Editing Serial digital interface (section)

===Bit rates===
Several bit rates are used in serial digital video signal:

* For [[standard-definition]] applications, as defined by SMPTE 259M, the possible bit rates are 270&nbsp;Mbit/s, 360&nbsp;Mbit/s, 143&nbsp;Mbit/s, and 177&nbsp;Mbit/s. 270&nbsp;Mbit/s is by far the most commonly used; though the 360&nbsp;Mbit/s interface (used for [[widescreen]] standard definition) is sometimes encountered. The 143 and 177&nbsp;Mbit/s interfaces were intended for transmission of composite-encoded ([[NTSC]] or [[PAL]]) video digitally and are now considered obsolete.
* For [[enhanced definition television|enhanced definition]] applications (mainly 525P), there are several 540&nbsp;Mbit/s interfaces defined, as well as an interface standard for a dual-link 270&nbsp;Mbit/s interface. These are rarely encountered.
* For [[HDTV]] applications, the serial digital interface is defined by SMPTE 292M. Two bit rates are defined, 1.485&nbsp;Gbit/s, and 1.485/1.001&nbsp;Gbit/s. The factor of 1/1.001 is provided to allow SMPTE 292M to support video formats with frame rates of 59.94&nbsp;Hz, 29.97&nbsp;Hz, and 23.98&nbsp;Hz, in order to be compatible with existing [[NTSC]] systems. The 1.485&nbsp;Gbit/s version of the standard supports other frame rates in widespread use, including 60&nbsp;Hz, 50&nbsp;Hz, 30&nbsp;Hz, 25&nbsp;Hz, and 24&nbsp;Hz. It is common to collectively refer to both standards as using a nominal bit rate of 1.5&nbsp;Gbit/s.
* For very high-definition applications, requiring greater resolution, frame rate, or color fidelity than the HD-SDI interface can provide, the SMPTE 372M standard defines the '''dual link''' interface. As the name suggests, this interface consists of two SMPTE 292M interconnects operating in parallel. In particular, the dual link interface supports 10-bit, 4:2:2, 1080P formats at frame rates of 60&nbsp;Hz, 59.94&nbsp;Hz, and 50&nbsp;Hz, as well as 12-bit color depth, RGB encoding, and [[Chroma subsampling#4:4:4|4:4:4]] colour sampling.
* A nominal 3&nbsp;Gbit/s interface (more accurately, 2.97&nbsp;Gbit/s, but commonly referred to as "3 gig") was standardized by SMPTE as 424M in 2006. Revised in 2012 as SMPTE ST 424:2012, it supports all of the features supported by the dual 1.485&nbsp;Gbit/s interface but requires only one cable rather than two.