What is S/PDIF connect and Digital Audio Out
There are two SPDIF standards by connector type, copper and optical. These two standards are the same in terms of encoding type. The difference is that Digital Audio Out SPDIF uses copper cable to transmit, while Optical SPDIF uses optical fibre to transmit audio.
These outputs were developed jointly by Sony and Philips for use in TVs and other audio devices. They are used to transmit audio, for example, from a television to an external active speaker. Initially, SPDIF supported audio transmission in stereo format, without compression. After further refinement, SPDIF supports the output of sound in 5.1, 7.1, and compressed formats.
This format for digital video transmission emerged in the 1990s. When audio began to be recorded digitally on CDs, the question arose as to how audio could be digitally transmitted to the speakers without additional conversion. Originally, SPDIF was developed to transmit audio from DVD players to speakers. SPDIF solved this problem, and subsequently a large number of devices began to support the format. SPDIF is used in televisions, in the form of an optical output. Later on, similar audio transmission options, such as HDMI ARC, have emerged.
Digital Audio Out explained
Digital audio out -This output is in the form of the familiar plug since the days of analogue television, the correct name is RCA. The devices are connected to each other with a coaxial cable, the sound is transmitted digitally using special protocols. The approximate maximum cable length between the devices is 10 metres (32 feet). But the maximum cable length depends on the quality of the materials used and the manufacture of the cable.
Optical SPDIF (Sony Philips Digital Interface Format) optical audio output explained
optical S/PDIF (Sony/Philips Digital Interface Format)– in this case, the sound is transmitted using a laser over an optical cable between the devices. The power of the transmitted optical signal is such that the maximum possible distance between the devices is also about 10 metres. There is a connector on the device, usually called TOSLINK.
Optical SPDIF vs Digital Audio Out SPDIF
These outputs are the same in terms of the quality of the transmitted signal, only in the first case an optical signal is used as the signal transmission medium, in the second case a physical signal is used. In both cases, the audio signal is transmitted digitally and is not subject to distortion or attenuation. Unlike the analogue signal, which is distortion-prone and fades unevenly at different frequencies, the higher the frequency the more the signal fades. Both SPDIF formats are used quite a lot, optical in TVs, physical interfaces are more common in computers.
Other ports for digital audio transmission
Similar connections for the transmission of digital audio are not numerous, one of the main tasks of such protocols is the transmission of DTS or Dolby digital multichannel audio from one device to another. Similar functions are performed by the HDMI port and a variant of HDMI ARC, Display Port. But these are protocols that combine video and audio transmission, SPDIF is purely an audio transmission format.