what does 'b' denote in this code.please tell me I am cofused with it?

[y,Fs]=audioread('alarm456.wav');
file_read=resample(y,1,44100);
byte_size_of_sampled_signal=getByteSize(file_read);
file_open=fopen('file_read','r');
a=roundn(file_read,-3);
b=zeros(1,2*length(a));
where'a' is a sampled signal.

[Rena Berman]

(Answers dev) Restored deleted comments.

Answer 1

[Azzi Abdelmalek]

Just run this, you will understand

b=zeros(4,3)

or

a=[2 1 3]
n=length(a)
b=zeros(1,n)

[PRATIBHA WARKADE]

no sir I am not getting it sir...if I put a=zeros(4,3),I am getting the value of 'b' as zero..

[PRATIBHA WARKADE]

sir,this is my whole code please sir do help me to know about all the variable like 'b' and what does it denote in this code?

audio signal having 4.82MB as size and 44100hz as sampling frequency:

[y,Fs]=audioread('x.wav');
file_read=resample(y,1,44100);
byte_size_of_sampled_signal=getByteSize(file_read);
file_open=fopen('file_read','r');
a=round(file_read,-3);
b=zeros(1,2*length(a));
for sort_len=1:length(b)
   if(sort_len>length(a))

b(sort_len)=a(sort_len-length(a));
else
    b(sort_len)=a(sort_len);
   end
end
x=b;
to_sort=zeros(length(a),length(a));
for row_sort=1:length(a);
    to_sort(row_sort,:)=b(row_sort:length(a)+row_sort-1);
end
[lexi_sorted_data,ind]=sortrows(to_sort);
encoded_data=lexi_sorted_data(:,length(a));
primary_index=find(ind==2);
out_data=[encoded_data',primary_index];
file_bwt=fopen('bwt.cmp','w');
fwrite(file_bwt,out_data,'uint8');
fclose(file_bwt);
s=out_data;
        l=length(s);
        uniquevalue = unique(s);  % String s has all unique symbol sorted

          lenvalue = length(uniquevalue);

          f=zeros(1,lenvalue);

          for i=1:lenvalue
          f(i)=length(strfind(s,uniquevalue(i)));% Count the occurence of unique characters end

          p=zeros(1,lenvalue);

          for i=1:lenvalue %#ok<FXSET>
              p(i)=f(i)/l ; %  Probabilities for each unique character end
                 Entropy=0;

                   for  i=1:lenvalue %#ok<FXSET>
                    Entropy = Entropy + (-p(i)*log2(p(i)));  % Calculating the Entropy
                  end
          end

          end
  symbols =  unique(out_data) ;% Distinct data symbols appearing in sig
  dict = huffmandict(symbols,p); % Create the dictionary.
  hcode = huffmanenco(out_data,dict); % Encode the data.
  plot(hcode,'b');
  byte_Size_of_compressed_data=getByteSize(hcode);
  disp('compression ratio');
  CR=(byte_Size_of_compressed_data)/(byte_size_of_sampled_signal);
  dhsig = huffmandeco(hcode,dict); % Decode the code.
  symbols = (1:length(p)); % Distinct symbols that data source can produce
  [dict] = huffmandict(symbols,p); % Create dictionary.
  actualsig = randsrc(1,100,[symbols; p]); % Create data using p.
  comp = huffmanenco(actualsig,dict); % Encode the data.
  dsig = huffmandeco(comp,dict); % Decode the Huffman code.
  isequal(actualsig,dsig)% Check whether the decoding is correct.
  encoded_bwt_file=fopen('bwt.cmp','r');
  dec_bwt_read=fread(encoded_bwt_file,'uint8');
  fclose(encoded_bwt_file);
  disp('BWT DECODING Started')

encoded_data=dec_bwt_read(1:length(dec_bwt_read)-1);
primary_index=dec_bwt_read(length(dec_bwt_read));

sorted_data=sort(encoded_data);
vector_flag=ones(1,length(encoded_data))';
vector=zeros(1,length(encoded_data))';
%%%%%%%preparing vector table
for i=1:length(sorted_data)
    for j=1:length(sorted_data)
        if(encoded_data(j)==sorted_data(i) && vector_flag(j))
        %             clc;
        %             encoded_data(j);
        %             sorted_data(i);
        vector_flag(j);  %#ok<NOEFF>
        vector(i)=j;
        vector_flag(j)=0;
        break

          end
      end
   end

index=primary_index;
reconst_data=zeros(1,length(encoded_data));
%getting original data back
for i=1:length(encoded_data)
    reconst_data(i)=encoded_data(index);
    index=vector(index);
end

rec_file=fopen('orig_file.txt','w');
fwrite(rec_file,reconst_data,'uint8');
fclose(rec_file);
disp('BWT Decoding over..')
disp('file written back as orig_file.txt')

[Walter Roberson]

You wrote the code; why do you not know what your variables are for?

[PRATIBHA WARKADE]

sir, I m confused with 'b' denotes what?whether it is byte size or not?

[Muthu Annamalai]

It seems like they want to audio encode using (entropy encoding) data compression algorithms; pretty unique in that I haven't seen any such before doing some form of lossy transformation. FLAC comes to mind.

[Walter Roberson]

What did you intend for it to be when you wrote the code?

[PRATIBHA WARKADE]

actually sir I want to calculate the compression ratio of it.But I am not getting why we are keeping b=zeros(1,2*length(a)),whats the need of it?

[Walter Roberson]

When you wrote that line of code, what did you intend the line to mean?

To answer your earlier question: no, "b" has nothing to do with byte size.

[PRATIBHA WARKADE]

thank you sir for your valuable suggestion