Methods and systems for determining what channel a user is viewing through a TV receiver are described. At the TV receiver, a plurality of TV signals is received. A channel selection is received. The TV receiver tunes to the selected channel from among the plurality of TV signals. A watermark is inserted into a component of the tuned TV signal to form a modified TV signal, and the modified TV signal is output from the TV receiver. The watermark encodes meta-information associated with the tuned TV signal. In some implementations, the modified TV signal is received by a computer system. The watermark from the modified TV signal is processed to decode the meta-information, and the meta-information is provided to an application running on the computer system.