FAQ

Could not load the Qt platform plugin “xcb”

If you get this error:

qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.

Then you are not running valkka-live directly in a desktop, but from remote etc. connection (or in docker, etc. “headless” environment).

It has really nothing to do with libValkka or valkka-live. In fact, none of your Qt and KDE-based desktop programs would work at all. Check with this command:

echo $XDG_SESSION_TYPE

and make sure that it reports the value x11.

If the error persists, you’re desktop environment might have missing or broken Qt/KDE dependencies. Install the whole KDE and Qt stack with:

sudo apt-get install kate

(this pulls a minimal KDE + Qt installation as dependencies of the Kate editor)

If this error still persists and is reported by python’s cv2 module, you have a broken cv2 version, so uninstall cv2 with:

pip3 uninstall opencv-python
sudo pip3 uninstall opencv-python # just in case!

That name of that sneaky broken opencv python package might also be “opencv-python-headless-something”. You can see the versions installed with pip freeze | grep -i "opencv"

And install your linux distro’s default opencv instead with:

sudo apt-get install python3-opencv

Discarding late frame

One of the typical error messages you might find in the terminal, please read about them from here

2K and 4K cameras

I have benchmarked Valkka against an expensive commercial program. The other program is capable of showing 20 live 2K cameras on the screen using a cheap laptop.

That commercial program is not streaming at 2K resolution. Instead, it requests the so-called “substream” from those cameras which is typically 720p or less.

If you want to benchmark against Valkka, you must use the substream address instead.

The substream address depends on the manufacturer. For HIK, mainstream and substream addresses are typically (might vary, depending on the camera model):

main stream : rtsp://user:password@ip_address
sub stream  : rtsp://user:password@ip_address/Streaming/Channels/102

in Valkka Live camera config menu, you should then use Streaming/Channels/102 at the Tail field