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SNR

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SNR

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15 Feb 2014 (Updated )

This MATLAB exercise computes and plots the SNR of a quantized speech file.

Callbacks_snr_GUI25(f,C,start_path)
function Callbacks_snr_GUI25(f,C,start_path)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
x=C{1,1};
y=C{1,2};
a=C{1,3};
b=C{1,4};
u=C{1,5};
v=C{1,6};
m=C{1,7};
n=C{1,8};
lengthbutton=C{1,9};
widthbutton=C{1,10};
enterType=C{1,11};
enterString=C{1,12};
enterLabel=C{1,13};
noPanels=C{1,14};
noGraphicPanels=C{1,15};
noButtons=C{1,16};
labelDist=C{1,17};%distance that the label is below the button
noTitles=C{1,18};
buttonTextSize=C{1,19};
labelTextSize=C{1,20};
textboxFont=C{1,21};
textboxString=C{1,22};
textboxWeight=C{1,23};
textboxAngle=C{1,24};
labelHeight=C{1,25};
fileName=C{1,26};
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%SET UP PATH DELIMITER
switch(computer)													% Get gs command.
    case 'MACI64',		char= '/';
    case 'GLNX86',  char='/';
    case 'PCWIN',	char= '\';
    case 'PCWIN64', char='\';
    case 'GLNXA64', char='/';
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%PANELS
for j=0:noPanels-1
uipanel('Parent',f,...
'Units','Normalized',...
'Position',[x(1+4*j) y(1+4*j) x(2+4*j)-x(1+4*j) y(3+4*j)-y(2+4*j)]);
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%GRAPHIC PANELS
for i=0:noGraphicPanels-1
switch (i+1)
case 1
graphicPanel1 = axes('parent',f,...
'Units','Normalized',...
'Position',[a(1+4*i) b(1+4*i) a(2+4*i)-a(1+4*i) b(3+4*i)-b(2+4*i)],...
'GridLineStyle','--');
end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%TITLE BOXES
for k=0:noTitles-1
switch (k+1)
case 1
titleBox1 = uicontrol('parent',f,...
'Units','Normalized',...
'Position',[u(1+4*k) v(1+4*k) u(2+4*k)-u(1+4*k) v(3+4*k)-v(2+4*k)],...
'Style','text',...
'FontSize',textboxFont{k+1},...
'String',textboxString(k+1),...
'FontWeight',textboxWeight{k+1},...
'FontAngle',textboxAngle{k+1});
end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%BUTTONS
for i=0:(noButtons-1)
enterColor='w';
if strcmp(enterType{i+1},'pushbutton')==1 ||strcmp(enterType{i+1},'text')==1
enterColor='default';
end
if (strcmp(enterLabel{1,(i+1)},'')==0 &&...
        strcmp(enterLabel{1,(i+1)},'...')==0) %i.e. there is a label
%creating a label for some buttons
uicontrol('Parent',f,...
'Units','Normalized',...
'Position',[m(1+2*i) n(1+2*i)-labelDist-labelHeight(i+1) ...
(m(2+2*i)-m(1+2*i)) labelHeight(i+1)],...
'Style','text',...
'String',enterLabel{i+1},...
'FontSize', labelTextSize(i+1),...
'HorizontalAlignment','center');
end
switch (i+1)
case 1
button1=uicontrol('Parent',f,...
'Units','Normalized',...
'Position',[m(1+2*i) n(1+2*i) (m(2+2*i)-m(1+2*i)) (n(2+2*i)-n(1+2*i))],...
'Style',enterType{i+1},...
'String',enterString{i+1},...
'FontSize', buttonTextSize(1+i),...
'BackgroundColor',enterColor,...
'HorizontalAlignment','center',...
'Callback',@button1Callback);
case 2
button2=uicontrol('Parent',f,...
'Units','Normalized',...
'Position',[m(1+2*i) n(1+2*i) (m(2+2*i)-m(1+2*i)) (n(2+2*i)-n(1+2*i))],...
'Style',enterType{i+1},...
'String',enterString{i+1},...
'FontSize', buttonTextSize(1+i),...
'BackgroundColor',enterColor,...
'HorizontalAlignment','center',...
'Callback',@button2Callback);
case 3
button3=uicontrol('Parent',f,...
'Units','Normalized',...
'Position',[m(1+2*i) n(1+2*i) (m(2+2*i)-m(1+2*i)) (n(2+2*i)-n(1+2*i))],...
'Style',enterType{i+1},...
'String',enterString{i+1},...
'FontSize', buttonTextSize(1+i),...
'BackgroundColor',enterColor,...
'HorizontalAlignment','center',...
'Callback',@button3Callback);
case 4
button4=uicontrol('Parent',f,...
'Units','Normalized',...
'Position',[m(1+2*i) n(1+2*i) (m(2+2*i)-m(1+2*i)) (n(2+2*i)-n(1+2*i))],...
'Style',enterType{i+1},...
'String',enterString{i+1},...
'FontSize', buttonTextSize(1+i),...
'BackgroundColor',enterColor,...
'HorizontalAlignment','center',...
'Callback',@button4Callback);
case 5
button5=uicontrol('Parent',f,...
'Units','Normalized',...
'Position',[m(1+2*i) n(1+2*i) (m(2+2*i)-m(1+2*i)) (n(2+2*i)-n(1+2*i))],...
'Style',enterType{i+1},...
'String',enterString{i+1},...
'FontSize', buttonTextSize(1+i),...
'BackgroundColor',enterColor,...
'HorizontalAlignment','center',...
'Callback',@button5Callback);
case 6
button6=uicontrol('Parent',f,...
'Units','Normalized',...
'Position',[m(1+2*i) n(1+2*i) (m(2+2*i)-m(1+2*i)) (n(2+2*i)-n(1+2*i))],...
'Style',enterType{i+1},...
'String',enterString{i+1},...
'FontSize', buttonTextSize(1+i),...
'BackgroundColor',enterColor,...
'HorizontalAlignment','center',...
'Callback',@button6Callback);
case 7
button7=uicontrol('Parent',f,...
'Units','Normalized',...
'Position',[m(1+2*i) n(1+2*i) (m(2+2*i)-m(1+2*i)) (n(2+2*i)-n(1+2*i))],...
'Style',enterType{i+1},...
'String',enterString{i+1},...
'FontSize', buttonTextSize(1+i),...
'BackgroundColor',enterColor,...
'HorizontalAlignment','center',...
'Callback',@button7Callback);
case 8
button8=uicontrol('Parent',f,...
'Units','Normalized',...
'Position',[m(1+2*i) n(1+2*i) (m(2+2*i)-m(1+2*i)) (n(2+2*i)-n(1+2*i))],...
'Style',enterType{i+1},...
'String',enterString{i+1},...
'FontSize', buttonTextSize(1+i),...
'BackgroundColor',enterColor,...
'HorizontalAlignment','center',...
'Callback',@button8Callback);
end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%USER CODE FOR THE VARIABLES AND CALLBACKS
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Initialize Variables
    curr_file=1;
    fs=8000;
    directory_name='abcd';
    wav_file_names='abce';
    fin_path='filename';
    fname='output';
    nsamp=1;
    ss=1;
    es=106980;
    xin=[];
    mu=100;
    iuse=1;

