Patent ID: 8351624

Claim:
An audio output apparatus which outputs an audio signal to an audio control apparatus controlling processing of the audio signal, the audio output apparatus being connectable to an external device having an external terminal, the audio output apparatus comprising: an output terminal to which the external terminal is connected and which outputs the audio signal to the external device via the external terminal; a detecting means for detecting whether or not the external terminal is connected to the output terminal; a generating means for generating a control signal based on a result of the detection by the detecting means; and a transmitting means for transmitting the control signal to the audio control apparatus in order that the audio control apparatus controls the processing of the audio signal based on the control signal, the control signal being transmitted via a hot plug detect line and a reserve line connected as a differential twisted pair, the control signal being selectable from among at least four possible signals including a first signal specifying that recording is permitted and that the external device is connected, a second signal specifying that recording is permitted and that the external device is not connected, a third signal specifying that recording is not permitted and that the external device is connected, and a fourth signal specifying that recording is not permitted and that the external device is not connected.