Let us make a smart surveillance camera using a Raspberry Pi single board computer. Normally, it records the videos at 5x speed analyzing continuously and producing video files daily or hourly. Once human bodies are detected in the captured images, it will highlight them with green rectangles and change the recording speed to normal. A passive infrared sensor (PIR sensor) is also used to detect human bodies.
The example program discussed here is just to show the feasibility and it can be improved further.
A few examples are sending email to your email address if something happened, recognition of faces of family members, recording videos at different speeds depending on time.