)
             return 0.0;
 
-        return dispatch (plugInOpcodeGetTailSize, 0, 0, 0, 0) / sampleRate;
+        auto tailSize = dispatch (plugInOpcodeGetTailSize, 0, 0, 0, 0);
+        auto sampleRate = getSampleRate();
+
+        // remain backward compatible with old JUCE plug-ins: anything larger
+        // than INT32_MAX is an invalid tail time but old JUCE 64-bit plug-ins
+        // would return INT64_MAX for infinite tail time. So treat anything
+        // equal or greater than INT32_MAX as infinite tail time.
+        if (tailSize >= std::numeric_limits<int32>::max())
+            return std::numeric_limits<double>::infinity();
+
+        if (tailSize >= 0 && sampleRate > 0)
+            return static_cast<double> (tailSize) / sampleRate;
+
+        return 0.0;
     }
 
     bool acceptsMidi() const override    { return wantsMidiMessages; }