Racks: Fixed an issue that meant Racks with Modifiers would get their inputs passed through to their outputs

Author: drowaudio

modules/tracktion_engine/model/automation/tracktion_Modifier.cpp

@@ -171,6 +171,7 @@ void Modifier::baseClassDeinitialise()
 void Modifier::baseClassApplyToBuffer (const PluginRenderContext& prc)
 {
     applyToBuffer (prc);
+
     jassert (valueFifo);
     const float v = getCurrentValue();
     valueFifo->addValue (prc.bufferNumSamples, getCurrentValue());

modules/tracktion_engine/playback/graph/tracktion_EditNodeBuilder.cpp

@@ -1334,7 +1334,8 @@ std::unique_ptr<tracktion::graph::Node> createModifierNodeForList (ModifierList*
                 continue;
 
             node = makeNode<ModifierNode> (std::move (node), modifier, params.sampleRate, params.blockSize,
-                                           trackMuteState, playHeadState, params.forRendering);
+                                           trackMuteState, playHeadState, params.forRendering,
+                                           ModifierNode::ClearOutputs::no);
         }
     }
 

modules/tracktion_engine/playback/graph/tracktion_ModifierNode.cpp

@@ -18,12 +18,14 @@ ModifierNode::ModifierNode (std::unique_ptr<Node> inputNode,
                             tracktion::engine::Modifier::Ptr modifierToProcess,
                             double sampleRateToUse, int blockSizeToUse,
                             const TrackMuteState* trackMuteStateToUse,
-                            tracktion::graph::PlayHeadState& playHeadStateToUse, bool rendering)
+                            tracktion::graph::PlayHeadState& playHeadStateToUse,
+                            bool rendering, ClearOutputs clearOutputs_)
     : input (std::move (inputNode)),
       modifier (std::move (modifierToProcess)),
       trackMuteState (trackMuteStateToUse),
       playHeadState (&playHeadStateToUse),
-      isRendering (rendering)
+      isRendering (rendering),
+      clearOutputs (clearOutputs_)
 {
     jassert (input != nullptr);
     jassert (modifier != nullptr);
@@ -116,8 +118,15 @@ void ModifierNode::process (ProcessContext& pc)
     if (shouldProcess)
         modifier->baseClassApplyToBuffer (getPluginRenderContext (pc.referenceSampleRange, outputAudioBuffer));
 
-    // Then copy the buffers to the outputs
-    outputBuffers.midi.copyFrom (midiMessageArray);
+    if (clearOutputs == ClearOutputs::yes)
+    {
+        outputAudioBlock.clear();
+    }
+    else
+    {
+        // Then copy the buffers to the outputs
+        outputBuffers.midi.copyFrom (midiMessageArray);
+    }
 }
 
 //==============================================================================

modules/tracktion_engine/playback/graph/tracktion_ModifierNode.h

@@ -22,17 +22,26 @@ class ModifierNode final    : public tracktion::graph::Node
 {
 public:
     //==============================================================================
+    enum class ClearOutputs : bool
+    {
+        no,
+        yes
+    };
+
     /** Creates a ModifierNode to process a Modifier.
         @param const TrackMuteState*    The optional TrackMuteState to use
         @param PlayHeadState            The PlayHeadState to monitor for jumps
         @param rendering                Should be true if this is an offline render
+        @param ClearOutputs             Whether to clear the outputs or pass them through
 
     */
     ModifierNode (std::unique_ptr<Node> input,
                   tracktion::engine::Modifier::Ptr,
                   double sampleRateToUse, int blockSizeToUse,
                   const TrackMuteState*,
-                  tracktion::graph::PlayHeadState&, bool rendering);
+                  tracktion::graph::PlayHeadState&,
+                  bool rendering,
+                  ClearOutputs);
 
     /** Creates a ModifierNode to process a plugin on in a Rack with an InputProvider.
         @param InputProvider            The InputProvider to provide inputs and a PluginRenderContext
@@ -65,6 +74,7 @@ class ModifierNode final    : public tracktion::graph::Node
     const TrackMuteState* trackMuteState = nullptr;
     tracktion::graph::PlayHeadState* playHeadState = nullptr;
     bool isRendering = false;
+    ClearOutputs clearOutputs = ClearOutputs::no;
 
     bool isInitialised = false;
     double sampleRate = 44100.0;

modules/tracktion_engine/playback/graph/tracktion_RackNode.cpp

@@ -401,7 +401,8 @@ namespace RackNodeBuilder
         for (auto m : rack.getModifierList().getModifiers())
             itemNodes[m->itemID] = makeNode<ModifierNode> (makeNode<ConnectedNode> ((size_t) m->itemID.getRawID()),
                                                            m, sampleRate, blockSize, nullptr,
-                                                           processState.playHeadState, isRendering);
+                                                           processState.playHeadState, isRendering,
+                                                           ModifierNode::ClearOutputs::yes);
 
