1. A method of identifying a media source, comprising: generating first signature information based on media presented via a media delivery device; comparing the first signature information to second signature information, wherein the second signature information is derived from a library of signature information local to the media delivery device; generating a collection of matching signature information based on the comparison of the first and second signature information; identifying a source of the media presented via the media delivery device based on the collection of matching signature information; and performing a time shift analysis on the collection of matching signature information by identifying records in the collection of matching signature information having substantially identical signature values and substantially different time stamp values.