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When 4K TV was first launched a few years ago, there were overwhelming advertisements, but the actual experience was not very good. On the one hand, 4K TVs were mixed, and there were many fusses about panels, signal formats, and processing chips; On the one hand, 4K film sources are relatively scarce, and 4K TVs have become decorations. But this is not the case for the led wall screen display indoor display industry. 4K can be said to be the best solution for ultra-clear small-pitch LED displays.

Challenges of small pitch high-end applications

As the technology continues to mature, small-pitch LED displays are becoming more and more popular in high-end display applications due to their own advantages. High-end applications have higher and higher requirements for display effects. For example, some require the best display effect, and must customize the material and point-to-point display, that is, the video material must be customized corresponding to the physical resolution of the LED display, and the video signal processing will not be scaled. , point-to-point display, such a single 1080p full HD interface can no longer meet the needs of small-pitch ultra-high-resolution display screens.

Traditional non-4K solutions are complicated to operate

Before the introduction of 4K processors, the common practice in the industry was to use multiple DVI output graphics cards to expand and splicing. As shown below:



One difficulty of this solution is that the operation is relatively complicated, and sometimes it is necessary to perform fusion processing on the patchwork, which requires a professional graphics card with fusion function. Another difficulty is the synchronization problem, whether it is AMD, NVDIA flagship graphics card or a fusion It is also difficult for multiple DVI output ports to be fully synchronized, so that tearing will occur at the splicing position.



Fast motion out of sync: tearing

Therefore, LVP86XX and other multi-window synchronous splicers need to be used. The specific wiring diagram is as shown in the figure below. The related fusion band calculation and synchronization settings are relatively complicated and require professionals to operate.



4K processor solution is easy to operate

Using a 4K processor device, only one HDMI or DP interface is needed to achieve the display effect that can only be achieved by 4 DVI output expansion splicing. The playback operation on the PC side becomes very simple, and for large-screen systems, the 4K processor LVP609 of Viovision converts 4K signals into multiple 1920x1080 resolution DVI outputs, and the multiple output ports are fully synchronized. It only needs to use ordinary sending cards to load together, and finally through the fast splicing function of LVP609, simply input a few parameters and the splicing can be completed automatically. In this way, there is no need to use a 4K sending card that is expensive and does not have scaling processing. At the same time, the rich video signal interface that comes with the processor also provides convenience for connecting to different devices.



LVP609 4K point-to-point display solution



Differences in the 4K signal itself

Regarding true and false 4K, it has been hyped for a while in the field of 4K TV. 4K refers to the resolution of 3840x2160 or 4096x2160. A signal whose width cannot reach 3840 cannot be called 4K, and a signal whose height cannot reach 2160 cannot be called 4K. The same 4K signal also has different differences, such as whether the frame frequency is 30Hz or 60Hz, whether the color space is YUV or RGB, etc. These bring obvious differences in image quality to LED displays with very good display effects.

The maximum frame rate of the HDMI 1.4 standard is 30Hz, that is, 30 frames of images are transmitted per second, while the maximum parameter of HDMI 2.0 is 60Hz, that is, 60 frames of images are transmitted per second. The parameters of 60 frames are twice as high as those of 30 frames, and the image quality and details are better. The higher the number of frames, the smoother the picture, which is best reflected in the intuitive experience. The higher the value, the closer the picture is to the real world observed by human eyes.

Color space is also a very important parameter. The most widely used formats are RGB and YUV. YUV has different sampling formats such as 4:4:4, 4:2:2, 4:1:1 and 4:2:0. Among them, RGB and YUV 4:4:4 have richer information and better colors, but require very high storage space and transmission bandwidth. Several other methods compress colors in order to save bandwidth and storage space.

The difficulty of 4K 60Hz processing lies in the large amount of data and high bandwidth. The point frequency of ordinary 1920x1080 60Hz is 148MHz, while the point frequency of 4K 60Hz is 594MHz, which requires high signal transmission and processing. For the LED display, it is also required that the signal transmission and processing cannot be dropped, and each DVI output port must be completely synchronized. Therefore, up to now, LVP609 is still the only 4K 60Hz LED video processor in China that truly supports RGB\YUV 4:4:4 input format.