    bool isJpegType(BasicIo& iIo, bool advance)
    {
        bool result = true;
        byte tmpBuf[2];
        iIo.read(tmpBuf, 2);
        if (iIo.error() || iIo.eof()) return false;

        if (0xff != tmpBuf[0] || JpegImage::soi_ != tmpBuf[1]) {
            result = false;
        }
        if (!advance || !result ) iIo.seek(-2, BasicIo::cur);
        return result;
    }
Unknown