Add HE AAC support to ISO BMFF.

content/common/gpu/media/h264_parser.cc

Index: content/common/gpu/media/h264_parser.cc
diff --git a/content/common/gpu/media/h264_parser.cc b/content/common/gpu/media/h264_parser.cc
index ace3dabed033c7991c6d747c35c8226b530a0541..912b877acdbeb32360656615d3ab6b10ca087234 100644
--- a/content/common/gpu/media/h264_parser.cc
+++ b/content/common/gpu/media/h264_parser.cc
@@ -50,101 +50,40 @@ H264SEIMessage::H264SEIMessage() {
   memset(this, 0, sizeof(*this));
 }
 
-H264Parser::H264BitReader::H264BitReader()
-    : data_(NULL),
-      bytes_left_(0),
-      curr_byte_(0),
-      num_remaining_bits_in_curr_byte_(0),
-      prev_two_bytes_(0) {
+H264Parser::H264BitReader::H264BitReader() {
 }
 
 H264Parser::H264BitReader::~H264BitReader() {}
 
-bool H264Parser::H264BitReader::Initialize(const uint8* data, off_t size) {
-  DCHECK(data);
-
-  if (size < 1)
-    return false;
-
-  data_ = data;
-  bytes_left_ = size;
-  num_remaining_bits_in_curr_byte_ = 0;
-  // Initially set to 0xffff to accept all initial two-byte sequences.
-  prev_two_bytes_ = 0xffff;
-
-  return true;
-}
-
-bool H264Parser::H264BitReader::UpdateCurrByte() {
-  if (bytes_left_ < 1)
-    return false;
+void H264Parser::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;
+    }
+  }
 
-  // Emulation prevention three-byte detection.
-  // If a sequence of 0x000003 is found, skip (ignore) the last byte (0x03).
-  if (*data_ == 0x03 && (prev_two_bytes_ & 0xffff) == 0) {
-    // Detected 0x000003, skip last byte.
+  if (bytes_left_ >= 1) {
+    // Load a new byte and advance pointers.
+    curr_byte_ = *data_;
     ++data_;
     --bytes_left_;
-    // Need another full three bytes before we can detect the sequence again.
-    prev_two_bytes_ = 0xffff;
-
-    if (bytes_left_ < 1)
-      return false;
+    num_remaining_bits_in_curr_byte_ = 8;
   }
 
-  // Load a new byte and advance pointers.
-  curr_byte_ = *data_++ & 0xff;
-  --bytes_left_;
-  num_remaining_bits_in_curr_byte_ = 8;
-
-  prev_two_bytes_ = (prev_two_bytes_ << 8) | curr_byte_;
-
-  return true;
-}
-
-// Read |num_bits| (1 to 31 inclusive) from the stream and return them
-// in |out|, with first bit in the stream as MSB in |out| at position
-// (|num_bits| - 1).
-bool H264Parser::H264BitReader::ReadBits(int num_bits, int *out) {
-  int bits_left = num_bits;
-  *out = 0;
-  DCHECK(num_bits <= 31);
-
-  while (num_remaining_bits_in_curr_byte_ < bits_left) {
-    // Take all that's left in current byte, shift to make space for the rest.
-    *out = (curr_byte_ << (bits_left - num_remaining_bits_in_curr_byte_));
-    bits_left -= num_remaining_bits_in_curr_byte_;
-
-    if (!UpdateCurrByte())
-      return false;
+  // Check if this is the end of RBSP data.
+  if (bytes_left_ == 0) {
+    while (num_remaining_bits_in_curr_byte_ != 0 && curr_byte_ % 2 == 0) {

[acolwell GONE FROM CHROMIUM, 2012/06/28 17:31:25]

nit: Since we are dealing with bits I'd prefer !(curr_byte_ & 0x1) here and
curr_byte_ >>= 1 below.

+      --num_remaining_bits_in_curr_byte_;
+      curr_byte_ /= 2;
+    }
   }
-
-  *out |= (curr_byte_ >> (num_remaining_bits_in_curr_byte_ - bits_left));
-  *out &= ((1 << num_bits) - 1);
-  num_remaining_bits_in_curr_byte_ -= bits_left;
-
-  return true;
-}
-
-off_t H264Parser::H264BitReader::NumBitsLeft() {
-  return (num_remaining_bits_in_curr_byte_ + bytes_left_ * 8);
-}
-
-bool H264Parser::H264BitReader::HasMoreRBSPData() {
-  // Make sure we have more bits, if we are at 0 bits in current byte
-  // and updating current byte fails, we don't have more data anyway.
-  if (num_remaining_bits_in_curr_byte_ == 0 && !UpdateCurrByte())
-      return false;
-
-  // On last byte?
-  if (bytes_left_)
-    return true;
-
-  // Last byte, look for stop bit;
-  // We have more RBSP data if the last non-zero bit we find is not the
-  // first available bit.
-  return (curr_byte_ &
-          ((1 << (num_remaining_bits_in_curr_byte_ - 1)) - 1)) != 0;
 }
 
 #define READ_BITS_OR_RETURN(num_bits, out)                                    \
@@ -358,7 +297,9 @@ H264Parser::Result H264Parser::AdvanceToNextNALU(H264NALU *nalu) {
   nalu->data = stream_ + off_to_nalu_start;
 
   // Initialize bit reader at the start of found NALU.
-  if (!br_.Initialize(nalu->data, nalu->size))
+  br_.Initialize(nalu->data, nalu->size);
+
+  if (!br_.HasMoreData())
     return kEOStream;
 
   DVLOG(4) << "Looking for NALU, Stream bytes left: " << bytes_left_
@@ -812,7 +753,7 @@ H264Parser::Result H264Parser::ParsePPS(int* pps_id) {
   READ_BOOL_OR_RETURN(&pps->constrained_intra_pred_flag);
   READ_BOOL_OR_RETURN(&pps->redundant_pic_cnt_present_flag);
 
-  if (br_.HasMoreRBSPData()) {
+  if (br_.HasMoreData()) {
     READ_BOOL_OR_RETURN(&pps->transform_8x8_mode_flag);
     READ_BOOL_OR_RETURN(&pps->pic_scaling_matrix_present_flag);