Thank you for you help, Sean and Liviu.
The new MovieEncoder didn't solve my problem, but thanks to your
explanation, I was able to halt my program for 25ms before calling the
stop()-method of the MovieEncoder - all images are now included in the
movie!!!

I have another question - not sure whether this is due to the
MovieEncoder or JMF, but hopefully you may have an idea.
I can now successfully create movies from datafiles, which are outputs
of a model. I would also like to write out movies "on the fly", while
the model is running - like you do with MASON.
I'm using the same writer class (which calls on MovieEncoder) and I'm
not aware that our model framework (though I don't know the ins and outs
of it) uses any applets, yet I get the following error:

     [java] java.lang.RuntimeException: No permission to write files
from applets
     [java]     at
com.sun.media.JMFSecurityManager.checkFileSave(JMFSecurityManager.java:250)
     [java]     at
com.sun.media.datasink.file.Handler.open(Handler.java:219)
     [java]     at sim.util.media.MovieEncoder.setup(MovieEncoder.java:322)
     [java]     at sim.util.media.MovieEncoder.<init>(MovieEncoder.java:161)

when I'm creating a new instance of the MovieEncoder.

Regards,
Anja