getframe problem

i am trying to make a video clip (avi) from a sequence of surf plots.

i used the getframe function to capture a series of figures depicting an evolvement of some data. a clip is created (through writeVideo). when i run the clip, instead of the full moving video i get a still image of the first frame mixed with my own desktop background details. this is a mess up coming from getframe.

any suggestions why this happens and how it could be overcome?

thanks a lot

mat

Answer 1

[Onomitra Ghosh]

You can try the workarounds mentioned in:

http://www.mathworks.com/support/bugreports/384622

[Lauren]

Hi Mat,

I was having the same problem you described. I used option 1 from the link above, and it seemed to solve the problem for me. In the code below, if I uncommented either of the two commented lines within the for loop, it would not work without changing the renderer to zbuffer. Once I added the line to set the renderer to zbuffer, I could uncomment either the surf or the mesh command in the for loop, and was able to produce the desired avi video clip.

clear all;
close all;
i_test = 25*pi/180;
theta = 0:0.1*pi:2*pi;
x_test = cos(theta);
y_test = cos(i_test)*sin(theta);
z_test = sin(i_test)*sin(theta);
[sphere_x,sphere_y,sphere_z] = sphere(25);
sphere_x = 0.5*sphere_x; 
sphere_y = 0.5*sphere_y; 
sphere_z = 0.5*sphere_z;
figure;
axis([-1.5,1.5,-1.5,1.5,-1.5,1.5]);
axis square;
title Title;
xlabel x; ylabel y; zlabel z;
hold on;
set(gcf,'Renderer','zbuffer') 
k_test = 1;
for t = 0:0.01*pi:2*pi
    cla;
    plot3(x_test,y_test,z_test,'-r',cos(t),cos(i_test)*sin(t),...
        sin(i_test)*sin(t),'ok');
%     surf(sphere_x,sphere_y,sphere_z,'EdgeColor','black',...
%         'FaceColor',[0,.5,0]);
%     mesh(sphere_x,sphere_y,sphere_z,'EdgeColor',[0,.5,0]);
    text(.6,-1.2,-1,['t = ' num2str(t)]);
    testMovie(k_test) = getframe(gcf);
    k_test = k_test + 1;
end

Answer 2

[Jan]

I had some success with adding a pause(0.02) before the getframe call. Using drawnow only helped in 99% of the pictures only.

Answer 3

[Bruno]

It works with me.

Answer 4

[Jeremy]

I'm having a similar problem, when I call movie(F), I get only the first frame of the video, then the call to movie ends. (Matlab 2015b, on Mac OS X 10.10.5). Any ideas?

(Also, the frame it shows is off center on the plot and partially hidden, not sure if this is relevant or not)

***Update: Never mind, I was accidentally skipping frames, so my F matrix had only every fourth entry filled in, I guess the empty entries stopped it.