I want to convert a .wav file to binary,modulate it,transmit,demodulate and convert the binary back to .wav file.But I am not able to write binary data back to wav file.

wavdata = audioread('roja.wav');
wavbinary = dec2bin( typecast( single(wavdata(:)), 'uint8'), 8 ) - '0';
orig_size = size(wavdata);
wavb1=uint8(wavbinary);
w1=reshape(wavb1,15486976,1);
xmod=qammod(w1,16,0,'gray');
y1=awgn(xmod,10);
rdmod=qamdemod(y1,16,0,'gray');
% rdmod1=reshape(rdmod,1935872,8);
rdmod2=uint8(rdmod);
data = uint8(bin2dec( char( reshape( rdmod2, 8,[]).'+'0')));
audiowrite(data, 'rec_roja.wav',8000)

Error using bin2dec (line 55)
Binary string may consist only of characters 0 and 1

Error in wavb (line 14)
data = uint8(bin2dec( char( reshape( rdmod2, 8,[]).'+'0')));
 also waveread is not working in r2016

[KALYAN ACHARJYA]

Can you share roja.wav this file, so that we can try on your code?

[KALYAN ACHARJYA]

Delete your comment from answer section, please note this is comment section, you can use google drive and share

[NEEMA RAJ]

This is the zip file which contains .wav file

[NEEMA RAJ]

https://drive.google.com/open?id=1X9mdV3hQ8VJyI0u3iAKD-nEIW1yKEMux

The link in google drive also provided.

[KALYAN ACHARJYA]

OK

[NEEMA RAJ]

Could you decode the error?Is there any problem with audiowrite()?

Answer 1

[Walter Roberson]

Which release are you using? R2016a was the last release that accepted by initial phase (0) and symbol order (gray) for qammod, with R2016b being the last release that permitted initial phase.

In current releases, the default output for qamdemod is integer, and the integers can be anywhere from 0 to M-1 where M is the order you passed (which is 16 in your case). Current releases have an option 'outputtype', 'bit'

But when you qammod(), in current releases the default input is integer as well, and you would need 'inputtype', 'bit' to specify bits.

Which is to say, you are currently telling qammod that your inputs are integers in the range 0 to 15, but it just happens that none of them are anything other than 0 or 1. You then add white noise and decode. But the white noise might happen to knock some of the symbols into a different constellation, so you when you qamdemod you can get back integers other than what you put in.

If you were using modern MATLAB, you would

xmod=qammod(w1, 16, 'gray', 'inputtype', 'bit');

and

rdmod=qamdemod(y1, 16, 'gray', 'outputtype', 'bit');

and the problem with bin2dec would no longer occur.

[NEEMA RAJ]

I am using R2016a release.

[Walter Roberson]

In R2016a you should be able to use the calls I show.

[NEEMA RAJ]

clc;
clear all;
close all;
wavdata = audioread('roja.wav');
wavbinary = dec2bin( typecast( single(wavdata(:)), 'uint8'), 8 ) - '0';
orig_size = size(wavdata);
wavb1=uint8(wavbinary);
w1=reshape(wavb1,15486976,1);
% xmod=qammod(w1,16,0,'gray');
xmod=qammod(w1, 16, 'gray', 'inputtype', 'bit');
y1=awgn(xmod,10);
% rdmod=qamdemod(y1,16,0,'gray');
rdmod=qamdemod(y1, 16, 'gray', 'outputtype', 'bit');
rdmod1=reshape(rdmod,1935872,8);
data = uint8(bin2dec( char( reshape( rdmod1, 8,[]).'+'0')));
audiowrite(data, 'rec_roja.wav',8000)

Now the error shows

Error using audiowrite
The value of 'filename' is invalid. Expected input to be one of these types:

char

Instead its type was uint8.

Error in audiowrite>parseInputs (line 226)
parse(p,filename, y, Fs, pvpairs{:});

Error in audiowrite (line 103)
props = parseInputs(filename, y, Fs, varargin);

Error in wavb (line 16)
audiowrite(data, 'rec_roja.wav',8000)

[Walter Roberson]

filename goes before the data for audiowrite()

[NEEMA RAJ]

Error using audiowrite>validateFilename (line 323)
Cannot create file rec_roja1.wav. Permission Denied.

Error in audiowrite (line 105)
[props.filename, fileExisted] = validateFilename( props.filename );

Error in wavb (line 17)
audiowrite('rec_roja1.wav',data,8000)

The above error shows

[NEEMA RAJ]

The audiowrite() is still showing error.

[Walter Roberson]

   appdata = getenv('APPDATA');
   if isempty(appdata)
     error('No APPDATA?? Either not a PC or badly configured!');
   end
   mapp = fullfile(appdata, 'MATLAB');
   if ~isdir(mapp)
     try
       mkdir(mapp);
     catch ME
       error('Failed to create directory "%s"', mapp);
     end
   end
   mq = fullfile(mapp, 'Q420697');
   if ~isdir(mq)
     try
       mkdir(mq);
     catch ME
       error('Failed to create directory "%s"', mq);
     end
   end

   outfile = fullfile(mq, 'rec_roja1.wav');

   audiowrite(outfile, data, 8000);

   fprintf('Your file was saved to: "%s"\n', outfile);

[NEEMA RAJ]

Thank you.It works!!!