Methods and apparatus to distinguish a signal originating from a local device from a broadcast signal are disclosed. A disclosed system classifies a video component of an audio-video signal by analyzing a histogram of pixel data, analyzing a quality factor, and/or attempting to detect embedded data in the video component. The disclosed system also classifies an audio component of the audio-video signal by attempting to detect embedded audio data and/or analyzing waveform energy associated with the audio component. A source of the audio-video signal is determined based on the video classification and/or the audio classification.