What is the rational ( or what are the advantages ) of having a double HDMI port on the Raspberri Pi 4.

Since the Pi is new, I did not find any info around and still did not tested myself- but What can you do with that kind of configuration that can not be done with 1 HDMi and a simple splitter cable? As far as I understand, the splitting is anyhow on the software level as higher resolution.

Also - does anyone knows if the ports / drivers support CEC out of the box ?

After comments :

My terminology was wrong, by "a simple splitter cable" I meant MST supported one.

  • 1
    The rationale is that the SOC can do it and it has many real-world applications. A splitter merely gives you a duplicate screen. Dual HDMI gives you the option to expand / extend the desktop. E.g. code editor on one screen and program output on another; presentations with screen and projector, digital signage, etc, etc...
    – Dirk
    Jun 28, 2019 at 15:50
  • Using a splitter will only let you output to one display at a time and switch between the two displays connected. Or some may let you view the one output on two monitors at the same time. By having two outputs you will have two desktops you can attach and use. I.E. connect display one and run an application there and connect display and have a second application on that screen (as a basic setup, you can obviously put whatever you want on either display)
    – rohtua
    Jun 28, 2019 at 17:26
  • @rohtua , @Dirk - wouldn't the software desktop that can be expanded to horizonta lx2 and then move the windows would be the same ? I am really asking in order to understand what can be done with this configuration. I have been using a splitter and a custom resolution on the pi before and I just really want to understand what can be done more ... Jun 29, 2019 at 3:05
  • Can you give an example of what you mean by a "splitter" multiple desktops rely on software to run but it also depends on the hardware being powerful enough to drive multiple displays and having 2 outputs to output 2 displays. A splitter takes one input which can be output on 2 displays or switched from 1 display to another. It can't run two different outputs from 1 device only mirror 1 output. If you want 2 separate monitors with different programs running on each monitor you need 2 outputs superuser.com/questions/805983/…
    – rohtua
    Jun 30, 2019 at 7:31
  • @rohtua - you are right about the fact that maybe my terminology was wrong. by splitter I meant MST supported cable / device. My point of the question was - the PI ( at least to my understanding ) was / should be a very minimal config to be extended by external devices if needed. ( hence hats, extension cards, screens etc. - or splitters ). I mean - there must be 10,000 things that can be added to the pi and will still be usefull :-) Jul 1, 2019 at 4:10

1 Answer 1


The Raspberry Pi is used in a lot of digital signage applications. Double HDMI outputs differentiate the Pi in that market. Think of digital signs in airports, two screens mounted back-to-back. They can now show diffrerent content.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.