Simultaneous movie and image presentation

Programming Help
2

By default, if you are using Screen('GetMovieImage') then this will “block” waiting for the next frame, and your timing will be dictated by the frame rate of the movie. You could make your Flip times a multiple of the movie frame rate. But another solution requires not using blocking mode and using a second buffer texture. If Screen('GetMovieImage') returns a new frame, show that, if not, show the previous frame.

My movieStimulus class uses this technique (this is an OOP class and so me refers to itself):

me.blocking = false;
me.texture = Screen('GetMovieImage', me.sM.win, me.movie, me.blocking);
if me.texture > 0
	if ~isempty(me.buffertex) && ...
			me.buffertex > 0 && ...
			me.buffertex ~= me.texture && Screen(me.buffertex,'WindowKind') == -1
		try Screen('Close', me.buffertex); end
		me.buffertex=[]; 
	end
	Screen('DrawTexture', me.sM.win, me.texture, [], me.mvRect,...
		angle,[],[],[],me.shader);
	me.buffertex = me.texture; %copy new texture to buffer
elseif me.buffertex > 0
	Screen('DrawTexture', me.sM.win, me.buffertex, [], me.mvRect,...
		angle,[],[],[],me.shader)
end

Roughly it checks if texture is > 0 (a new frame): if so check if a previous buffertex is present and close it, then draw the new texture and assign it to buffertex | otherwise just draw buffertex. Now the timing is only dictated by Screen('Flip'), and so your other animations will work fine.You can see this in action easily with my toolbox:

m = metaStimulus;
m{1} = dotsStimulus('xPosition', 4, 'mask', true);
m{2} = movieStimulus('blocking', 0);
m.run; %test run of the stimuli

This creates a movie and an RDS stimulus, then runs them together at the FPS of the monitor display; the movie does not hold up the timing of the RDS…