13. A method comprising: receiving, in a portable audio device, audio data representing samples of audio content, for rendering into human-perceptible sound; applying a digital watermark decoding or audio fingerprinting algorithm to the received audio data to derive identification data therefrom; by reference to the derived identification data, selecting a favored software program for rendering of said audio data into said human-perceptible sound, said selecting being performed by a processor in the portable device that is configured to perform such act; and indicating the favored software program to a user; wherein the favored software program for rendering the audio data is selected based on identification data derived from the audio data.
13. A method comprising: receiving, in a portable audio device, audio data representing samples of audio content, for rendering into human-perceptible sound; applying a digital watermark decoding or audio fingerprinting algorithm to the received audio data to derive identification data therefrom; by reference to the derived identification data, selecting a favored software program for rendering of said audio data into said human-perceptible sound, said selecting being performed by a processor in the portable device that is configured to perform such act; and indicating the favored software program to a user; wherein the favored software program for rendering the audio data is selected based on identification data derived from the audio data. 15. The method of claim 13 in which said favored software was designated by a creator of the audio content.