1. A method of assessing the perceptual quality of multimedia content provided over a communications channel, comprising the steps of: incorporating a plurality of digital watermarks in the multimedia content; transmitting the multimedia content including the plurality of digital watermarks over the communications channel, each of the plurality of digital watermarks having an associated level of robustness with respect to at least one specified type of potential degradation of the respective digital watermark; detecting at least one of the plurality of digital watermarks in the multimedia content; and in response to having detected at least one of the plurality of digital watermarks in the multimedia content, generating an output indicative of at least the quality of the multimedia content based at least in part on the level of robustness of the at least one detected digital watermark.