Change the Resolution of Anthias

Hello Forum,

We have been using Screenly (or now Anthias) for years and are actually quite happy with it.
We use it to display PRTG maps of our internal environment. This means that websites are called up and rendered on the fly.
So far, everything has been running on a Raspberry Pi 3, but for performance reasons we have switched to a Pi 4B.
Our current version is the master@7b559ef based on Debian Bookworm.
The setup and restoration of the backup went smoothly. Everything also ran smoothly on my Full HD monitor, but for some reason I only see a white screen when I connect the Pi4 to a 4K monitor. Videos and pictures are no problem.
By the way, it always starts fresh with the monitor connected.

I have already searched the forum in this regard, but unfortunately I have not found a solution that fits our problem.

Is there a way to change the resolution to Full-HD?
It doesn’t sound like a complex problem at first, but it does seem to be one.
None of the 3 methods I found online worked.
Raspi-config doesn’t work because the option for the resolution is simply missing.
xrandr doesn’t exist because I’m using the Lite version of Raspi-OS and when I install it manually it says “can’t open display”.
I had tried to tamper with the /boot/firmware/config.txt. and insert things like
hdmi_group = 1
hdmi_mode = 16
or framebuffer_width etc.
but it still switched back to 4K…

Does anyone have any idea how I can get back to full HD?
That would also be the most practical solution, as we wouldn’t have to recreate the few dozen images that are all in full HD.

Kind regards


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I had the same problem few months ago.
You can find here the solution salmanfarisvp gave me :
Anthias on 4K screen - Anthias - Anthias Forum (

It works perfectly for me. :slight_smile:


many thanks for the tip.
I’ve actually already seen the post, but I was kind of against using an outdated version of Raspi-OS, because I was afraid that some update might break it again.

I have actually found another solution to the problem that works for me.
You can find it here:
RPI4 issues with 4k display
I have adapted this solution to the latest version by adding
"`shm_size: ‘1gb’ " in “/home/pi/screenly/docker-compose.yml” at the new corresponding position. It then looked like this:
Another restart and it worked.

Such a complicated solution would not be necessary if there was a simple way to change the output resolution.
Which brings me back to my question above…

Thanks again for the answer, but that’s why I’ll leave the thread open.

@APeters, I recently merged this PR (#1894) that fixes assets playback in 4K displays.

  • What the PR does is increase the shared memory size of the anthias-viewer container.
  • To pull the new changes, run:
# Make sure that you're inside the project root directory.
cd ~/screenly

# Pull the latest changes from the `master` branch.
git pull 

# If you can't pull the changes, you can just add a `shm_size` in the `anthias-viewer` service of `docker-compose.yml.tmpl`.
# You can set it to anything larger than `64mb` (which is the default value.) like `256mb`, `1gb`, etc.

# Restart the docker containers, but you have to do it in a specific way, since `docker-compose.yml` is auto-generated based on the template file `docker-compose.yml.tmpl`.
docker compose down && ./bin/
  • Regarding your concern of having a simpler way of changing the output solution, the simplest that it can get is to add settings via the web UI where output resolution can be tweaked.

@nicomiguelino, thanks.

What do you mean by “add settings via the web UI”?
I can’t see any point where this might be possible.
Under system info there are just… infos.

And at the settings tab there is nothing regarding any Display settings.

Can you please explain this further?

@APeters, As of now, there are no support for changing the resolution easily, for instance, in web UI.

What I meant is that input boxes for specifying the resolution can be added in the settings page in the future.

Ah, that’s what you meant. Yes, that would be great.

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@APeters I created a PR for that (for reference): Web UI support for changing output resolution · Issue #1895 · Screenly/Anthias · GitHub