QR decoding with zbar probelm

[Ahmad Slo]

Hello,
I'm encoding a byte array into qr code using libqrencode and than try to decode it using zbar library. the programming language is c++.
The problem occurs when the values are >=128. for example when I decode the qr code which contains the following values:

unsigned char data[17]={111, 127, 128, 224, 255, 178, 201,200, 192, 191,22, 17,20, 34, 65 ,23, 76};

symbol->get_data_length() return 25 instead of 17 and when I tried to print the values using this small piece of code:

string input_data = symbol->get_data();
for(int k=0; k< 25; k++)
cout<< (int)((unsigned char)input_data[k])<<", ";

I got the following result:
111, 127, 194, 128, 195, 160, 195, 191, 194, 178, 195, 137, 195, 136, 195, 128, 194, 191, 22, 17, 20, 34, 65, 23, 76,

So as we can notice the values < 128 didn't effected but I got two bytes for every value >=128. Also I printed the values without casting to unsigned char:

for(int k=0; k< 25; k++)
cout<< (int)input_data[k]<<", ";

and the result is:
111, 127, -62, -128, -61, -96, -61, -65, -62, -78, -61, -119, -61, -120, -61, -128, -62, -65, 22, 17, 20, 34, 65, 23, 76

I solve this problem by the following code:

void process_zbar_output(const string & input_data, vector<unsigned char=""> & output_data)
{
for (int i = 0; i < input_data.length(); i++)
{
int temp = (int) input_data[i];
// if the original value is >=128 we need to process it to get the original value
if (temp < 0)
{
// if the number is 62 than the original is between 128 and 191
// if the number is 61 than the original is between 192 and 255
if (temp == -62)
output_data.push_back(256 + ((int) input_data[i + 1]));
else
output_data.push_back(256 + ((int) input_data[i + 1] + 64));
i++;
}
else
{
output_data.push_back( input_data[i]);
}
}
}

Can anybody help me with this problem and explain why I got these extra bytes?

notice: the decoded values are (194, 128 when casting to uchar) or (-62, -128 without casting to uchar) instead of 128. So I used the values (-62, -128) in my function "process_zbar_output" to get the original value. Moreover I can get the original values in range [128..191] from the second component (194, 128) and it is true for all values in this range. But that isn't true for values in range [192..255].

[Karskanov Ivan]

Hello.
libZbar not support reading raw data. It return decoded data as text in UTF-8.
If code contain binary data, library suppose than it is text in ISO 8859-1 code page and convert it to utf-8.
Same question discussed many times in this forum, but project seems not supported.