A method for estimating two or more physiological signals from a subject includes steps of a) obtaining a video input in the form of a sequence of frames of image data depicting the face and optionally the chest of the subject; b) providing the video input to a multi-head neural network model trained from a set of facial video inputs from a multitude of other subjects (such video inputs optionally including the chest), wherein the model has at least two heads and is trained to predict at least two physiological signals from a video input; and c) generating with the model data representing an estimate of the two or more physiological signals of the subject. In one embodiment the physiological signals are heart rate and respiratory rate. In one embodiment the multi-head neural network model is implemented in a smartphone having a camera which is used to capture the video input.