Frame Differencing With Kinect

Hi all,

How would I go about calculating and storing the differences between the kinect depth stream throughout each frame? I am hoping to achieve a final plot representing depth vs time.

Code so far:

depthVid = videoinput('kinect', 2);
framesPerTrig = 100;
depthVid.FramesPerTrigger = framesPerTrig;
start(depthVid)

[frame, ts, metadata] = getdata(depthVid)

For simplicity the plot can represent just one pixel, lets say the pixel with x y coordinates 480 x 200 (kinect resolution is 512 x 424) in the whole image.

Thank you in advance for your help!