bug 1199559 write audioprocess input buffer in a format suitable for direct use by AudioBuffer r=padenot

saving copying.

This also avoids graph thread allocations when input is null.

--HG--
extra : rebase_source : f9d2d987076fd23ecf2ff37ab0008ef7eb50a278

dom/media/webaudio/ScriptProcessorNode.cpp

@@ -240,8 +240,6 @@ private:
 class ScriptProcessorNodeEngine final : public AudioNodeEngine
 {
 public:
-  typedef nsAutoTArray<nsAutoArrayPtr<float>, 2> InputChannels;
-
   ScriptProcessorNodeEngine(ScriptProcessorNode* aNode,
                             AudioDestinationNode* aDestination,
                             uint32_t aBufferSize,
@@ -250,11 +248,9 @@ public:
     , mSource(nullptr)
     , mDestination(aDestination->Stream())
     , mBufferSize(aBufferSize)
+    , mInputChannelCount(aNumberOfInputChannels)
     , mInputWriteIndex(0)
-    , mSeenNonSilenceInput(false)
   {
-    mInputChannels.SetLength(aNumberOfInputChannels);
-    AllocateInputBlock();
   }
 
   void SetSourceStream(AudioNodeStream* aSource)
@@ -294,23 +290,34 @@ public:
     if (!mIsConnected) {
       aOutput->SetNull(WEBAUDIO_BLOCK_SIZE);
       mSharedBuffers->Reset();
-      mSeenNonSilenceInput = false;
       mInputWriteIndex = 0;
       return;
     }
 
-    // First, record our input buffer
-    for (uint32_t i = 0; i < mInputChannels.Length(); ++i) {
+    // The input buffer is allocated lazily when non-null input is received.
+    if (!aInput.IsNull() && !mInputBuffer) {
+      mInputBuffer = ThreadSharedFloatArrayBufferList::
+        Create(mInputChannelCount, mBufferSize, fallible);
+      if (mInputBuffer && mInputWriteIndex) {
+        // Zero leading for null chunks that were skipped.
+        for (uint32_t i = 0; i < mInputChannelCount; ++i) {
+          float* channelData = mInputBuffer->GetDataForWrite(i);
+          PodZero(channelData, mInputWriteIndex);
+        }
+      }
+    }
+
+    // First, record our input buffer, if its allocation succeeded.
+    uint32_t inputChannelCount = mInputBuffer ? mInputBuffer->GetChannels() : 0;
+    for (uint32_t i = 0; i < inputChannelCount; ++i) {
+      float* writeData = mInputBuffer->GetDataForWrite(i) + mInputWriteIndex;
       if (aInput.IsNull()) {
-        PodZero(mInputChannels[i] + mInputWriteIndex,
-                aInput.GetDuration());
+        PodZero(writeData, aInput.GetDuration());
       } else {
-        mSeenNonSilenceInput = true;
         MOZ_ASSERT(aInput.GetDuration() == WEBAUDIO_BLOCK_SIZE, "sanity check");
-        MOZ_ASSERT(aInput.mChannelData.Length() == mInputChannels.Length());
+        MOZ_ASSERT(aInput.mChannelData.Length() == inputChannelCount);
         AudioBlockCopyChannelWithScale(static_cast<const float*>(aInput.mChannelData[i]),
-                                       aInput.mVolume,
-                                       mInputChannels[i] + mInputWriteIndex);
+                                       aInput.mVolume, writeData);
       }
     }
     mInputWriteIndex += aInput.GetDuration();
@@ -323,8 +330,6 @@ public:
     if (mInputWriteIndex >= mBufferSize) {
       SendBuffersToMainThread(aStream);
       mInputWriteIndex -= mBufferSize;
-      mSeenNonSilenceInput = false;
-      AllocateInputBlock();
     }
   }
 
