I need to display a video on two screens with VLC by command, in a non-manual way.

The two screens are each connected by a HDMI cable. The video files have the 3840 * 1080 resolution so they could be split into two 1920 * 1080 videos while playing. This is so that the two screens are synchronized properly.

If I use the following intended “video wall” feature of VLC, the video is splitted into two parts as intended, however they open above one another on one screen:

cvlc --fullscreen --video-splitter wall --wall-cols 2 --wall-rows 1 vid.mp4

I am aware that there are inputs like --qt-fullscreen-screennumber=0, however here I can’t specify this for the each given split. --directx-device=DISPLAY<#> is not usable for me as I use this on a Raspberry PI wih Linux. The --wall-active input also had no effect.

What am I doing wrong? How can I automatically open the two video splits on each screen in fullscreen?