diff options
Diffstat (limited to 'content/common/gpu/media/h264_parser.cc')
-rw-r--r-- | content/common/gpu/media/h264_parser.cc | 103 |
1 files changed, 4 insertions, 99 deletions
diff --git a/content/common/gpu/media/h264_parser.cc b/content/common/gpu/media/h264_parser.cc index ace3dab..1452238 100644 --- a/content/common/gpu/media/h264_parser.cc +++ b/content/common/gpu/media/h264_parser.cc @@ -50,103 +50,6 @@ 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() {} - -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; - - // 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. - ++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; - } - - // 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; - } - - *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) \ do { \ int _out; \ @@ -358,7 +261,9 @@ 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 +717,7 @@ 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); |