For generating a breathing alert, a method captures a video stream of a subject. The method further generates a vector time series that includes a vector for each image frame of the video stream. The method estimates of breathing signal from the vector time series. The method further determines one of large-scale motion and a breathing event of the subject based on the breathing signal. The method generates an alert if no breathing event is identified and no large-scale motion of the subject is identified within an event time interval.
