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What is HDMI 2.0 4K@60Hz 4:4:4

What is HDMI 2.0 4K@60Hz 4:4:4 ?


We talking about the HDMI 4:4:4 every day, do you know why we need 4:4:4, what is the difference between 4:2:0.


The human eye is more sensitive to black and white detail than color detail. Chroma subsampling compression takes advantage of this fact by sending a full-resolution black and white (luma) information and only partial-resolution color (chroma) information. The result is a reduction of image data with no accompanying visual degradation.


There are three main types of chroma subsampling for video content: 4:4:4; 4:2:2; and 4:2:0. With 4:4:4 there is no subsampling. With 4:2:2, half of the color detail is thrown away. And with 4:2:0, 75% of color information is discarded. Blu-ray, HDTV, and DVD all use 4:2:0 subsampling. We don’t notice the loss of color detail right now with those formats, and we aren’t likely to notice it after the move to UHD.


Below is a visual diagram of chroma subsampling from Wikipedia that helps to explain how it works.

HDMI 2.0 4K@60Hz 4:4:4 Chroma-Subsampling-Example.png


Chroma Subsampling Example


One unheralded change that HDMI 2.0 brings is an ability to send 4:2:0 content natively.  Previous HDMI versions only used 4:2:2 or 4:4:4 subsampling, even though the Blu-ray format uses 4:2:0, so content first needed to be converted to 4:2:2 or 4:4:4. With UltraHD pushing the bandwidth limits of HDMI, Version 2.0’s ability to send bandwidth-saving native 4:2:0 content, and to do so without degrading image quality, is a benefit.


By applying 4:2:2 subsampling to our prior high bit-depth content example—a UHD image at 60 fps with full 36-bit color depth and 32 audio channels—we now only need 12.02 Gb/sec of bandwidth. Using 4:2:0 drops that requirement to 9.03 Gb/sec. The signal can easily fit into HDMI 2.0 with bandwidth to spare.


Use of 4:2:0 subsampling also means that HDMI 2.0 offers enough bandwidth for an 8K-resolution (7680×4320) UHD image at 24 fps with 36-bit color and 32 audio channels.  Hollywood films generally aren’t shot at this resolution, and displays that can handle it don’t yet exist, but the capability is there.


Here’s a table showing possible UHD resolutions, bit-depths, chroma subsamplings and refresh rates. All listings include 32 channels of 24-bit, 96 kHz lossless audio except for Blu-ray, which is limited to 8 channels.

HDMI 2.0 4K@60Hz 4:4:4 HDMI-Calculator-Base-10.png


HDMI Calculator Base 10


There are a couple of other Rec. 2020 features such as 120 fps content that HDMI 2.0 does not have the bandwidth for. Such content, and displays designed to handle it, might be a few years off, but it looks as if HDMI will need another revision at some point to accommodate 120 fps.


Smartavlink keep focus on 4K@60Hz 4:4:4,provide kinds of HDMI 2.device, such as HDMI 2.0 Repeater HDMI2.0 Extender, and HDMI 2.0 Active Optical Fiber Cable, all these support 4K@60Hz 4:4:4


The future, is HDMI 2.0 4:4:4 world !