维奥

1. Introduction

For super-high-resolution LED displays, we often use video scalers (such as LVP605) or splicers (such as LVP40X, LVP8601) for splicing. This article is to help users to eliminate the splicing gap.

2.Cause of splicing gap

We have introduced how to calculate the splicing parameters in last article, but in actual application, the DVI input and output may encounters phase clock sampling difference, which will cause image gap at the edge of unit screen. Turns out to be misalignment, black line,as shown in the following pictures.

Fractures (black or bright lines appear in the splicing edge)

Image content missing caused by misalignment

Image edge repetition

3. Solutions

For ease of understanding, we illustrate with an actual case.。

As shown in the figure below, the solution is to use LVP404 with 2 DVI output splicing. LED total resolution is 3584*1056 , unit screen resolution is equally 1792x1056.

The two output port parameters of LVP404 are set as follows:

Incomplete image display is showed as following picture:

Two steps to solving the problem:

①Remove image fracture

First identify the black line(or bright line) is on left side or right side of LED screen.

If the bright line or black line is on right side of screen, set OUT2 H_start to a negative number (such as -2), remove the image to left by 2 pixel line. This operation may cause black line on right edge, to eliminate the line, increase the output width from 1792 to 1794.

If the bright line is on left unit screen, increase the output width of OUT1 (for example, set it to 1794), scale up the image to cover the black line(or bright line).

The effect after optimization is as follows

② Solve image misalignment

Except black line, we may also encounter image missing at the splicing edge. To solve this problem, we can fine-tune the input image parameters by increasing input width, so the missed image content will appear on screen. Details as follows:

We gradually reduce H_start of Out 2, the missed image content will show up accordingly.

If we adjust the H_Start too much, there will be image repeat on screen, as showed in the figure below. At this point, we can appropriately increase the output width of the OUT1 port, remove the duplicated part, achieve complete image display.

In the actual application, the Horizon start of OUT1 and OUT2 is not a fixed number, we need to calibrate two parameters slowly, so as to realize whole image display without image fracture or black line.

The above is the method for solving image misalignment. If you encounter image missing or repeat, please refer to the second procedure.

Additional instructions:

In actual debugging, we found that use the slash line to identify the splicing misalignment is more efficient.