Audio equalizer

Audio Equalizer in Matlab

NUST School of Electrical Engineering and Computer Science (SEECS)

http://www.seecs.nust.edu.pk/

http://www.seecs.nust.edu.pk/

05/01/2023Audio Equalizer.............................................Hasham_Khan

Task

Task is to design a 10-band software audio equalizer.


Step By Step Approach

Open Matlab Using “ guide ” function create a new GUI


For 10 bands Audio Equalizer we need 10 sliders… so select 10 sliders


After the completion of previous step your design will be like this ;


Define the values for each slider handles• global stop C Fs;• stop=1;• Fs=44100;• C=zeros(1,10);

Slider 1 values are as follow;• set(handles.slider1,'min',-20);• set(handles.slider1,'max',20);• set(handles.slider1,'value',0);• set(handles. slider1,'SliderStep',[0.025,0.05]);• set(handles. slider1,'string',num2str(0));

Repeat the above steps for all 10 Sliders


Double click on each slider and click “ callback” and “ CreateFtn ”…By clicking both you will see both functions in your m file


To get the different values of slider add “get” function• % Executes on slider movement.• function slider1_Callback(hObject, eventdata, handles)• global C;• C(1)=get(hObject,'value');• set(handles.slider1_val,'string',num2str(C(1)));• % --- Executes during object creation, after setting all properties.• function slider1_CreateFcn(hObject, eventdata, handles)• if isequal(get(hObject,'BackgroundColor'),

get(0,'defaultUicontrolBackgroundColor'))• set(hObject,'BackgroundColor',[.9 .9 .9]);• end

Repeat the above steps for all 10 sliders


To add “Load”, “ Reset ”, “ Play ” ,“ Stop ’’ buttons use the Push button in the GUI

Double click on Push button and change the string and tag as load , reset , play and stop.


Now after adding the button your design will be like this ;


Double click on each button and select callback function For Reset button :• set(handles.slider1_val,'string',num2str(0));• set(handles.slider1_var,'value',0); Repeat the above step for all 10 sliders

For Load button :• % -Executes on button press in load.• function load_Callback(hObject, eventdata, handles)• global file_name;• file_name=uigetfile('*wav','hasham .wav');


For Stop and Play Button :• % --- Executes on button press in play.• function play_Callback(hObject,

eventdata, handles) • global stop file_name C;• stop=1;• equalizer_play();• function equalizer_play()• global stop file_name C;• [x,Fs]=wavread(file_name);• [a,b]=coef();• l_bucata=2*Fs;• Nb=round(length(x)/l_bucata);• y=0;• for i=1:floor(Nb)• bucata=x((i-1)*l_bucata+1:i*l_bucata);• for k=1:5• y=y+filter(10^(C(k)/

20)*b{k},a{k},bucata);• if(stop==0)• break;

• end • end• wavplay(y,Fs,'async');• y=0;• if(stop==0)• break;• end • end• % --- Executes on button press in stop.• function stop_Callback(hObject, eventdata,

handles)• global stop;• stop=0;


Add Edit Text to each slider and double click the edit text icon and select “callback” and “CreateFtn” for each slider


After adding the edit text to each slider your design will be like this ;


To have the value of each slider add the below code to each slider; function slider1_val_Callback(hObject, eventdata, handles) global C; C(1)=str2num(get(hObject,'string')); minn=get(handles.C1_var,'min');maxx=get(handles.C1_var,'max'); if(C(1)<minn || C(1)>maxx) C(1)=get(handles.C1_var,'value');set(hObject,'string',num2str(0)); else set(handles.slider1_var,'value',C(1)); end function slider1_val_CreateFcn(hObject, eventdata, handles) if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')) set(hObject,'BackgroundColor','black'); end

Repeat the above step for all 10 sliders


Add equalizer plot and filter function in the code. As the equalizer is of 10 band so we have to design 10 filters.


After adding the equalizer plot your design will be like this ;


So your design of 10 Band Audio Equalizer is ready now run the code


Thank You

Prepared by Hasham Khan [email protected]

NUST School of Electrical Engineering and Computer Science(SEECS)

mailto:[email protected]