Changing the animation length of exported file

Question

Below is the code i used to generate a point travelling a parametric plot

a = 5
b = 6
c = 1
plot2d = Show[
Table[ParametricPlot[{a Cos[t] - c, b Sin[t]}, {t, 0, 2 Pi}], {i, 
 1}], Graphics[{Point[{0, 0}]}], ImageSize -> 500];
ani=Manipulate[
 Show[plot2d, 
 Graphics[{Red, PointSize[0.03], 
Point[Table[{a Cos[t] - c, b Sin[t]}, {i, 1}]]}]], {t, 0, 2 Pi}]

When i use the code to export as an avi file;

Export["trial.avi",ani]

I get a 4 second animation, even if i try to alter the frame rate or duration of the animation, i still end up with a 4 second avi file. Is it possible to generate and export this as a 30 second avi file?

Answer 1

Using Table allows control of the frames. Here is an example with step size Pi/200, resulting in a 27 second video.

a = 5;
b = 6;
c = 1;
plot2d = Show[Table[ParametricPlot[{a Cos[t] - c, b Sin[t]}, {t, 0, 2 Pi}], {i, 1}], Graphics[{Point[{0, 0}]}], ImageSize -> 500];

ani2 = Table[Show[plot2d, Graphics[{Red, PointSize[0.03], 
      Point[Table[{a Cos[t] - c, b Sin[t]}, {i, 1}]]}]], {t, 0, 2 Pi, Pi/100}];

Export["trial.avi", ani2]

If you really want to see the animation slider for t, you can use:

ani3 = Animate[
  Show[plot2d, Graphics[{Red, PointSize[0.03], 
     Point[Table[{a Cos[t] - c, b Sin[t]}, {i, 1}]]}]], {t, 0, 2 Pi}]

Export["trial.avi", ani3, "AnimationDuration" -> 15]

This results in a 15 second video (change the value of "AnimationDuration" to make it longer).