[ale] Raspian Screen Duplicating - How Hard Can It Be?
neal at mnopltd.com
neal at mnopltd.com
Mon Jan 1 20:18:59 EST 2024
Thanks for the reply. Fair enough on resolution. Frankly, VGA
resolution would be fine. We're putting up big words.
I plugged in the 2nd monitor again after dinner, and the xrandr
--current now reports the 2nd HDMI as XWAYLAND2, not XWAYLAND1.
I tried your suggestion regarding using the Screen Layout Editor, and
indeed one can position the 2nd HDMI on top of the 1st. Then what
happens is IF you move a window on the first screen, it shows up on
both. UNTIL you let go of the mouse button, when it disappears.
I did get the xrandr --output XWAYLAND2 --same-as XWAYLAND0 to run to
completion with out errors, and got the same behavior.
Rebooted, and the 2nd HDMI was back to XWAYLAND1.
neal at raspberrypi:~ $ xrandr --output XWAYLAND1 --same-as XWAYLAND0
X Error of failed request: BadMatch (invalid parameter attributes)
Major opcode of failed request: 139 (RANDR)
Minor opcode of failed request: 7 (RRSetScreenSize)
Serial number of failed request: 29
Current serial number in output stream: 30
This says to me that the syntax was ok, and it passed the initial edits,
and tried to make that action.
As you note, these are nearly identical displays. The only difference
I spot is 0 has 510mm, and 1 has 520mm.
I did find some pretty dense discussion of mirroring displays of
different resolution:
https://www.baeldung.com/linux/mirror-monitors-different-resolutions
but it's waaaaaaay to late in the day to try and parse that, especially
with light grey print on white.
As you note, a splitter might be less of a headache than this, which i
sure thought would be simple.
On 2024-01-01 16:25, Alex Carver via Ale wrote:
> Answering in reverse, if your projector and TV will have different
> resolutions then nothing is going to save you short of just making the
> Pi display at the lowest resolution of the two devices.
>
> Simplest solution is an actual HDMI splitter and then you don't have to
> think about it.
>
> But you can run this to get the current displays:
> xrandr --current
>
> Some posts suggest you can use the graphical screen setup tool (Screen
> Layout Editor) to overlap the monitors which will result in sharing
> content. Drag one monitor over the top of the other.
>
> On 2024-01-01 12:48, Neal Rhodes via Ale wrote:
>
>> Trying to stay retired, but a fella can't never get totally away from
>> the sea....
>>
>> Needing to setup a PI 4B to simply display words for an Irish Pub
>> Night to both the onboard HDMI outputs. One will go to a projector;
>> the other to a 40" TV. Both HDMI. Both need to stay in Sync.
>>
>> I'm testing it now on a pair of 1920x1080 HDMI monitors. Both work
>> fine as independent monitors.
>>
>> My notes on how to do this came from Bing AI, courtesy of Raspian
>> Forums, and seemed pretty simple:
>>
>> Y_es, you can make both HDMI outputs on a Raspberry Pi 4 have the same
>> output on Raspbian. Here are the steps:_
>> _ _
>> _Use the xrandr command to mirror the displays1. Replace <projector>
>> and <desktop> with your display names:_
>> _xrandr --output <projector> --same-as <desktop>_
>> _In the example provided in the forum, <projector> was HDMI-2, and
>> <desktop> was HDMI-11._
>> _To check the display names, run the following command when both
>> displays are attached1:_
>> _xrandr --current_
>> _ _
>> _Please note that these steps should work by default on Raspberry Pi
>> OS, Bullseye2. If you encounter any issues, please let me know! I'm
>> here to help._
>>
>> Alas, it ain't working.
>>
>> eal at raspberrypi:~ $ xrandr
>> Screen 0: minimum 16 x 16, current 3840 x 1080, maximum 32767 x 32767
>> XWAYLAND0 connected 1920x1080+0+0 (normal left inverted right x axis y
>> axis) 510mm x 290mm
>> 1920x1080 59.96*+
>> 1440x1080 59.99
>> 1400x1050 59.98
>> 1280x1024 59.89
>> 1280x960 59.94
>> 1152x864 59.96
>> 1024x768 59.92
>> 800x600 59.86
>> 640x480 59.38
>> 320x240 59.52
>> 1680x1050 59.95
>> 1440x900 59.89
>> 1280x800 59.81
>> 720x480 59.71
>> 640x400 59.95
>> 320x200 58.96
>> 1600x900 59.95
>> 1368x768 59.88
>> 1280x720 59.86
>> 1024x576 59.90
>> 864x486 59.92
>> 720x400 59.55
>> 640x350 59.77
>> XWAYLAND1 connected 1920x1080+1920+0 (normal left inverted right x
>> axis y axis) 520mm x 290mm
>> 1920x1080 59.96*+
>> 1440x1080 59.99
>> 1400x1050 59.98
>> 1280x1024 59.89
>> 1280x960 59.94
>> 1152x864 59.96
>> 1024x768 59.92
>> 800x600 59.86
>> 640x480 59.38
>> 320x240 59.52
>> 1680x1050 59.95
>> 1440x900 59.89
>> 1280x800 59.81
>> 720x480 59.71
>> 640x400 59.95
>> 320x200 58.96
>> 1600x900 59.95
>> 1368x768 59.88
>> 1280x720 59.86
>> 1024x576 59.90
>> 864x486 59.92
>> 720x400 59.55
>> 640x350 59.77
>> neal at raspberrypi:~ $ xrandr --listmonitors
>> Monitors: 2
>> 0: +XWAYLAND0 1920/510x1080/290+0+0 XWAYLAND0
>> 1: +XWAYLAND1 1920/520x1080/290+1920+0 XWAYLAND1
>> neal at raspberrypi:~ $ xrandr --output 1 --same-as 0
>> warning: output 1 not found; ignoring
>> neal at raspberrypi:~ $ Xrandr
>> bash: Xrandr: command not found
>> neal at raspberrypi:~ $ xrandr --output XWAYLAND1 --same-as XWAYLAND0
>> X Error of failed request: BadMatch (invalid parameter attributes)
>> Major opcode of failed request: 139 (RANDR)
>> Minor opcode of failed request: 7 (RRSetScreenSize)
>> Serial number of failed request: 29
>> Current serial number in output stream: 30
>> neal at raspberrypi:~ $ xrandr --output +XWAYLAND1 --same-as +XWAYLAND0
>> warning: output +XWAYLAND1 not found; ignoring
>>
>> The Screen Layout Editor shows displays as HDMI-A-1 and HDMI-A-2, so I
>> also tried...
>>
>> neal at raspberrypi:~ $ xrandr --output HDMI-A-2 --same-as HDMI-A-1
>> warning: output HDMI-A-2 not found; ignoring
>> neal at raspberrypi:~ $ xrandr --output HDMI-2 --same-as HDMI-1
>> warning: output HDMI-2 not found; ignoring
>>
>> I don't see an option in xrandr to simply tell me what outputs it
>> thinks it has.
>>
>> And, is there a better way of doing this? Also considering that the
>> real use will involve beer, and the projector may have different
>> resolution from the TV?
>>
>> regards,
>>
>> Neal
>>
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