Cael
Posts: 96
Joined: Sat Jul 07, 2012 7:08 am

Using 2 Displays with the Pi4

Sun Aug 11, 2019 3:55 am

Now from what i gather, you can use both HDMI outputs just not at 4k. But, can you use HDMI & the Composite out at the same time?

i display atm to the HDMI port closest to the USB-C power connector at 800x480 (older Waveshare 7'' HDMI Screen) and if i wanted to say capture output from the pi from my Elgato, i unfortunately would either haveto change to 640x480 or 1024x768 or higher which neither is supported by the screen. and im a tad strapped atm to get the newer Waveshare screen that does a higher more supported resolution by the original Elgato HD Capture (i keep my 1st gen one for the Analog capture capability.. and its why im inquiring if its possible to use HDMI and Composite at the same time)

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rpdom
Posts: 17033
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Using 2 Displays with the Pi4

Sun Aug 11, 2019 5:46 am

Cael wrote:
Sun Aug 11, 2019 3:55 am
Now from what i gather, you can use both HDMI outputs just not at 4k.
You can use both at 4K, but only at 30Hz. You can only use one of them if refresh rate is 60Hz.
But, can you use HDMI & the Composite out at the same time?
No. The HDMI and Composite use a common part of the Videocore. Only one of them can use it at a time.

I don't know if it is possible to mirror the output to both HDMIs when they are running at different resolutions. If it is possible, that may work for you.
Unreadable squiggle

Cael
Posts: 96
Joined: Sat Jul 07, 2012 7:08 am

Re: Using 2 Displays with the Pi4

Sun Aug 11, 2019 6:06 pm

rpdom wrote:
Sun Aug 11, 2019 5:46 am
Cael wrote:
Sun Aug 11, 2019 3:55 am
Now from what i gather, you can use both HDMI outputs just not at 4k.
You can use both at 4K, but only at 30Hz. You can only use one of them if refresh rate is 60Hz.
But, can you use HDMI & the Composite out at the same time?
No. The HDMI and Composite use a common part of the Videocore. Only one of them can use it at a time.

I don't know if it is possible to mirror the output to both HDMIs when they are running at different resolutions. If it is possible, that may work for you.
thanks, figured the trend stayed pretty much the same since the beginning. MicroHDMI adapters are cheap anyway :3

aBUGSworstnightmare
Posts: 1890
Joined: Tue Jun 30, 2015 1:35 pm

Re: Using 2 Displays with the Pi4

Mon Aug 12, 2019 4:31 am

Don't know if it is really working that way, but:
Open screen configuration tool
Put your two desktops on top of each other
Click the button with the green check mark

Your screen should show the same content. Be warned that the taskbar may be incompletely display on the lower resolutiin screen

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