Lagging Mythtv Playback, Living Room Only!
 

I did a fresh install of Ubuntu 18.04 to my htpc / server in the living room. This machine is serving media, mythtv, pxe boot using ltsp to boot a media center in my bedroom. It direct boots to Kodi for media center in living room. All media is watched or accessed through Kodi.

The TV in the living room is a 4k Samsung. I've never had issues until upgrading to 18.04 and the new Mythtv. Both my laptop and my pxe boot machine in the bedroom are 1080p.

Mythtv playback is practically unwatchable in the living room. It stutters visually, the audio gets out of sync after a few seconds of watching. I have checked all logs, nothing looks out of the ordinary. However at the same time, everything plays just fine on my bedroom htpc (pxe booted), and my laptop over wireless. No glitching, stuttering, nothing. Just the living room is having this problem.

Suffice it to say the wife isn't happy right now. And I cannot for the life of me figure this out. I can rule out the network being the problem, as Mythtv is on the same machine that is having the issue, yet works fine on wireless to laptop as well as the bedroom htpc. I can rule out bad storage devices, smart tests show just fine, and again everything else including local media plays perfectly well. I get transfer rates of 70-80 megs between the main storage drive and another for testing. I can rule out Kodi and Mythtv both as they work flawlessly on both my laptop and the bedroom machine, all on 18.04.

The only thing left that is different is the 4k tv in the living room. I don't know if this is a buffering issue or what. I've ruled out the HDMI cable, although everything else playing fine kind of kills that issue. I also am figuring it could possibly be a driver issue. This installation was done with debootstrap from the other installation, but I don't know what should be added that the packages didn't add themselves as dependencies.

I am at a total loss right now. I have tried to activate an account on the Mythtv forums for a month for other reasons, never do get the activation email. I have no idea what the problem here is, or if it can be fixed.

Help me Obi-wan-kenobi! You are my only hope!

I'm no expert. My Mythtv is on my pc and just works. But if I have serious issues I use Mythtv forum. Have you tried that?
https://forum.mythtv.org/index.php.

Been trying to get the activation email for a long time. Never shows up.

I'm in the same boat as you -- the activation emails from the MythTV forum are never delivered. