public bool NextNalUnit()
{
// FIXME: 00 00 01 xx -OF- 00 00 00 01 xx voor volgende NAL unit (extra (0) hoort dus bij volgende NAL unit)
// 00000000 00000000 00000001 0xxxxxxx
long startPosition = _dataReader.Position;
uint startCode = _dataReader.NextStartCode(25, 0x0000002, 7);
if (_dataReader.Position > (startPosition + _maxNalUnitDistance))
{
Result.Invalidate();
return(false);
}
if (startCode != 0)
{
return(true);
}
if (_dataReader.Position == _dataReader.Length)
{
return(true);
}
return(false); // This is unlikely to occur, but should return 'false'
}
private IStreamParser FindNalUnit(bool firstHeader)
{
bool detectByteStreamFormat = firstHeader || (_streamParser == _byteStreamParser);
bool detectNalUnitStreamFormat = firstHeader || (_streamParser == _nalUnitStreamParser);
while (_dataReader.State == DataReaderState.Ready)
{
// Note: This assumes that a valid NAL unit is less than 1MB in size.
uint startCode = _dataReader.NextStartCode(9, 0, 23);
long bytesRemaining = (_dataReader.Length - _dataReader.Position);
if (bytesRemaining < 4)
{
_dataReader.Position = _dataReader.Length;
break;
}
// Check for 'byte stream' format with '00 00 01' start code prefix
if (detectByteStreamFormat)
{
if (((startCode & ~0xff) == 0x00000100) && NalUnitStartByteByteStream[startCode & 0xff])
{
return(_byteStreamParser);
}
}
// Check for 'NAL unit stream' format: "00 LL xx", where 'LL' is the length prefix and 'xx' is the NAL unit byte
if (detectNalUnitStreamFormat)
{
if (_nalUnitStreamParser.IsShortLengthPrefixedNalUnit(startCode >> 8, bytesRemaining))
{
// Note: The data should not contain illegal sequences of '00 00 0x xx',
// other than start code prefix emulation prevention sequences.
return(_nalUnitStreamParser);
}
}
// Advance to next position, i.e. the NAL unit byte
_dataReader.Position++;
// Check for 'byte stream' format with '00 00 00 01' start code prefix
var nalUnitByte = (byte)(_dataReader.ShowBits(32) & 0xff);
if (detectByteStreamFormat)
{
if ((startCode == 0x00000001) && NalUnitStartByteSequenceParameterSet[nalUnitByte])
{
_dataReader.Position--;
return(_byteStreamParser);
}
}
// Check for 'NAL unit stream' format: "00 LL LL LL xx", where 'LLLLLL' is the length prefix and 'xx' is the NAL unit byte
if (detectNalUnitStreamFormat)
{
ulong nextFiveBytes = ((ulong)startCode << 8) | nalUnitByte;
if (_nalUnitStreamParser.IsLongLengthPrefixedNalUnit(nextFiveBytes, bytesRemaining))
{
// TODO: The data should not contain illegal sequences of '00 00 0x xx',
// other than start code prefix emulation prevention sequences.
_dataReader.Position--;
return(_nalUnitStreamParser);
}
}
}
// No more NAL units!
return(null);
}
public uint NextStartCode()
{
// Start code format is 23 bits (0), 1 bit (1), 8 bits (id)
return(_dataReader.NextStartCode(24, 0x000001, 8));
}