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Sound file [[Image:Example_ECE301Fall2008mboutin.jpg]]
  
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== MATLAB code ==
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<pre>
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% Ben Laskowski (blaskows@purdue.edu)
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% September 5, 2008
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% ECE301 Section 2 HW1
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%
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% This file is supposed to reverse and slow a wav file for extraction of
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% alleged subliminal messages.
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% Begin by clearing the output console and all memory.
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clear;
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clc;
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%Open the wave file and get its length, sample size, and sampling rate
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[data,fs,nbits]=wavread('jpforward.wav');
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%Play the file once normally
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disp('Playing the unaltered file...')
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wavplay(data,fs);
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%Reverse the file, play it, and write it out
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Length=size(data);
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MaxCount=Length(1);
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reversedata=zeros(MaxCount,1);
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for counter=MaxCount:-1:1
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    reversedata(MaxCount-counter+1,1)=data(counter);
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end
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disp('Playing reverse at normal speed...');
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wavplay(reversedata,fs);
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%To slow the original data, we can just write out the reversed data with
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% a fraction of the correct sampling rate.
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disp('Playing reverse at 67% speed...');
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wavwrite(reversedata,fs/1.5,nbits,'jpreverseslow.wav');
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wavplay(reversedata,fs/1.5);
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</pre>

Latest revision as of 11:40, 2 September 2008

Sound file Example ECE301Fall2008mboutin.jpg

MATLAB code

% Ben Laskowski (blaskows@purdue.edu)
% September 5, 2008
% ECE301 Section 2 HW1
%
% This file is supposed to reverse and slow a wav file for extraction of
% alleged subliminal messages.

% Begin by clearing the output console and all memory.
clear;
clc;

%Open the wave file and get its length, sample size, and sampling rate
[data,fs,nbits]=wavread('jpforward.wav');

%Play the file once normally
disp('Playing the unaltered file...')
wavplay(data,fs);

%Reverse the file, play it, and write it out
Length=size(data);
MaxCount=Length(1);
reversedata=zeros(MaxCount,1);
for counter=MaxCount:-1:1
    reversedata(MaxCount-counter+1,1)=data(counter);
end
disp('Playing reverse at normal speed...');
wavplay(reversedata,fs);


%To slow the original data, we can just write out the reversed data with
% a fraction of the correct sampling rate.
disp('Playing reverse at 67% speed...');
wavwrite(reversedata,fs/1.5,nbits,'jpreverseslow.wav');
wavplay(reversedata,fs/1.5);

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