SPDIF is a consumer orientated digitial audio interface standard developed jointly by Sony and Philips to enable direct digital interconnections to be made between separate items of digital audio equipment. SPDIF (pronounced "es-pee-dif") is a acronym for S ony P hilips D igital I nter F ace and is sometimes also abreviated S/PDIF or even S-PDIF. SPDIF audio interfaces can be found at the rear of most digital audio recorders (MiniDisc, DAT and DCC) and also a few CD and CDROM players as well.

Physically the connection between SPDIF compatible units can be made using optical fibre and optical "TosLink" modules, or electrically using coaxial cable and RCA/Phono type connectors. There are some exceptions to this with some types of equipment requiring different connectors (DAT uses balanced cable & XLR connectors, some portable recorders use 3.5mm optical mini-jack plugs) or different voltage levels to indicate the Logic '0' and Logic '1' binary values.

Most computer sourced electrical SPDIF signals (Soundcard, CDROM drive) have TTL compatible voltage levels (0V=Logic '0', greater than 3.5V=Logic '1'), but some share the normal consumer Hi-Fi audio coaxial electrical standard level using 0V as logic '0 and 0.5-1V as logic '1' .

More info on the SPDIF data format and clock rates.