This technical standard is usually referred to as HD-SDI; it is part of a family of standards that define a serial digital interface based on a coaxial cable, intended to be used for transport of uncompressed digital video and audio in a television studio environment.
Such fears have not been realized, and the optical interfaces are seldom if ever used, and are likely to be deprecated in future revisions of the standard.
Framing is done by detection of a special synchronization pattern, which appears on the (unscrambled) serial digital signal to be a sequence of twenty ones followed by forty zeroes; this bit pattern is not legal anywhere else within the data payload.
The SMPTE 292 digital interface is known to be reliable (without use of repeaters) at cable lengths of 100 m or greater.
These reserved words have two purposes, for synchronization packets, and for ancillary data headers.
The first three words are always the same—0x3FF, 0, 0; the fourth consists of 3 flag bits, along with an error correcting code.
Ancillary data is provided as a standardized transport for non-video payload within a serial digital signal; it is used for things such as embedded audio, closed captions, timecode, and other sorts of metadata.
Ancillary data is indicated by a 3-word packet consisting of 0, 3FF, 3FF (the opposite of the synchronization packet header), followed by a two-word identification code, a data count word (indicating 0 - 255 words of payload), the actual payload, and a one-word checksum.
For portions of the vertical and horizontal blanking regions which are not used for ancillary data, it is recommended that the luma samples be assigned the code word 64 (40 hex), and the chroma samples be assigned 512 (200 hex); both of which correspond to 0 mV.
On July 31, 2013 it was announced that SMPTE won a Technology & Engineering Emmy Award for 2013 by the National Academy of Television Arts and Sciences.
The honor recognized the society’s work on development, standardization, and productization of SMPTE 292.