A server machine and a first device (e.g., a television) are configured to access a stream of media (e.g., a broadcast channel) from a media source (e.g., a broadcaster). The server machine generates a representation (e.g., a fingerprint) of the stream of media and stores the representation. The first device plays the stream of media (e.g., for a user) and generates an analog signal based on the stream of media. A second device (e.g., a mobile device of the user) is configured to receive the analog signal and generate a representation of the analog signal. The second device provides the representation of the analog signal to the server machine, which may compare the representation of the stream of media to the representation of the analog signal. Based on the comparison, the server machine may provide an identifier of the media source to the second device.