SPDIF, also written as S/PDIF, stands for Sony/Phillips Digital Interface, and is an interface to transmit digital audio. In this tutorial, we will explain everything you need to know about this interface, including when and how to use it.

Digital audio means that the audio signal is transmitted encoded in a series of 0s and 1s instead of being transmitted in analog format. This makes audio have higher fidelity, because no noise will be added to the audio signal. Therefore, it is always better to transmit audio in digital format.

Currently, there are two consumer-level interfaces to transmit audio in digital format: SPDIF and HDMI (High-Definition Multimedia Interface). SPDIF transmits only audio, but HMDI also carries digital video signal.

If HDMI is a more “complete” interface, why should you use SPDIF? It’s because not all audio/video equipment has an HDMI output available. For example, a professional-grade CD player or a MiniDisc deck will have an SPDIF output available, but not an HDMI, since this equipment doesn’t produce video, only audio. Also, in certain situations (which we will talk about in the next page), you will need to carry video using the HDMI interface but audio using an SPDIF connection. Also, SPDIF cables and connectors are very thin, while HDMI cables and connectors are bulky, since they have more wires inside.

Let’s talk about when the SPDIF connection is to be used.