@@ -335,10 +340,7 @@ public:
     // - mDestination (probably)
     size_t amount = AudioNodeEngine::SizeOfExcludingThis(aMallocSizeOf);
     amount += mSharedBuffers->SizeOfIncludingThis(aMallocSizeOf);
-    amount += mInputChannels.ShallowSizeOfExcludingThis(aMallocSizeOf);
-    for (size_t i = 0; i < mInputChannels.Length(); i++) {
-      amount += mInputChannels[i].SizeOfExcludingThis(aMallocSizeOf);
-    }
+    amount += mInputBuffer->SizeOfIncludingThis(aMallocSizeOf);
 
     return amount;
   }
@@ -349,15 +351,6 @@ public:
   }
 
 private:
-  void AllocateInputBlock()
-  {
-    for (unsigned i = 0; i < mInputChannels.Length(); ++i) {
-      if (!mInputChannels[i]) {
-        mInputChannels[i] = new float[mBufferSize];
-      }
-    }
-  }
-
   void SendBuffersToMainThread(AudioNodeStream* aStream)
   {
     MOZ_ASSERT(!NS_IsMainThread());
@@ -376,19 +369,12 @@ private:
     {
     public:
       Command(AudioNodeStream* aStream,
-              InputChannels& aInputChannels,
-              double aPlaybackTime,
-              bool aNullInput)
+              already_AddRefed<ThreadSharedFloatArrayBufferList> aInputBuffer,
+              double aPlaybackTime)
         : mStream(aStream)
+        , mInputBuffer(aInputBuffer)
         , mPlaybackTime(aPlaybackTime)
-        , mNullInput(aNullInput)
       {
-        mInputChannels.SetLength(aInputChannels.Length());
-        if (!aNullInput) {
-          for (uint32_t i = 0; i < mInputChannels.Length(); ++i) {
-            mInputChannels[i] = aInputChannels[i].forget();
-          }
-        }
       }
 
       NS_IMETHOD Run() override
@@ -431,22 +417,19 @@ private:
           return nullptr;
         }
         JSContext* cx = jsapi.cx();
+        uint32_t inputChannelCount = aNode->ChannelCount();
 
         // Create the input buffer
         nsRefPtr<AudioBuffer> inputBuffer;
-        if (!mNullInput) {
+        if (mInputBuffer) {
           ErrorResult rv;
           inputBuffer =
-            AudioBuffer::Create(context, mInputChannels.Length(),
-                                aNode->BufferSize(),
-                                context->SampleRate(), cx, rv);
+            AudioBuffer::Create(context, inputChannelCount,
+                                aNode->BufferSize(), context->SampleRate(),
+                                mInputBuffer.forget(), cx, rv);
           if (rv.Failed()) {
             return nullptr;
           }
-          // Put the channel data inside it
-          for (uint32_t i = 0; i < mInputChannels.Length(); ++i) {
-            inputBuffer->SetRawChannelContents(i, mInputChannels[i]);
-          }
         }
 
         // Ask content to produce data in the output buffer
@@ -457,7 +440,7 @@ private:
         nsRefPtr<AudioProcessingEvent> event =
           new AudioProcessingEvent(aNode, nullptr, nullptr);
         event->InitEvent(inputBuffer,
-                         mInputChannels.Length(),
+                         inputChannelCount,
                          context->StreamTimeToDOMTime(mPlaybackTime));
         aNode->DispatchTrustedEvent(event);
 
@@ -478,14 +461,12 @@ private:
       }
     private:
       nsRefPtr<AudioNodeStream> mStream;
-      InputChannels mInputChannels;
+      nsRefPtr<ThreadSharedFloatArrayBufferList> mInputBuffer;
       double mPlaybackTime;
-      bool mNullInput;
     };
 
-    NS_DispatchToMainThread(new Command(aStream, mInputChannels,
-                                        playbackTime,
-                                        !mSeenNonSilenceInput));
+    NS_DispatchToMainThread(new Command(aStream, mInputBuffer.forget(),
+                                        playbackTime));
   }
 
   friend class ScriptProcessorNode;
@@ -493,12 +474,12 @@ private:
   nsAutoPtr<SharedBuffers> mSharedBuffers;
   AudioNodeStream* mSource;
   AudioNodeStream* mDestination;
-  InputChannels mInputChannels;
+  nsRefPtr<ThreadSharedFloatArrayBufferList> mInputBuffer;
   const uint32_t mBufferSize;
+  const uint32_t mInputChannelCount;
   // The write index into the current input buffer
   uint32_t mInputWriteIndex;
   bool mIsConnected = false;
-  bool mSeenNonSilenceInput;
 };
 
 ScriptProcessorNode::ScriptProcessorNode(AudioContext* aContext,