1 files changed, 94 insertions, 0 deletions
diff --git a/dom/media/platforms/agnostic/bytestreams/Adts.cpp b/dom/media/platforms/agnostic/bytestreams/Adts.cpp
new file mode 100644
index 0000000000..5f31904d9c
--- /dev/null
+++ b/dom/media/platforms/agnostic/bytestreams/Adts.cpp
@@ -0,0 +1,94 @@
+/* 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 "Adts.h"
+#include "MediaData.h"
+#include "mozilla/Array.h"
+#include "mozilla/ArrayUtils.h"
+
+namespace mozilla {
+
+static const int kADTSHeaderSize = 7;
+
+int8_t Adts::GetFrequencyIndex(uint32_t aSamplesPerSecond) {
+  static const uint32_t freq_lookup[] = {96000, 88200, 64000, 48000, 44100,
+                                         32000, 24000, 22050, 16000, 12000,
+                                         11025, 8000,  7350,  0};
+
+  int8_t i = 0;
+  while (freq_lookup[i] && aSamplesPerSecond < freq_lookup[i]) {
+    i++;
+  }
+
+  if (!freq_lookup[i]) {
+    return -1;
+  }
+
+  return i;
+}
+
+bool Adts::ConvertSample(uint16_t aChannelCount, int8_t aFrequencyIndex,
+                         int8_t aProfile, MediaRawData* aSample) {
+  size_t newSize = aSample->Size() + kADTSHeaderSize;
+
+  // ADTS header uses 13 bits for packet size.
+  if (newSize >= (1 << 13) || aChannelCount > 15 || aFrequencyIndex < 0 ||
+      aProfile < 1 || aProfile > 4) {
+    return false;
+  }
+
+  Array<uint8_t, kADTSHeaderSize> header;
+  header[0] = 0xff;
+  header[1] = 0xf1;
+  header[2] =
+      ((aProfile - 1) << 6) + (aFrequencyIndex << 2) + (aChannelCount >> 2);
+  header[3] = ((aChannelCount & 0x3) << 6) + (newSize >> 11);
+  header[4] = (newSize & 0x7ff) >> 3;
+  header[5] = ((newSize & 7) << 5) + 0x1f;
+  header[6] = 0xfc;
+
+  UniquePtr<MediaRawDataWriter> writer(aSample->CreateWriter());
+  if (!writer->Prepend(&header[0], ArrayLength(header))) {
+    return false;
+  }
+
+  if (aSample->mCrypto.IsEncrypted()) {
+    if (aSample->mCrypto.mPlainSizes.Length() == 0) {
+      writer->mCrypto.mPlainSizes.AppendElement(kADTSHeaderSize);
+      writer->mCrypto.mEncryptedSizes.AppendElement(aSample->Size() -
+                                                    kADTSHeaderSize);
+    } else {
+      writer->mCrypto.mPlainSizes[0] += kADTSHeaderSize;
+    }
+  }
+
+  return true;
+}
+
+bool Adts::RevertSample(MediaRawData* aSample) {
+  if (aSample->Size() < kADTSHeaderSize) {
+    return false;
+  }
+
+  {
+    const uint8_t* header = aSample->Data();
+    if (header[0] != 0xff || header[1] != 0xf1 || header[6] != 0xfc) {
+      // Not ADTS.
+      return false;
+    }
+  }
+
+  UniquePtr<MediaRawDataWriter> writer(aSample->CreateWriter());
+  writer->PopFront(kADTSHeaderSize);
+
+  if (aSample->mCrypto.IsEncrypted()) {
+    if (aSample->mCrypto.mPlainSizes.Length() > 0 &&
+        writer->mCrypto.mPlainSizes[0] >= kADTSHeaderSize) {
+      writer->mCrypto.mPlainSizes[0] -= kADTSHeaderSize;
+    }
+  }
+
+  return true;
+}
+}  // namespace mozilla