I think you should take a look at "Eulerian Video Magnification", a method for magnifying imperceptibly small motions in a video that was invented by the CSAIL lab at MIT. In the process of doing this, they use a variety of signal processing techniques that may be useful to you. By using this technique, the researchers have been able to extract things like pulse rate and breathing rate of people simply by processing a video of the subject.
The code to use their algorithm is posted in the link below.
http://people.csail.mit.edu/mrub/vidmag/