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-rw-r--r--dom/media/AudioCompactor.cpp73
1 files changed, 73 insertions, 0 deletions
diff --git a/dom/media/AudioCompactor.cpp b/dom/media/AudioCompactor.cpp
new file mode 100644
index 000000000..6ffbc966f
--- /dev/null
+++ b/dom/media/AudioCompactor.cpp
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 "AudioCompactor.h"
+#if defined(MOZ_MEMORY)
+# include "mozmemory.h"
+#endif
+
+namespace mozilla {
+
+static size_t
+MallocGoodSize(size_t aSize)
+{
+# if defined(MOZ_MEMORY)
+ return malloc_good_size(aSize);
+# else
+ return aSize;
+# endif
+}
+
+static size_t
+TooMuchSlop(size_t aSize, size_t aAllocSize, size_t aMaxSlop)
+{
+ // If the allocated size is less then our target size, then we
+ // are chunking. This means it will be completely filled with
+ // zero slop.
+ size_t slop = (aAllocSize > aSize) ? (aAllocSize - aSize) : 0;
+ return slop > aMaxSlop;
+}
+
+uint32_t
+AudioCompactor::GetChunkSamples(uint32_t aFrames, uint32_t aChannels,
+ size_t aMaxSlop)
+{
+ size_t size = AudioDataSize(aFrames, aChannels);
+ size_t chunkSize = MallocGoodSize(size);
+
+ // Reduce the chunk size until we meet our slop goal or the chunk
+ // approaches an unreasonably small size.
+ while (chunkSize > 64 && TooMuchSlop(size, chunkSize, aMaxSlop)) {
+ chunkSize = MallocGoodSize(chunkSize / 2);
+ }
+
+ // Calculate the number of samples based on expected malloc size
+ // in order to allow as many frames as possible to be packed.
+ return chunkSize / sizeof(AudioDataValue);
+}
+
+uint32_t
+AudioCompactor::NativeCopy::operator()(AudioDataValue *aBuffer,
+ uint32_t aSamples)
+{
+ NS_ASSERTION(aBuffer, "cannot copy to null buffer pointer");
+ NS_ASSERTION(aSamples, "cannot copy zero values");
+
+ size_t bufferBytes = aSamples * sizeof(AudioDataValue);
+ size_t maxBytes = std::min(bufferBytes, mSourceBytes - mNextByte);
+ uint32_t frames = maxBytes / BytesPerFrame(mChannels);
+ size_t bytes = frames * BytesPerFrame(mChannels);
+
+ NS_ASSERTION((mNextByte + bytes) <= mSourceBytes,
+ "tried to copy beyond source buffer");
+ NS_ASSERTION(bytes <= bufferBytes, "tried to copy beyond destination buffer");
+
+ memcpy(aBuffer, mSource + mNextByte, bytes);
+
+ mNextByte += bytes;
+ return frames;
+}
+
+} // namespace mozilla