Sony/Philips Digital Interface Format, popularly SPDIF is basically a collection of hardware and low-level protocol specifications which carry digital audio signals between various devices and stereo components. As obvious from its name, Sony and Philips are two companies which are particularly concerned about the design aspects of the SPDIF. The most important feature SPDIF is that it requires less expensive hardware as compared to other Digital Interface formats in its family. Usually, you will find SPDIF on digital audio equipments.

A great example of such Audio Equipment is the Digital Audio Tape or the DAT machine which allows the transfer of audio signals from source to destination without converting the signal into analog format. This ensures the quality of the audio files upon the completing of the transfer process.

Usually SPDIF is used for transmitting 20 bit Audio Signals, though it is also capable of transmitting upto 24 bit audio signals. They use 75 ohm coaxial cable and RCA connectors. The advantage of using 75 ohm coaxial cable is that it is inexpensive as it is the same cable which is used in video transmission. We also have an optical version of SPDIF known as the TOSLINK which uses the Toslink Optical Components. An important feature here is that the signals are transmitted using visible light. These optical signals have same format as that of electrical SPDIF, the only difference being that they are now transmitted as light signals.

The most common Example of devices where SPDIF are mostly used is the CD or the DVD players. But you will also find them in many Digital audio devices. They are also very popular in the Digital Video Broadcast Receivers and Audio Devices used in cars and other big vehicles. SPDIF is also used in the connectors that connect your Home Theater and your DVD player. So, basically you find SPDIF in almost all common Digital Audio devices.