not easy, once sanch and me came up with the idea to record the fft data with time stamps into a textfile and read it with a time function during the rendering. but first i would try to record the vvvv output with a cam, or other recorder…
btw: with the DoSeek pin of the FileStream node and the right video codec its possible to include video in non real time rendering. what will a mp3 file do here? try: