How do I decode this binary string in python?

Question

So, I have this string 01010011101100000110010101101100011011000110111101110100011010000110010101110010011001010110100001101111011101110111100101101111011101010110010001101111011010010110111001100111011010010110110101100110011010010110111001100101011000010111001001100101011110010110111101110101011001100110100101101110011001010101000000000000

and I want to decode it using python, I'm getting this error UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb0 in position 280: invalid start byte

According to this webiste: https://www.binaryhexconverter.com/binary-to-ascii-text-converter

The output should be S�ellotherehowyoudoingimfineareyoufineP

Here's my code:

def decodeAscii(bin_string):
    binary_int = int(bin_string, 2);
  
    byte_number = binary_int.bit_length() + 7 // 8
    binary_array = binary_int.to_bytes(byte_number, "big")
    ascii_text = binary_array.decode()
    
    print(ascii_text)

How do I fix it?

The � in the output seems to indicate a weird character outside the normal ascii range. Why is that there? — khelwood
– khelwood, Commented Sep 23, 2021 at 7:47
@khelwood I'm trying to transfer data over the audio and this binary string was received by the receiver, where there is no error-correcting techniques were implemented. And that's the reason for it. — iwrestledthebeartwice
– iwrestledthebeartwice, Commented Sep 23, 2021 at 7:53

Mike Scotty · Accepted Answer · 2021-09-23 07:53:04Z

Your bytes simply cannot be decoded as utf-8, just as the error message tells you.

utf-8 is the default encoding parameter of decode - and the best way to put in the correct encoding value is to know the encoding - otherwise you'll have to guess.

And guessing is probably what the website does, too, by trying the most common encodings, until one does not throw an exception:

def decodeAscii(bin_string):
    binary_int = int(bin_string, 2);
    byte_number = binary_int.bit_length() + 7 // 8
    binary_array = binary_int.to_bytes(byte_number, "big")
    ascii_text = "Bin string cannot be decoded"
    for enc in ['utf-8', 'ascii', 'ansi']:
        try:
            ascii_text = binary_array.decode(encoding=enc)
            break
        except:
            pass
    print(ascii_text)

s = "01010011101100000110010101101100011011000110111101110100011010000110010101110010011001010110100001101111011101110111100101101111011101010110010001101111011010010110111001100111011010010110110101100110011010010110111001100101011000010111001001100101011110010110111101110101011001100110100101101110011001010101000000000000"
decodeAscii(s)

Output:

S°ellotherehowyoudoingimfineareyoufineP

But there's no guarantee that you find the "correct" encoding by guessing.

Yu Cheng · Accepted Answer · 2021-09-23 07:56:24Z

1

Your binary string is just not a valid ascii or utf-8 string. You can tell decode to ignore invalid sequences by saying

ascii_text = binary_array.decode(errors='ignore')

answered Sep 23, 2021 at 7:56

Yu Cheng

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1 Comment

Mike Scotty Over a year ago

Just keep in mind that this will more likely lead to a loss of actual data, compared to the try..except approach. E.g. print("Hello Wörld".encode("ansi").decode(errors='ignore')) will throw away the ö, while the try...except approach might eventually guess the correct encoding.

Sabil · Accepted Answer · 2021-09-23 08:12:02Z

1

It could be solved in one line:

Try this:

def bin_to_text(bin_str):
    bin_to_str = "".join([chr(int(bin_str[i:i+8],2)) for i in range(0,len(bin_str),8)])

    return bin_to_str

bin_str = '01010011101100000110010101101100011011000110111101110100011010000110010101110010011001010110100001101111011101110111100101101111011101010110010001101111011010010110111001100111011010010110110101100110011010010110111001100101011000010111001001100101011110010110111101110101011001100110100101101110011001010101000000000000'
bin_to_str = bin_to_text(bin_str)
print(bin_to_str)

Output:

S°ellotherehowyoudoingimfineareyoufineP

answered Sep 23, 2021 at 8:12

Sabil

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