1. Time delay neural network apparatus for outputting a trajectory in response to an input label frame wherein the trajectory is represented as a temporally related sequence of frames, each frame including a plurality of feature elements, the apparatus comprising, an input layer means for connecting the input label frame to at least a first hidden layer means, first layer means for oversampling constrained features from its respective input to generate the trajectory related to the input label frame, wherein the first layer means is constrained.