9. ICMP
3G
9.6 ICM P S DI specifications
3G-SDI
Serial Digital Interface (SDI) is a serial link standardized by ITU- R BT.656 and the Soc iety of Motion Picture and Tele-
vision Engineers ( SM PT E). SDI transmits uncomp ressed digital video over 75-ohm coaxial cable within studios, and
is seen on most professional video infrastructure equipment. T he first revision of the standard, S MP TE 259M, was
defined to carry digital representation of analog video such as N TS C and PAL ov er a serial interface and is more po p-
ularly known as standard-definition (SD) SD I. The data rate required to transmit SD SDI is 270 Mbps. With the advent
of high-definition (HD) video standards such as 1080i and 720p, the interface was scaled to handle higher data rates
of 1.485 Gbps . The 1.485-Gbps serial interface is commonly called the HD SDI interface and is defined by SMPTE
292M, using the same 75-ohm c oaxial cable. Studios an d other video production facilities h ave invested heavily on
the hardware infrastructure for coaxial cable and have a vested interest in ex tending the life of their infrastructure. For-
tunately, SMPTE recently ratified a new standard called SMPT E 424M that doubles the SDI data rates to 2.97 Gbps
using the same 75-ohm coaxial cable. This n e w standard, also called 3-Gbps (3G )-SDI, enables higher resolution of
picture quality required for 1080p and digital cinema.
SDI terminology
Standard H D- SDI signal
Single Link
1.5Gb/s HD 4:2:2
Standard HD-SDI allows for a single 4:2:2 image to be carried on one cable at 1.485 Gb/s. The image uses the Y Cb Cr colorspace
and uses a bit depth of 1 0 bit per color component.
Due to the data rate limitations only 23.976, 24, 25, 29.970 and 3 0 fps streams are achievable.
Dual-Link HD-SDI signal
Dual Link
1.5Gb/s
1.5Gb/s
1080p 50/60
2
or
1080p 4:4:4
Dual-Link HD-SDI is m ainly two standard HD-SD I signals carrying a single image stream split between the two cables. The main
advantage is that color subsampling is no longer required, and the image can be transmitted in 4:4:4 quality, which then also allows
the RGB (or XYZ ) color space to be us ed.
The main link will contain a standard HD-SDI signal, the sec ond (enhancement) link contains the m issing Cb and Cr s amples.
Depending on the implementation the enhancement link could also contain extra information to increase the bit depth.
3G HD-SD I signal
3G
3Gb/s
1080p 50/60 (Level A)
or
1080p 4:4:4 (Level B)
3G HD-SDI uses a higher data rate (2.97 Gb/s). This allows a single cable interface to a chieve the same c apabilities of a Dual-Link
HD-SDI implementation.
In direct mapping (level A) this is used to achieve higher frame rates. (50, 59.940 and 60 fps streams are supported).
2. Not supported in Alchemy
100 R5906753 DPXK BLP SERIES 20/11/2017
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