Error using getframe.

Hi, I am trying to program an AVI on a crank-slider mechanism, but it keeps on showing up this error:

"Error using getframe (line 53)"
"A valid figure or axes handle must be specified"
"Error in Animation (line 33)"
"F=getframe(1);"

I am really new to matlab, so I can't seem to resolve this error.

w = 1.25;
Ampl = 10;

t = [0:1/30:10];

Px = Ampl*cos(w*t);
Py = Ampl*sin(w*t);

AVI = 1;
M_Movie = 0;

if AVI==1
    Rotation_Movie = VideoWriter('Rotation_Movie.avi');
    open(Rotation_Movie);
end;

for k = 1:length(t);

      plot(Px,Py);
      hold on;
      plot(Px(k),Py(k),'r.','MarkerSize',25);

      if k > 5;
          plot(Px(k-1),Py(k-1),'r.','MarkerSize',20);
          plot(Px(k-2),Py(k-2),'r.','MarkerSize',15);
          plot(Px(k-3),Py(k-3),'r.','MarkerSize',10);
          plot(Px(k-4),Py(k-4),'r.','MarkerSize',5);
          plot(Px(k-5),Py(k-5),'r.','MarkerSize',1);
      end;
      hold off;

      F=getframe(1);

      if(AVI);
          writeVideo(Rotation_Movie,F);

      elseif (M_Movie)
          E_movie(k)=F;
      end;

end;

if(AVI);
    close(Rotation_Movie);
end;

Answer 1

[Geoff Hayes]

Hariharan - rather than using 1 as an input to getframe, why not try using gcf to get the handle to the current figure (which may not be '1' for whatever reason)? Replace your above with

 F=getframe(gcf);

[Walter Roberson]

I suspect gca would be better than gcf

[HARIHARAN HEMARAJAN]

Yes, you are right. The error resolved, but I made it wheel spin round and round. How to I get it to go back and forth like a crank-slider would do? Thank you.

[Geoff Hayes]

Hariharan - back and forth from which point? Do you mean to say that if the Marker reaches a certain angle (relative to the origin) of the circle then it should change direction and so bound back and forth between two points?