Combining image, sound and TTL

[jarvis24]

[edited from a related support email]

I have programmed an experiment in which we show participants a series of muted video clips. Some of the videos are paired with a startle sound that is meant to scare the participants a bit. The videos are in AVI format and are playing fine. The startle sound is a windows media sound file, and is also played without a problem by DirectRT.

Unfortunately I have stumbled into a problem. As soon as the startle sound file plays, the movie stops playing. This is a problem because I want to play the startle sound at different points. For instance, for a 9 second video, sometimes the startle will come at the 5th second, for other participants it may come at the 6th or 7th, but the movie should continue playing after the startle sound (which is very brief, about 500 miliseconds). How could I bypass this problem? Is it because directRT uses Windows media to play the movie and the sound files? Any help would be greatly appreciated.

You may be able to do this by playing the sound first if you create multiple versions of the sound file--each with varying lengths of silence to start, and with time values of "0,0,0" so there is no delay between the onset of the sound file and of the video. See if the response and sample above help.