Multimedia audio-video system and protocol converter therefor

A multimedia system and a protocol converter are provided. The multimedia system includes a sink device, e.g., a television, various audio-video devices connected to the sink device, and the protocol converter. The protocol converter connects to the sink device. The protocol converter processes the audio and video signals inputted from a specific audio-video source that are configured to be played in the sink device, and the audio signals can be processed and played by an audio playback device that is directly connected with the protocol converter. Furthermore, the protocol converter can process the audio signals that are received from an audio acquirement processing device by the sink device and returned to the audio acquirement processing device via an audio return channel or an enhanced audio return channel. At last, the received audio signals are converted and outputted to one of various audio output interfaces supported by the protocol converter.