%%% Real-Time Speech Pitch Shifting on an FPGA
%%% Estephan, Sawyer, Wanninger
%%% M-File by Habib Estephan (2006)
%%% Villanova University
%%% Department of Electrical and Computer Engineering


clear; clc

Nin=wavread('freddie_mono.wav'); %input wave
Nin=Nin';            				%Input's transpose to make it a 1xM array
SampleFreq=44100;    				%Sampling Frequency of the input
windowsize=1800;     				%Specifies the Size of the block 
estimperiod=(5e-3)*SampleFreq; 	%Calculates the number of samples in 5 ms of signal 
                                %which is the typical period of human's
                                %speech fundemental frequency
maxnumperiod=floor(windowsize/estimperiod)  %Calculates the total periods in one block
numperiod=2                     %Specifies the number of periods taken out of each block

if numperiod>maxnumperiod       %this if statement gurantees that the number of truncated periods is less
                                %than the total number of periods in that
                                %specific block
    nunmperiod=maxnumperiod-1;
end
x=round(length(Nin)/windowsize);
Nout=floor(windowsize*x-numperiod*estimperiod);

Output=zeros(1,100);            %Defines the output vector that will contain the truncated blocks
                                %from the input vector
for n=1:round((length(Nin)/windowsize))
    start=windowsize*n+(1-windowsize)   %points to the beginning of the next block from the input
    last=floor(windowsize*n-numperiod*estimperiod)  %points to the end of the next block from the input
    section=Nin(start:last);    %Section will contain the current block through each iteration
    l=length(section);          %Length of Section
    st=n*l+1-l;                 %points to the location of insertion of the truncated block into the output vector
    lst=n*l;                    %points to the final location of the truncated block into the output vector
    Output(st:lst)=section;     %Output vector
end
ratio=length(Output)/length(Nin);
[t,d]=rat(ratio);               %returns the the ratio as a fraction, where the Numerator is stored in t
                                %and the denominator is stored in d.


Out1=resample(Output,d,t);      %in order to play the outputed signal at the same rate we 
  %have resample it at 
                                %a rate that d/t the current sampling rate
                                %in order to rescale the output vector and
                                %make it the same length as the
                                %input
Sound(Out1,SampleFreq)