The method we have been using is making simple speed color coded line with small dot every 10 secs and large dot every minute. Very easy to spot and count time losses just by looking at this plain image if you zoom in enough. Works very well in doma with smartphones.
What are tho options if I like to do something similar. Is there anything like this available for Android - I can find some apps but those quite doesn't do it, at least not any better than QR.