Hi
I hooked up 2 4k displays to the pi4 and i cant get both of them on 4k (non-mirrored). The first one goes to 4k 30hz just fine but the 2nd one always stays at FHD 60hz. Tried wiring up thing different as well but the results are the same. The displays are identical models.
Any ideas how to solve this?
Is there a way to forcefully set the resolution for each HDMI port separately?
You might use custom configuration settings. Device page > Edit configuration > Advanced/Development > Custom Pi boot configuration. Setting 2x 30Hz should work like this (see also description of those values):
hdmi_group:0=1
hdmi_mode:0=95
hdmi_group:1=1
hdmi_mode:1=95
I’m not entirely sure if that full combined resolution is really that useful as things get laggy at some point. What type of content do you intend to show?
Most of the time images made by artists. (its for a art gallery)
However it is highly likely there will be some videos as well. In that case i plan to use 2x pi4’s connected to 4x 4k displays (2+2 just to get a bigger size on the wall). It is highly unlikely anyone will ever submit a 8k video file, but incase they do i want to try out different ways to make it happen.
So far the biggest on upcoming schedule is 4k videos and the pi4 handles that just fine once i re-encode the video with handbrake.
But ye for images… a crisp image is what i am trying to achieve. To take full advantage of the displays.
Many thanks. I will try out this solution once the displays are available.
Just a warning: 8K isn’t going to happen on the Pi. It cannot decode that. And 4K is already taxing and it’s not possible to play two of those at the same time. Your “non-mirrored” setup implies that this is something you might want to do. For such high resolution installations with two displays, maybe the Pi isn’t the best choice.
For 8k videos i figured the as much. I will get a dedicated machine for that when it comes to it. Or use 4x pi4s if available and chop up the video. If its even possible to get them in sync on essentially 4 separate video files.
As for 4k videos … i will probably end up running those displays at 1080p and splitting the video horizontally in half for a 2x pi4 4x display config. The result should be indistinguishable.
As for images … the pi4 should be capable enough to show 7680x2160 images on 2x 4k displays. At least thats my understanding. If i’m wrong in that please let me know.
I’d like to add that infobeamer has saved me a ton of leg work and the pricing model is perfect for the usecase we have. Thank you for making this.
In theory yes, but two problems:
There isn’t a package that supports both playing two videos on two attached displays in addition to also being able to synchronize playback across multiple devices. The scheduled player can play two videos at the same time and does support placement like that, but doesn’t do synced playback. And the video wall packages support syncing across devices, but not multiple videos per device.
The Pi4 isn’t really good at perfectly synced playback. Both across devices and even if two displays are attached to one Pi: It doesn’t support adjusting the HDMI clock so flipping to the next frame of a video can happen at with a minor time offset between both screens or when multiple Pis try synced playback. The Pi3 supports adjusting the clock like that, but obviously doesn’t support multiple displays.
Image:
Right now the maximum size supported for imported images is 4096x4096. This is due to the way textures are rendered on the display (using OpenGL) and the maximum size limitations imposed by that method. In theory this could be worked around by using multiple textures per image, but that’s not implemented. As the most common use case is a single 4K or two FullHD display, this isn’t usually an issue, but 2x4K obviously is more than that.
Now that I think about it, I’m not even sure the info-beamer process running on the Pi would allow you to create a 7680x2160 rendering area at all, given the 4096x4096 limitation of textures. I don’t think I’ve ever tested that.
Again, not using the Pi and instead using a quad HDMI/display port graphics card and dedicated PC might be simpler for a one-time installation with such requirements.