% Name the GUI
    set(f,'Name','snr_range');

% CALLBACKS
% Callback for button1 -- Get Speech Files Directory
 function button1Callback(h,eventdata)
     directory_name=uigetdir(start_path,'dialog_title');
%      if isempty(getpref('SpeechApps'))
%          url = sprintf('%s%s%s',...
%              'http://www.mathworks.com/matlabcentral/fileexchange/',...
%              '42911-speech-and-audio-files-for-speech-processing-excercises',...
%              '?download=true');
%          [saveloc,~,~] = fileparts(pwd); %save to one level up from current folder
%          % Create a waitbar during download
%          h = waitbar(0.35,'This may take several minutes...',...
%              'Name','Downloading Speech Files...');
%          % Download the zipped file
%          [filestr,status] = urlwrite(url,[saveloc filesep 'speech_files.zip'],...
%              'Timeout',10);
%          if status
%              delete(h);
%              hh1= helpdlg('Downloaded. Select a location to UNZIP the speech files.');
%              uiwait(hh1);
%              unziploc = uigetdir(saveloc,'Select a location to unzip the speech files');
%              h2 = waitbar(0.2,'This may take a minute...',...
%                  'Name','Unzipping the Speech Files to Location Selected...');
%              unzip(filestr,unziploc);
%              delete(h2)
%              addpref('SpeechApps','path',unziploc);
%              hh2= helpdlg('Ready. Select the speech_files folder in the next window');
%              uiwait(hh2);
%          else
%              warndlg('No Internet Connection to MATLAB Central!');
%          end
%          
%      else
%      end
%      directory_name=uigetdir(getpref('SpeechApps','path'));
     A=strvcat(strcat((directory_name),[char,'*.wav']));
     struct_filenames=dir(A);
     wav_file_names={struct_filenames.name};
     set(button2,'String',wav_file_names);
     
