2. ICMP functionality
2.6 ICMP SDI spe cifications
3G-SDI
Serial Digital Interface (SDI) is a serial link standardized by ITU-R BT.656 and the Society of
Motion Picture and Television Engineers (SMPTE). SDI transmits uncompressed digital video
over 75-ohm coaxial cable within studios, and is seen on most professional video infrastruc-
ture equipment. The first revision of the standard, SMPTE 259M, was defined to carry digital
representation of analog video such as NTSC and PAL over a serial interface and is more pop-
ularly known as standard-definition (SD) SDI. 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 inter-
face is commonly called the HD SDI interface and is defined by SMPTE 292M, using the same
75-ohm coaxial cable. Studios and other video production facilities have invested heavily on
the hardware infrastructure for coaxial cable and have a vested interest in extending the life of
their infrastructure. Fortunately, SMPTE recently ratified a new standard called SMPTE 424M
that doubles the SDI data rates to 2.97 Gbps using the same 75-ohm coaxial cable. This new
standard, also called 3-Gbps (3G)-SDI, enables higher resolution of picture quality required for
1080p and digital cinema.
SDI terminology
Standard HD-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 10 bit per color component.
Due to the data rate limitations only 23.976, 24, 25, 29.970 and 30 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 mainly two standard HD-SDI 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 used.
The main link will contain a standard HD-SDI signal, the second (enhancement) link contains the missing
Cb and Cr samples.
Depending on the implementation the enhancement link could also contain extra information to increase
the bit depth.
2. Not supported in Alchemy
16 R5905722 ICMP 09/11/2016
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