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makem
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Joined: Tue Jun 18, 2013 9:22 pm

VNC with 'real' desktop on TV which loses access to the HDMI signal [Solved]

Thu Dec 05, 2019 5:23 pm

I am using x11vnc to successfully connect my Pi4 to my Panasonic TV where I watch movies for perhaps 1% of the time, 99% or the time I use the Pi4 headless via my laptop for other purposes.

I have encountered a problem (well maybe two) and I suspect it may be a problem with the TV end but am unsure.

If we are watching a movie as described above and decide to stop it to do something else and resume a few minutes later and either turn off the TV or just change which HDMI input to use before we return to the movie, we cannot return to the HDMI signal from the Pi4.

It appears that the TV 'forgets' there was a signal after only a few minutes and cannot resume. The signal does still exist as I see it via VNC.

The Pi has only just been set up and still has a USB mouse and keyboard attached. Both will soon (hopefully) be removed. If I move the mouse pointer the HDMI immediately connects and the movie is back. The option -forever is in use.

But, moving the mouse has the undesired effect of cutting the VNC connection and a connection is then refused until I ssh in and reboot which is not really a viable method of resuming.

As I suspect it may be the TV end, I have asked a question in the avforum too.

I am wondering if RealVNC will be recommended ;-)
Last edited by makem on Fri Dec 06, 2019 12:26 pm, edited 1 time in total.

User avatar
makem
Posts: 300
Joined: Tue Jun 18, 2013 9:22 pm

Re: VNC with 'real' desktop on TV which loses access to the HDMI signal

Fri Dec 06, 2019 12:32 am

I find that disabling hdmi_blanking is not an option in the Pi 4. The HDMI is blanked after (15?) minutes and is one explanation why the TV cannot reconnect.

Using ssh I installed xscreensaver to check if I could use that to disable blanking and found that when it opened the TV screen woke up. The program complained that the engine was not active on display 0:0 (the TV I presume?) with an option to enable it. I did not enable it.

It does tend to show that the HDMI can be refreshed or rebooted but I cannot find any way to do that by a command.

I suppose I could use that program to wake up the TV screen as a last resort!

I also find that it is the fact the I play movies with the Pi 4 which causes the VNC connection to be dropped. I have used the VLC media player for this but will look for an alternative player to check if it is the player which is at fault.

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makem
Posts: 300
Joined: Tue Jun 18, 2013 9:22 pm

Re: VNC with 'real' desktop on TV which loses access to the HDMI signal

Fri Dec 06, 2019 11:02 am

Uninstalled xscreensaver and instead used option 2 from this page:

https://www.geeks3d.com/hacklab/2016010 ... -raspbian/

Code: Select all

[email protected]:~ $ sudo nano /etc/lightdm/lightdm.conf
[email protected]:~ $
Added:

[SeatDefaults]
xserver-command=X -s 0 -dpms

The following day the desktop was active :D

I also changed the memory split to 256 for GPU and will see later today if that cures the media causing disconnections.

Edit: Increasing the GPU memory stopped the VNC disconnections but using VLC there is some slight jerkiness in the output. Omxplayer may cure this but it has failed to play one video which VLC played. Needs a codec for it. I don't suppose it is possible to copy VLC codec to Omxplayer, that would be to easy!

Never mind, I can mark this as solved, both problems having been solved.

Edit: Increased memory to 512 (maximum recommended) for GPU

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