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Description
In the situations described below, the television source is set to HDMI3, the set is switched on, and the cable is plugged into HDMI port 3.

If the laptop is switched ON and booted into either Windows or Ubuntu, it will not recognise when the cable is plugged into the HDMI port.

If the laptop is switched OFF, the cable is plugged into the HDMI port, and the laptop is booted into Windows, the laptop display is echoed on the television screen and YouTube and streaming video is sent to the TV.

If the cable is plugged in, and the laptop is booted into Ubuntu, the HDMI cable is recognised but the display on the TV screen is different from that on the laptop. On the Ubuntu home dekstop laptop display the wallpaper displays with icons down the left, a browser open, and scattered files and icons. The image echoed to the TV screen shows ONLY the wallpaper! No apps, icons, cursor arrow or anything else on the desktop displays on the TV!

Questions
1 Does anybody know how to fix the problem?
2 What other CLI commands do I need to execute to obtain more diagnostic data?
3 Are we looking at a Wayland bug here? If so, where and how do I report it?

Note
The Windows System Information app is far superior in depth and breadth of information and keeps all the information you would want in one convenient and easy to use place.

Hardware
Hisense DVB-T Model:HL32T28PZL PAL B/G television receiver (3 x HDMI ports)
Dell Vostro 2520 laptop (1 x HDMI port)
Intel(R) HD Graphics 4000 (from Window System Information)
Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) Subsystem: Dell 3rd Gen Core processor Graphics Controller, Kernel driver: i915 (from lspci)
(Note: no proprietary graphics drivers found in Software & Updates > Settings > Additional Drivers.)
Dual booting:
* Windows 10 Pro
* Ubuntu 18.04 Bionic Bucky+ LTS

Command outputs
~$ lspci -k | grep -A 2 -i "VGA"
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
Subsystem: Dell 3rd Gen Core processor Graphics Controller
Kernel driver in use: i915

~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
[...]
card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]
Subdevices: 1/1
Subdevice #0: subdevice #0

~$ aplay -L
[...]
hdmi:CARD=PCH,DEV=0
HDA Intel PCH, HDMI 0
HDMI Audio Output
[...]

  • Bucky the Beaver
  • Installing the small program arandr may shed some light on your situation. It will show you graphically all the connected displays and their resolutions. And you can change the relationships between the displays. It's in the standard 18.04 repos christian.amsuess.com/tools/arandr I am guessing your display is getting spread over the TV and monitor in a strange way, and this tool should show you. – Organic Marble Jun 15 '18 at 1:18
  • Organic Marble The problem is that I am displaying a streaming movie in the laptop and using the HDMI ports to connect to a digital TV. Except that the video is not being duplicated on the TV, it is not showing up at all -- only the laptop's desktop wallpaper. – Hedley Finger Jan 10 '19 at 11:59
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When you plug in a digital TV via an HDMI cable, Ubuntu treats this second monitor as an extension of the first monitor -- an enlargement of the desktop. That is why it initially shows just the wallpaper on the TV.

To duplicate the first monitor on the second (your TV), you have to tell Ubuntu to mirror the first display:

  1. Plug your HDMI cable into the computer and the TV set, and turn both devices on.
  2. Click the top RH corner of monitor one. The system menu drops down.
  3. Click the settings button (crossed screwdriver-and-wrench icon).
  4. Choose Devices > Screen Display.
  5. At the top of the Screen Display page, click the Mirror button.* You should now see the display on monitor one duplicated on the TV, enlarged to fit the larger screen.

* If you can't see the Mirror button, make sure the TV is switched on and the HDMI cable is plugged into the TV and computer.

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