Add HE AAC support to ISO BMFF.

content/common/gpu/media/h264_bit_reader.cc

Index: content/common/gpu/media/h264_bit_reader.cc
diff --git a/content/common/gpu/media/h264_bit_reader.cc b/content/common/gpu/media/h264_bit_reader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b8d00e174a33ef36461c82dfc34b4046dc3f6fd5
--- /dev/null
+++ b/content/common/gpu/media/h264_bit_reader.cc
@@ -0,0 +1,45 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/common/gpu/media/h264_bit_reader.h"
+
+namespace content {
+
+H264BitReader::H264BitReader() {
+}
+
+H264BitReader::~H264BitReader() {}
+
+void H264BitReader::UpdateCurrByte() {
+  DCHECK_EQ(num_remaining_bits_in_curr_byte_, 0);
+
+  if (bytes_left_ >= 1) {
+    // Emulation prevention three-byte detection.
+    // If a sequence of 0x000003 is found, skip (ignore) the last byte (0x03).
+    if (*data_ == 0x03 && Tell() >= 16 && data_[-1] == 0 && data_[-2] == 0) {
+      // Detected 0x000003, skip last byte.
+      ++data_;
+      --bytes_left_;
+      position_ += 8;
+    }
+  }
+
+  if (bytes_left_ >= 1) {
+    // Load a new byte and advance pointers.
+    curr_byte_ = *data_;
+    ++data_;
+    --bytes_left_;
+    num_remaining_bits_in_curr_byte_ = 8;
+  }
+
+  // Check if this is the end of RBSP data.
+  if (bytes_left_ == 0) {
+    while (num_remaining_bits_in_curr_byte_ != 0 && !(curr_byte_ & 0x1)) {
+      --num_remaining_bits_in_curr_byte_;
+      curr_byte_ >>= 1;
+    }

[Pawel Osciak, 2012/07/16 21:27:09]

This is not true. There can be more than one zero-byte padding in the stream, so
this will not always work.
Also, we need to use HasMoreRBSPData() only at specific situations and doing
this every byte is suboptimal (and also incorrect).

[Pawel Osciak, 2012/07/16 21:30:57]

Sorry, meant every last byte.

+  }
+}
+
+}  // namespace content