The disclosure relates generally to audio and video signal processing. One claim recites a method comprising: receiving audio or video content, wherein the audio or video content comprises a hidden steganographic code including information, the steganographic code being hidden in the audio or video content through alterations to data representing the audio or video content; detecting the steganographic code to obtain the information, said act of detecting utilizes correlation to obtain the information; providing at least a portion of the information to a data repository to identify machine-executable instructions stored therein; providing data associated with a user to the data repository; receiving machine-executable instructions from the data repository; and executing the machine-executable instructions to control processing of the audio or video content. Of course, other claims and combinations are provided too.