Example apparatus disclosed herein are to obtain, from a network monitor, an address associated with one or more network communications used to convey a media stream to a first input device of a plurality of input devices in communication with a media device, query one or more data structures based on the address to identify a first input source of the media device, the one or more data structures to map respective ones of the plurality of input devices to corresponding ones of a plurality of input sources of the media device, the plurality of input sources including the first input source, obtain a watermark from a meter that is to monitor an output of the media device, and identify the first input source of the media device as associated with media presented by the media device in response to determination that the watermark corresponds to the media stream.