MATLAB: ??? Error: The expression to the left of the equals sign is not a valid target for an assignment.

vipin

 if obj=L;
         [y fs]=wavread('tl.wav');
            player=audioplayer(y,fs);
            play(player)
     else if  obj=R;
            [y fs]=wavread('tr.wav');
            player=audioplayer(y,fs);
            play(player)
         else if obj=F;
            [y fs]=wavread('mf.wav');
            player=audioplayer(y,fs);
            play(player)
             else if obj=B;
            [y fs]=wavread('mb.wav');
            player=audioplayer(y,fs);
            play(player)
                 else
                      [y fs]=wavread('s.wav');
            player=audioplayer(y,fs);
            play(player)
                 end
             end
         end
     end
    end

Best Answer

Hi,

your else if (in C code) conditions are badly written -> elseif in matlab code.

and the conditions are not conditions. you need to use == instead of =.

something like

if obj==L;
    [y,fs]=wavread('tl.wav');
    player=audioplayer(y,fs);
    play(player)
elseif  obj==R;
    [y,fs]=wavread('tr.wav');
    player=audioplayer(y,fs);
    play(player)
elseif obj==F;
    [y,fs]=wavread('mf.wav');
    player=audioplayer(y,fs);
    play(player)
elseif obj==B;
    [y,fs]=wavread('mb.wav');
    player=audioplayer(y,fs);
    play(player)
else
    [y,fs]=wavread('s.wav');
    player=audioplayer(y,fs);
    play(player)
end

Related Solutions

MATLAB: I want to find and hear the frequency responce of a .wav file using following equation y(n)=y(n-1)-0.9*y(n-2)+x(n)+x(n-1) but still its giving error in equation foolowing is the code

You need to use semi-colons to separate multiple commands in the same line. For example

player2=audioplayer(H, w, Fs) play(player2)

is not valid and needs to be

player2=audioplayer(H, w, Fs); play(player2)

MATLAB: Audioplayer

The audioplayer object is "scoped". Once no more references to the handle exist, it stops playing and cleans up itself. See Loren's blog:

http://blogs.mathworks.com/loren/2008/07/29/understanding-object-cleanup/

You need to save a copy of player someplace, but only long enough to let the sound play. You can use a timer with a callback to keep player in scope, and then have the timer callback delete player when it is done playing.

EDIT

Basically your variable player points to an audioplayer object. When there are no variables in memory that point to that audioplayer object, MATLAB deletes the object. MATLAB automatically takes care of the memory management. Your player variable gets deleted when your callback function exits (again MATLAB is taking care of the memory management). The key then is to either prevent your callback function from exiting until after the playing has finished or make sure a copy of player is "saved" someplace else.

The easiest is probably to replace

play(player)

with

playblocking(player)

A slightly better solution might be to do

 play(player);
 pause(max(size(y))/Fs);

The playblocking method will potentially block everything including callbacks. The pause method will allow callbacks to be processed. Both these methods, however, will halt the linear flow of the program until after the playback has finished. There are ways around this, but it depends on your program (see my comment to your question).

Best Answer

Related Solutions

MATLAB: I want to find and hear the frequency responce of a .wav file using following equation y(n)=y(n-1​​)-0.9*y(n​-​2)+x(n)+​x(​n-1) but still its giving error in equation foolowing is the code

MATLAB: Audioplayer

Related Question

MATLAB: I want to find and hear the frequency responce of a .wav file using following equation y(n)=y(n-1)-0.9*y(n-2)+x(n)+x(n-1) but still its giving error in equation foolowing is the code