4K development
in broadcasting system
1. The origin of 4K
The earliest concept of 4K originated from the TV industry. When the film industry began to abandon film movie, Entering digitalization was first reflected in the post-production stage of the film-the birth of Digital Intermediaie.
It
first uses a film scanner to scan film negatives taken by a 35mm camera into
digital image files. In the process of converting films into digital images, in
order to fully restore the film shooting effect, an image with a resolution of
4096 × 3112 pixels is used. Because its horizontal resolution is 4096 pixels,
it is referred to as 4K. Later the 4K concept was promoted and introduced into
the TV industry, and was quickly accepted by Japanese TV manufacturers, but the
standard details were slightly different. Among the released 4K TV prototypes,
only a small part adopts a resolution of 4096 × 2160 like the film industry,
and more TVs adopt a resolution of 3840 × 2160 with a 16: 9 widescreen picture.
2. Broadcast Standard of 4K
UHDTV，Ultra High Definition Television is
also called as Ultra HDTV. 4320P and UHDV is the next generation technology
of HDTV including 4K resolution (3840X2160) and 8K resolution (7680X4320)
Baseband image format:
ITU-RBT.2020 (August 2012), SMPTE2036
Aspect ratio: 16: 9 (same as HDTV)
Resolution: 3840x2160 pixels (4K or QFHD), 7680x4230 pixels (8K)
Frame rate: 24/25/30/50/60/120 frames per second, progressive scanning
Gamma / color gamut: TV gamma 2.2 / ITU-R BT.2020 color gamut
Quantization: 10/12 bits
Interface method:
Four 1.5G HD-SDI interfaces can transmit one 4: 2: 2 @ 30P (highest) 4K band base signal
Four 3G-SDI can transmit one 60P (highest) 4K signal
One 12G-SDI interface (coaxial cable or fiber) can transmit one 4K@60Hz signal
The SMPTE ST-2082 12G-SDI interface has been released in 2015, now more and more 12G-SDI devices has been released like 12G-SDI camera, 12G-SDI fiber optic extender, 12G-SDI encoder, decoder and so on.
HDMI1.4 interface can transmit 4K display signals (up to 30P, there are products already)
HDMI2.0
interface can transmit 4K signals (up to 60P, no products for the time being)
3. Choice of 4K broadcast encoding method
H.265 encoding can provide videos with the same definition at half the code rate than H.264 encoding, which can save a lot of storage space and video transmission bandwidth, and also can provide higher encoding efficiency. The efficiency is much higher than Mpeg2, so H.265 (HEVC) encoding is used for 4K broadcasting, which is the best and reasonable choice.
In addition, the current mainstream set-top box 4K decoding chips support H.265 (HEVC) encoding, and its application will not be restricted