         // Create an input node and an output summing node
         auto outputNode = std::make_unique<ConnectedNode>();

modules/tracktion_engine/plugins/tracktion_Plugins.test.cpp

@@ -363,6 +363,51 @@ class ModifiedParameterValuesTests  : public juce::UnitTest
 
 static ModifiedParameterValuesTests modifiedParameterValuesTests;
 
+
+//==============================================================================
+//==============================================================================
+TEST_SUITE ("tracktion_engine")
+{
+    TEST_CASE ("Modifiers in Racks")
+    {
+        // Add a Modifier to a Rack and ensure the input isn't present on the output
+        auto& engine = *Engine::getEngines()[0];
+        auto edit = engine::test_utilities::createTestEdit (engine, 1, Edit::forEditing);
+
+        auto rackType = edit->getRackList().addNewRack();
+        auto modifier = rackType->getModifierList().insertModifier (juce::ValueTree (IDs::ENVELOPEFOLLOWER), 0, nullptr);
+        CHECK(rackType->addConnection (EditItemID(), 1, modifier->itemID, 1));
+        CHECK(rackType->addConnection (EditItemID(), 2, modifier->itemID, 2));
+
+        auto& track = *getAudioTracks (*edit)[0];
+        auto fileLength = 5_td;
+        auto squareFile = graph::test_utilities::getSquareFile<juce::WavAudioFormat> (44100.0, fileLength.inSeconds());
+        auto squareAudioFile = AudioFile (engine, squareFile->getFile());
+        insertWaveClip (track, {}, squareFile->getFile(),
+                        ClipPosition {{ 0_tp, fileLength }}, DeleteExistingClips::no);
+
+        // Check square clip is audible
+        {
+            auto player = test_utilities::createEnginePlayer (*edit, {}, { squareAudioFile });
+            auto buffer = process (*player, fileLength);
+
+            CHECK_GT(getRMS (toBufferView (buffer).getChannel (0)), 0.99f);
+        }
+
+        // Now add Rack and clip shouldn't be heard
+        {
+            [[maybe_unused]] auto rackInstance = track.pluginList.insertPlugin (RackInstance::create (*rackType), 0);
+
+            edit->getTransport().setPosition (0_tp);
+            auto player = test_utilities::createEnginePlayer (*edit, {}, { squareAudioFile });
+            auto buffer = process (*player, fileLength);
+
+            CHECK_LT(getRMS (toBufferView (buffer).getChannel (0)), 0.01f);
+        }
+    }
+}
+
+
 #endif
 
 

modules/tracktion_engine/testing/tracktion_EnginePlayer.h

@@ -118,6 +118,14 @@ class EnginePlayer
     int numSamplesProcessed = 0;
 };
 
+//==============================================================================
+//==============================================================================
+/** Process a duration. */
+inline juce::AudioBuffer<float> process (EnginePlayer& player, TimeDuration td)
+{
+    auto numSamples = toSamples (td, player.getParams().sampleRate);
+    return player.process (numSamples);
+}
 
 //==============================================================================
 //==============================================================================

modules/tracktion_engine/utilities/tracktion_AudioUtilities.h

@@ -83,6 +83,10 @@ inline choc::buffer::BufferView<SampleType, choc::buffer::SeparateChannelLayout>
                                                  (choc::buffer::FrameCount) buffer.getNumSamples());
 }
 
+/** Returns the RMS of a single channel buffer. */
+template<typename SampleType>
+SampleType getRMS (choc::buffer::MonoView<SampleType>);
+
 //==============================================================================
 /** All laws have been designed to be equal-power, excluding linear respectively */
 enum PanLaw
@@ -255,6 +259,24 @@ inline void clearChannels (juce::AudioBuffer<float>& buffer, int startChannel, i
         buffer.clear (ch, startSample, endSample);
 }
 
+
+//==============================================================================
+template<typename SampleType>
+inline SampleType getRMS (choc::buffer::MonoView<SampleType> view)
+{
+    auto numSamples = view.getNumFrames();
+    double sum = 0.0;
+
+    for (choc::buffer::FrameCount i = 0; i < numSamples; ++i)
+    {
+        auto sample = view.getSample (0, i);
+        sum += sample * sample;
+    }
+
+    return static_cast<SampleType> (std::sqrt (sum / numSamples));
+}
+
+
 }} // namespace tracktion { inline namespace engine
 
 namespace juce