AV.link

AV.link (also known as Audio Visual Link or sometimes as Control-A) is a proprietary communication protocol utilized primarily in older consumer electronics, particularly those manufactured by companies like Philips and Grundig. It allows connected devices, such as televisions, VCRs, DVD players, and set-top boxes, to communicate basic control commands with each other over a 7-pin DIN connector.

Functionality:

AV.link enables features such as synchronized recording, playback, and power control. For example, when a VCR connected via AV.link is put into record mode, the television can automatically switch to the appropriate input channel. Similarly, when a DVD player is started, it can signal the television to turn on or switch to its input.

Technical Details:

The protocol uses a serial data stream transmitted over one or more of the pins in the 7-pin DIN connector. The signals are generally simple on/off commands rather than complex data transfers. Different manufacturers may have implemented slightly different variations of the protocol, leading to potential compatibility issues between devices from different brands, despite their adherence to the AV.link standard.

Alternatives and Obsolescence:

AV.link has largely been superseded by more robust and versatile standards such as HDMI-CEC (Consumer Electronics Control), which allows for bi-directional communication and a wider range of control options. Due to the limitations and age of the protocol, AV.link is rarely found in modern consumer electronics. Its primary relevance is in understanding and maintaining older audio-visual systems.