1. A computer-implemented method for estimating perceptual video quality, the method comprising: selecting a set of objective metrics that represent a plurality of deterministic video characteristics; for each training video included in a set of training videos, receiving a subjective value for a perceptual video quality metric and a set of objective values for the set of objective metrics, wherein the subjective value and the set of objective values describe the training video; deriving a composite relationship based on a correlation between the subjective value, the set of objective values, and a measure of pixel motion within at least one of the set of training videos, wherein the composite relationship specifies a level of contribution for at least one of the set of objective metrics to the perceptual video quality metric; for a target video, calculating a first set of values for the set of objective metrics; and applying the composite relationship to the first set of values to generate an output value for the perceptual video quality metric.