saving figures to a video with VideoWriter

when triyng to plot some data and save the figures to creat video file, i get this error:

i tried to debug the code and coulndnt find a way to fix it.

this is my code:

fs = 250;
t = 0:1/fs:3;
signal_freq = 0.5;

h1 = animatedline('Color','b','Linewidth',1.5);
h2 = animatedline('Color','r','Linewidth',1.5);
y = 180*sin(2*pi*signal_freq*t);
ycos = 180*cos(2*pi*signal_freq*t);

frames = cell(length(t),250/5);
for i= 1:5:length(t)-4
   
    tvec = t(i:i+4);
    yvec = y(i:i+4);
    ycosvec = ycos(i:i+4);
    addpoints(h1,tvec,yvec);
    addpoints(h2,tvec,ycosvec);

    drawnow;
    frames{i} = getframe(gcf);
    
    xlim([0 max(t)+1]);
    ylim([-200 200]);
    legend("sin","cos");
    grid on;
end

obj = VideoWriter("myvideo","MPEG-4");

The specified profile is not valid.

obj.Quality = 100;
obj.FrameRate = 50;
open(obj);

for i=1:length(frames)
    writeVideo(obj,frames{i})
end
obj.close();

Answer 1

[Walter Roberson]

getframe() with no options is not guaranteed to return the same size each time. In practice the size of an axes can vary by (if I recall correctly) up to 7 pixels, mostly depending on the labels. You do not xlim or ylim before looping adding points, so the tick locations are being dynamically changed as you go, and that affects the axes width.

[Eyal Sasson]

thank you