1 files changed, 149 insertions, 0 deletions
diff --git a/dom/media/webaudio/GainNode.cpp b/dom/media/webaudio/GainNode.cpp
new file mode 100644
index 0000000000..c858497353
--- /dev/null
+++ b/dom/media/webaudio/GainNode.cpp
@@ -0,0 +1,149 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GainNode.h"
+#include "mozilla/dom/GainNodeBinding.h"
+#include "AlignmentUtils.h"
+#include "AudioNodeEngine.h"
+#include "AudioNodeTrack.h"
+#include "AudioDestinationNode.h"
+#include "WebAudioUtils.h"
+#include "Tracing.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(GainNode, AudioNode, mGain)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(GainNode)
+NS_INTERFACE_MAP_END_INHERITING(AudioNode)
+
+NS_IMPL_ADDREF_INHERITED(GainNode, AudioNode)
+NS_IMPL_RELEASE_INHERITED(GainNode, AudioNode)
+
+class GainNodeEngine final : public AudioNodeEngine {
+ public:
+  GainNodeEngine(AudioNode* aNode, AudioDestinationNode* aDestination)
+      : AudioNodeEngine(aNode),
+        mDestination(aDestination->Track())
+        // Keep the default value in sync with the default value in
+        // GainNode::GainNode.
+        ,
+        mGain(1.f) {}
+
+  enum Parameters { GAIN };
+  void RecvTimelineEvent(uint32_t aIndex, AudioTimelineEvent& aEvent) override {
+    MOZ_ASSERT(mDestination);
+    WebAudioUtils::ConvertAudioTimelineEventToTicks(aEvent, mDestination);
+
+    switch (aIndex) {
+      case GAIN:
+        mGain.InsertEvent<int64_t>(aEvent);
+        break;
+      default:
+        NS_ERROR("Bad GainNodeEngine TimelineParameter");
+    }
+  }
+
+  void ProcessBlock(AudioNodeTrack* aTrack, GraphTime aFrom,
+                    const AudioBlock& aInput, AudioBlock* aOutput,
+                    bool* aFinished) override {
+    TRACE("GainNodeEngine::ProcessBlock");
+    if (aInput.IsNull()) {
+      // If input is silent, so is the output
+      aOutput->SetNull(WEBAUDIO_BLOCK_SIZE);
+    } else if (mGain.HasSimpleValue()) {
+      // Optimize the case where we only have a single value set as the volume
+      float gain = mGain.GetValue();
+      if (gain == 0.0f) {
+        aOutput->SetNull(WEBAUDIO_BLOCK_SIZE);
+      } else {
+        *aOutput = aInput;
+        aOutput->mVolume *= gain;
+      }
+    } else {
+      // First, compute a vector of gains for each track tick based on the
+      // timeline at hand, and then for each channel, multiply the values
+      // in the buffer with the gain vector.
+      aOutput->AllocateChannels(aInput.ChannelCount());
+
+      // Compute the gain values for the duration of the input AudioChunk
+      TrackTime tick = mDestination->GraphTimeToTrackTime(aFrom);
+      float computedGain[WEBAUDIO_BLOCK_SIZE + 4];
+      float* alignedComputedGain = ALIGNED16(computedGain);
+      ASSERT_ALIGNED16(alignedComputedGain);
+      mGain.GetValuesAtTime(tick, alignedComputedGain, WEBAUDIO_BLOCK_SIZE);
+
+      for (size_t counter = 0; counter < WEBAUDIO_BLOCK_SIZE; ++counter) {
+        alignedComputedGain[counter] *= aInput.mVolume;
+      }
+
+      // Apply the gain to the output buffer
+      for (size_t channel = 0; channel < aOutput->ChannelCount(); ++channel) {
+        const float* inputBuffer =
+            static_cast<const float*>(aInput.mChannelData[channel]);
+        float* buffer = aOutput->ChannelFloatsForWrite(channel);
+        AudioBlockCopyChannelWithScale(inputBuffer, alignedComputedGain,
+                                       buffer);
+      }
+    }
+  }
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override {
+    // Not owned:
+    // - mDestination - MediaTrackGraphImpl::CollectSizesForMemoryReport()
+    // accounts for mDestination.
+    // - mGain - Internal ref owned by AudioNode
+    return AudioNodeEngine::SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  RefPtr<AudioNodeTrack> mDestination;
+  AudioParamTimeline mGain;
+};
+
+GainNode::GainNode(AudioContext* aContext)
+    : AudioNode(aContext, 2, ChannelCountMode::Max,
+                ChannelInterpretation::Speakers) {
+  mGain = CreateAudioParam(GainNodeEngine::GAIN, u"gain"_ns, 1.0f);
+  GainNodeEngine* engine = new GainNodeEngine(this, aContext->Destination());
+  mTrack = AudioNodeTrack::Create(
+      aContext, engine, AudioNodeTrack::NO_TRACK_FLAGS, aContext->Graph());
+}
+
+/* static */
+already_AddRefed<GainNode> GainNode::Create(AudioContext& aAudioContext,
+                                            const GainOptions& aOptions,
+                                            ErrorResult& aRv) {
+  RefPtr<GainNode> audioNode = new GainNode(&aAudioContext);
+
+  audioNode->Initialize(aOptions, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  audioNode->Gain()->SetInitialValue(aOptions.mGain);
+  return audioNode.forget();
+}
+
+size_t GainNode::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+  size_t amount = AudioNode::SizeOfExcludingThis(aMallocSizeOf);
+  amount += mGain->SizeOfIncludingThis(aMallocSizeOf);
+  return amount;
+}
+
+size_t GainNode::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
+  return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+}
+
+JSObject* GainNode::WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) {
+  return GainNode_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+}  // namespace mozilla::dom