What is S / PDIF?
S / PDIF is a type of data link layer and a physical layer for transmitting digital audio signals between multiple devices or stereo components. S / PDIF is an acronym for Sony / Philips Digital Interconnect Format or Sony Philips Digital Interface. As described in the acronym, the S / PDIF format was developed during joint operations between Sony and Philips. This is a minor adjustment to the AES / EBU (Audio Engineering Society / European Broadcasting Union) specification from 1985. Unlike the AES / EBU, the S / PDIF format was developed specifically for home, consumer use, because it is hardware required is not as expensive as the AES / EBU model requires.
What is S / PDIF used for?
S / PDIF is used to transfer digital audio to a variety of home audio equipment. Common devices that can use the S / PDIF format include: DVD players, computer sound cards, CD players and receivers. The most common connection is between a DVD player and a receiver for high quality Dolby Digital or DTS surround sound. However, it is also quite common to connect a CD player with an S / PDIF cable to a receiver.
What are the differences between the AES / EBU standard and S / PDIF?
The AES / EBU standard provides the building blocks for what would become S / PDIF. The two formats differ in their use of cables, connections, signal level, subcode information and maximum resolution. However, both formats use two-phase tagging for modulation.
The AES / EBU format uses a more robust 110 ohm shielded cable, while the S / PDIF format uses a more consumer-friendly 75 ohm coaxial cable or fiber cable. AES / EBU can also use a 75 ohm coaxial cable. The AES / EBU format can benefit from XLR, D sub or BNC connections, while the S / PDIF format uses RCA, BNC or TOSLINK connections.
The signal level found at the AES / EBU specification ranges from 3 to 10 volts, while the S / PDIF signal level varies from 0.5 to 1 volts. Subcode information is provided via ASCII ID text for AES / EBU, while subcode information is provided via SCMS for S / PDIF. Furthermore, the maximum resolution for AES / EBU is 24 bit, while the S / PDIF format provides only a maximum resolution of 20 bit.
What are the other specifications for S / PDIF?
The most common frequency of digital signal transmission over S / PDIF is 48 kHz for DAT (Digital Audio Tape) or 44.1 kHz for CD quality audio. There is no defined data rate for S / PDIF, which instead uses a biphasic tag code that allows one or two transitions for each part.