SPDIF is a format for transmitting digital audio between components like DVD players and HDTVs. Some components have both SPDIF and digital coaxial jacks; the cables for these different connections are not compatible with each other.
SPDIF
SPDIF stands for "Sony/Philips Digital Interconnect Format." It transmits audio as a 32-bit data stream in either two-channel stereo audio or Dolby Digital surround sound. As SPDIF is a transmission protocol, it is not dependent on a specific connection type, but it usually uses an optical TOSLINK digital audio connection.
Connection Types
Both SPDIF optical and digital coaxial cables can relay audio. Coaxial cables look like thicker RCA cables; they transmit audio as pulses of electricity through a copper wire. SPDIF optical cables transmit audio as pulses of light, eliminating the interference and degradation that can occur with digital coaxial cables, especially over long distances.
Incompatibility
SPDIF and digital coaxial jacks use different methods to transmit data; you cannot substitute one for the other. TOSLINK SPDIF cables also use a differently-shaped connector than digital coaxial cables: coaxial cable connectors are round, while TOSLINK optical cables use a square plug.
Tags: digital coaxial, digital coaxial cables, audio pulses, coaxial cables, coaxial jacks, digital audio