Methods and apparatus to monitor audio/visual content from various sources are disclosed. An example method to monitor media content provided by a selected one of a plurality of media content sources for presentation by an information presenting device disclosed herein comprises determining first information based on a video signal corresponding to the monitored media content, determining second information based on an audio signal corresponding to the monitored media content, identifying the selected one of the plurality of media content sources based on a first classification decision resulting from one of the first information and the second information and a second classification decision resulting from the other of the first information and the second information, and identifying the monitored media content based on identification information associated with at least one of the video signal or the audio signal.