View source for S/PDIF

==== IEC 61937 encapsulation ====
IEC 61937 defines a way to transmit compressed, multi-channel data over S/PDIF.<ref>Digitalton - Schnittstelle für nichtlinear-PCM-codierte Audio-Bitströme unter Verwendung von IEC 60958 - Teil 1: Allgemeines (IEC 61937-1:2007 + A1:2011); Deutsche Fassung EN 61937-1:2007 + A1:2011</ref>

* The control word bit 0:1 is set to indicate the presence of non-linear-PCM data.
* The sample rate is set to maintain the needed symbol (data) rate. The symbol rate is usually 64 times the sample rate.
* Data is packed into blocks. Each data block is given an IEC 61937 preamble, containing two 16-bit sync words and indicating the state and identity (type, validity, bitstream number, length) of encapsulated data present. Padding is added to match the full block size as required by timing.

A number of encodings are available over IEC 61937, including Dolby [[Dolby Digital|AC-3]]/[[E-AC-3]], [[Dolby TrueHD]], MP3, AAC, [[ATRAC]], [[DTS Coherent Acoustics|DTS]], and [[WMA Pro]].<ref>{{cite web |title=FFmpeg: libavformat/spdif.h File Reference |url=https://ffmpeg.org/doxygen/trunk/spdif_8h.html |website=ffmpeg.org}}</ref><ref>{{cite web |title=Representing Formats for IEC 61937 Transmissions - Win32 apps |url=https://learn.microsoft.com/en-us/windows/win32/coreaudio/representing-formats-for-iec-61937-transmissions |website=learn.microsoft.com |language=en-us |date=15 May 2023}}</ref>