% once the popupmenu/drop down menu is created, by default, the first
% selection from the popupmenu/drop down menu id not called
    indexOfDrpDwnMenu=1;
    
% by default first option from the popupmenu/dropdown menu will be loaded
    [curr_file,fs]=loadSelection(directory_name,wav_file_names,indexOfDrpDwnMenu);
 end

% Callback for button2 -- Choose speech file for play and plot
 function button2Callback(h,eventdata)
     indexOfDrpDwnMenu=get(button2,'val');
     [curr_file,fs]=loadSelection(directory_name,wav_file_names,indexOfDrpDwnMenu);
 end

%*************************************************************************
% function -- load selection from designated directory and file
%
function [curr_file,fs]=loadSelection(directory_name,wav_file_names,...
    indexOfDrpDwnMenu);
%
% read in speech/audio file
% fin_path is the complete path of the .wav file that is selected
    fin_path=strcat(directory_name,char,strvcat(wav_file_names(indexOfDrpDwnMenu)));
    
% clear speech/audio file
    clear curr_file;
    
% read in speech/audio signal into curr_file; sampling rate is fs 
    [curr_file,fs]=wavread(fin_path);
    xin=curr_file*32768;
    
% create title information with file, sampling rate, number of samples
    fname=wav_file_names(indexOfDrpDwnMenu);
    FS=num2str(fs);
    nsamp=num2str(length(curr_file));
    file_info_string=strcat('  file: ',fname,', fs: ',FS,' Hz, nsamp:',nsamp);
    fname=wav_file_names{indexOfDrpDwnMenu};
end

% Callback for button3 -- ss: starting sample in file
 function button3Callback(h,eventdata)
     ss=1;
     set(button3,'string',num2str(ss));
 end

% Callback for button4 -- es: ending sample in file
 function button4Callback(h,eventdata)
     es=length(xin);
     set(button4,'string',num2str(es));
 end

% Callback for button5 -- mu: value of mu-law compression
 function button5Callback(h,eventdata)
     mu=str2num(get(button5,'string'));
     if ~((mu >= 1 && mu <= 500))
        waitfor(errordlg('mu must be a positive integer between 1 and 500'))
        return;
     end
     mu=round(mu);
     set(button5,'string',num2str(mu));
 end

% Callback for button6 -- iuse: switch on plotting of theoretical snr
% curves; (1): plot snr curves; (2) don't plot snr curves
 function button6Callback(h,eventdata)
     iuse=get(button6,'val');
 end

% Callback for button7 -- run snr plot
 function button7Callback(h,eventdata)
     
% check editable buttons for changes
    button3Callback(h,eventdata);
    button4Callback(h,eventdata);
    button5Callback(h,eventdata);
    button6Callback(h,eventdata);
    
% setup snr plots and run
    setup_snr_range(xin,fs,ss,es,mu,iuse,fname);
 end

    function setup_snr_range(xin,fs,ss,es,mu,iuse,filein)
%
% plot snr of uniform and mu-law coders over range of signal levels and
% number of bits in the quantizer; neglecting overload situations
%
% Inputs:
%   xin: speech file
%   fs: speech sampling rate
%   ss: starting sample in file
%   es: ending sample in file
%   mu: value of mu for mu-law companding
%   iuse: plot theoretical snr curves; (1):YES, (2):NO
%   filein: input speech file

% scale input to [-1 1] range
    xinn=xin(ss:es)/max(max(xin),-min(xin));
    
% vary signal range and plot
    nbitr=[12 10  8 6];
    
% plot the original speech file in graphPanel3 (striplot file)
        reset(graphicPanel1);
        axes(graphicPanel1);
        cla;
                   
% compute the snr and plot it over the range of signal levels
        qplot_new3(xinn,nbitr,mu,iuse);
        
% finish up with the plots
        grid on; ylabel('SNR in dB');
        xlabel('X_{max}/\sigma_x');
        
% title GUI plot
    stitle=sprintf(' file: %s, ss/es: %d  %d, mu: %d',filein,ss,es,mu);
    string=sprintf('; nbits=12,10,8,6');
    stitle1=strcat('SNR for Uniform and Mu-Law Quantizers -- ',stitle,string);   
    set(titleBox1,'string',stitle1);
    set(titleBox1,'FontSize',15);
    end

% Callback for button8 -- close GUI
 function button8Callback(h,eventdata)
     fclose('all');
     close(gcf);
 end
end

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