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

saving a copy.

--HG--
extra : rebase_source : e3d477c46ca365f0d65b47355b5ecf42d81a056b

dom/media/webaudio/AudioDestinationNode.cpp

@@ -32,8 +32,6 @@ static uint8_t gWebAudioOutputKey;
 class OfflineDestinationNodeEngine final : public AudioNodeEngine
 {
 public:
-  typedef AutoFallibleTArray<nsAutoArrayPtr<float>, 2> InputChannels;
-
   OfflineDestinationNodeEngine(AudioDestinationNode* aNode,
                                uint32_t aNumberOfChannels,
                                uint32_t aLength,
@@ -61,21 +59,14 @@ public:
       // These allocations might fail if content provides a huge number of
       // channels or size, but it's OK since we'll deal with the failure
       // gracefully.
-      if (mInputChannels.SetLength(mNumberOfChannels, fallible)) {
-        for (uint32_t i = 0; i < mNumberOfChannels; ++i) {
-          mInputChannels[i] = new (fallible) float[mLength];
-          if (!mInputChannels[i]) {
-            mInputChannels.Clear();
-            break;
-          }
-        }
-      }
+      mBuffer = ThreadSharedFloatArrayBufferList::
+        Create(mNumberOfChannels, mLength, fallible);
 
       mBufferAllocated = true;
     }
 
     // Handle the case of allocation failure in the input buffer
-    if (mInputChannels.IsEmpty()) {
+    if (mBuffer) {
       return;
     }
 
@@ -88,33 +79,28 @@ public:
     // Record our input buffer
     MOZ_ASSERT(mWriteIndex < mLength, "How did this happen?");
     const uint32_t duration = std::min(WEBAUDIO_BLOCK_SIZE, mLength - mWriteIndex);
-    const uint32_t commonChannelCount = std::min(mInputChannels.Length(),
-                                                 aInput.mChannelData.Length());
-    // First, copy as many channels in the input as we have
-    for (uint32_t i = 0; i < commonChannelCount; ++i) {
-      if (aInput.IsNull()) {
-        PodZero(mInputChannels[i] + mWriteIndex, duration);
+    const uint32_t inputChannelCount = aInput.mChannelData.Length();
+    for (uint32_t i = 0; i < mNumberOfChannels; ++i) {
+      float* outputData = mBuffer->GetDataForWrite(i) + mWriteIndex;
+      if (aInput.IsNull() || i >= inputChannelCount) {
+        PodZero(outputData, duration);
       } else {
         const float* inputBuffer = static_cast<const float*>(aInput.mChannelData[i]);
         if (duration == WEBAUDIO_BLOCK_SIZE) {
           // Use the optimized version of the copy with scale operation
           AudioBlockCopyChannelWithScale(inputBuffer, aInput.mVolume,
-                                         mInputChannels[i] + mWriteIndex);
+                                         outputData);
         } else {
           if (aInput.mVolume == 1.0f) {
-            PodCopy(mInputChannels[i] + mWriteIndex, inputBuffer, duration);
+            PodCopy(outputData, inputBuffer, duration);
           } else {
             for (uint32_t j = 0; j < duration; ++j) {
-              mInputChannels[i][mWriteIndex + j] = aInput.mVolume * inputBuffer[j];
+              outputData[j] = aInput.mVolume * inputBuffer[j];
             }
           }
         }
       }
     }
-    // Then, silence all of the remaining channels
-    for (uint32_t i = commonChannelCount; i < mInputChannels.Length(); ++i) {
-      PodZero(mInputChannels[i] + mWriteIndex, duration);
-    }
     mWriteIndex += duration;
 
     if (mWriteIndex >= mLength) {
@@ -165,14 +151,11 @@ public:
     // Create the input buffer
     ErrorResult rv;
     nsRefPtr<AudioBuffer> renderedBuffer =
-      AudioBuffer::Create(context, mInputChannels.Length(),
-                          mLength, mSampleRate, cx, rv);
+      AudioBuffer::Create(context, mNumberOfChannels, mLength, mSampleRate,
+                          mBuffer.forget(), cx, rv);
     if (rv.Failed()) {
       return;
     }
-    for (uint32_t i = 0; i < mInputChannels.Length(); ++i) {
-      renderedBuffer->SetRawChannelContents(i, mInputChannels[i]);
-    }
 
     aNode->ResolvePromise(renderedBuffer);
 
@@ -186,7 +169,7 @@ public:
   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
   {
     size_t amount = AudioNodeEngine::SizeOfExcludingThis(aMallocSizeOf);
-    amount += mInputChannels.ShallowSizeOfExcludingThis(aMallocSizeOf);
+    amount += mBuffer->SizeOfIncludingThis(aMallocSizeOf);
     return amount;
   }
 
@@ -196,11 +179,11 @@ public:
   }
 
 private:
-  // The input to the destination node is recorded in the mInputChannels buffer.
+  // The input to the destination node is recorded in mBuffer.
   // When this buffer fills up with mLength frames, the buffered input is sent
   // to the main thread in order to dispatch OfflineAudioCompletionEvent.
-  InputChannels mInputChannels;
-  // An index representing the next offset in mInputChannels to be written to.
+  nsRefPtr<ThreadSharedFloatArrayBufferList> mBuffer;
+  // An index representing the next offset in mBuffer to be written to.
   uint32_t mWriteIndex;
   uint32_t mNumberOfChannels;
   // How many frames the OfflineAudioContext intends to produce.