LED controller and LED walls work hand in hand. For a satisfying display of one’s own content on the LED wall it is therefore necessary to have basic knowledge of the calculation method of the controller. In a first article on the performance of a network cable you can read why the output of an LED controller and with that a network cable usually controls 650,000 pixel (px) of an LED wall. In the following we want to further talk about the features of the input, which influences the pixel capacity of a controller significantly.

Meaning of the input

From the calculation explained in the first article, it would follow that a controller with, for example, 4 outputs would have a total of 4 x 650,000 = 2,600,000 px capacity (1 pixel = 1 LED). In fact, however, this effectively results in 2,300,000 px, because in addition to the capacity of the output source, the capacity of the input source must also be taken into account in the calculation process. This is because the video input – just like the input source – has a certain bandwidth. It also applies here: the higher the frequency, the fewer pixels can be processed.

Please note: not the data cable is limiting, but always the input at the controller.

Here, the difference is of significance: is the controller in use only a sending card or is it an All-in-One device with a scaling function? The MCTRL660 e.g. runs as a sending-only card with 4 LED OUT Ports theoretically 2,600,000 pixels, practically, however, only 2,300,000 px. In contrary, the All-in-One device VX4S-N manages at the same number of outputs also practically the full capacity of 2,600,000 px, as it has a video processor with its integrated scaling function connected before it, it is able to upscale the content. It behaves in the same ratio between MCTRL4K and UHD Jr. With the same number of LED OUT Ports (16) the sending card MCTRL4K runs 8,800,000 px and the All-in-One controller UHD Jr effectively 10,400,000 px.

The theoretical possibility of e.g. the MCTRL660 to control 2,600,000 is thereby hindered because there is practically no input source available that would be able to do so.

UHD Jr Rückseite

NovaPro UHD back view, source: NovaStar Shop


LED controllers have typical versions of HDMI inputs. Take, for example, the version HDMI 1.3, which transfers 1920 x 1200px @ 60 Hz. Depending on the version of the HDMI connection, a certain capacity of input is given, a controller cannot operate more. So there is a practical limitation via the HDMI input.

Here, the frequency in which the contents are played shall be mentioned again. When operating at 60 Hz the content runs quicker, but more capacity is needed as well. When lowering the frequency to 30 Hz the system would run slower but could transfer a higher resolution.

This is easily noticeable at the example of the VX1000. The All-in-One controller is a 4K1K device, should one want to use it for a 4K2K application, it helps to lower the frequency to 30 Hz.

To come back to the formerly mentioned comparison between the All-in-One controller VX4S-N and the sending card MCTRL660, the according HDMI inputs should be mentioned. Both controllers run with a HDMI input 1.3 (1920 x 1200px @ 60 Hz). The controllers can only manage the input within this limit. Here a sending-only card, as mentioned, can transfer pixel to pixel in a 1-to-1 ratio, while the controller with the scaling function has the opportunity to upscale.

Please note: interpolating a disadvantage: Since no own input is added, the result of upscaling is only a multiplication whose quality is somewhat worse.

All indications are always flexible and depend on one’s personal use. It is important to understand that the connection options are not lost. With the MCTRL660 with 6 inputs one can for example effectively use 2.3 million of 3.9 million pixels with the primary connection. Hence, pixel capacity always remains that can for example be used to duplicate the screen or for a backup circuit.

Do you have further questions regarding pixel, controller and network cable? Then give us a call at +49 551 492 493 44 or send an email to vertrieb@ledtek.de.