1. A method of processing audio or video data, comprising: providing input content data, the content data representing audio or video and comprising plural samples, each having a value; providing plural symbol auxiliary data that is to be steganographically encoded within the content data, to yield encoded content data; receiving first data related to human perception attributes of the content data; generating intermediate data that is a function of said plural symbol auxiliary data and said first data, the intermediate signal including an element corresponding to each of plural of the content data samples; steganographically encoding the content data with the auxiliary data by changing the values of samples in a version of the input content data in accordance with elements of the intermediate signal corresponding thereto, thereby yielding the encoded content data; the method further including: assessing the input content data to discern biases inherent therein; and if a bias tends towards a change that would be made by said encoding, then changing the content data relatively less in correspondence thereto.