I have audio, how to convert to ASCII code??

I have audio, i use audioread in program. how to convert audio to ASCII code??

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/29922-why-your-question-is-not-urgent-or-an-emergency

[Jan]

It depends on how the output should look like. ASCII code could mean a variety of formats. It could be a HEX string, or a comma separated list of the decimal values, or a base64 encoded sequence of the binary values. Please explain any details.

[heri purwantoro]

I use audioread code. there are 2 columns and many rows with values -1 to 1. from here how to change the value to ascii code??

[Jan]

@heri: Did you read my comment? If so, why do you ignore it?

If you have some values as e.g.

[-0.99, -0.87777765; ...
 -0.98, -0.8775; ...
 -0.3,  0.4];

What would you want as output? What does "ascii code" mean?

Maybe you mean the string:

 -0.99, -0.87777765; ...
 -0.98, -0.8775; ...
 -0.3,  0.4;

or

 -0.99 -0.8778
 -0.98 -0.8775
 -0.3 0.4

or

'[ -0.99, -0.87777765; -0.98, -0.8775; -0.3,  0.4]';

or a hexadecimal output, or a base64 encoded stream of characters or ...

We cannot guess, what you want. So please explain it.

[Guillaume]

To add to Jan's comment. ASCII Code is simply integer values from 0 to 127. So any conversion that mapped your values to integer values between 0 and 127 could be an answer to your question.

Until you tell us what these ASCII codes are supposed to represent we can't answer your question. We could map your -1 value to ascii code 0, we could map it to ascii code 127, we could map it to ascii sequence 45 49. How do we know what you want?

[heri purwantoro]

when i use audioread and i got

 -0.729 -0.367
 -0.017 0.253
 -0.016 0.273

from that value i want to convert to binary, and mathcing the ascii code. but i don't know how to convert the value to binary

[Guillaume]

Maybe you should explain what it is you want to achieve ultimately because you haven't made anything clearer. If anything, now we also do not know what mapping you want to convert to binary.

You could convert to binary using IEEE754 double precision, or using IEEE754 single precision or many other encoding schemes which would lead to completely different binary values of various lengths.

Then we still don't know how you'd convert these binary values to ASCII codes, which I'll remind you can only be integer values between 0 and 127.

[heri purwantoro]

Guillaume, my purpose convert audio to ascii, i want to encryption audio use cryptography algorithm.

why integer value between 0 until 127?

[Guillaume]

why integer value between 0 until 127?

Because that's the definition of ASCII. It's a 7-bit encoding so the values are from 0 to 2^7-1 == 127.

my purpose convert audio to ascii us[ing] cryptography algorithm

Yes, but what algorithm? Until you tell us the finer details of your algorithm we have no idea how to convert. As I said, there are many ways to convert some sequence of numbers into another sequence of numbers all producing different results.

[Jan]

@heri: If all you want is to encrypt the file, use fileread or fread(fileID, Inf, 'uint8'). You do not have to convert the signal, if you can encrypt the bytes directly.

Your explanations did not help yet to find out, what you want to achieve exactly.

Answer 1

[Walter Roberson]

reshape( num2hex(TheSignalArray(:)) .', 1, [])

[heri purwantoro]

it`s didn`t work

[Guillaume]

it didn't work

is a completely useless statement. It didn't work because:

• your computer wasn't turned on,
• you were struck by a bolt of lightning,
• it gave an error because you gave it the wrong input,
• it produced a different result to what you expected but you haven't told us what you expected,
• you haven't understood the answer?

How are we supposed to know if you don't tell us?

[Walter Roberson]

 char( reshape(typecast(TheSignalArray, 'uint8'), 1, []) )

[Walter Roberson]

Note that there are two ways you can do "audio encryption":

1) Read the audio file, and calculate an encrypted version of the signal. If the sampling frequency is not fixed, then you will need to either include it "in the clear" or you will need to include it in the information being encrypted. When you use this approach, all extra information such as track names and artist and copyright will be discarded and not transferred. It would be possible for the decrypting side to play the sound immediately after decrypting.

2) Read the audio file as a series of bytes or characters, and calculate an encrypted version of that. The decrypting side would typically need to write the decrypted information into a file and then read the file in order to be able to play the sound after decrypting. All extra information such as track names and artist and copyright will be included, whatever was in the original file.

[Walter Roberson]

Also, if you are planning to encrypt an audio signal, you should seriously consider using the 'native' option when you read the signal,

[data, fs] = audioread('Concerto For Jar-Jar.mp3', 'native');

This would often return integer data instead of floating point that you would get without 'native'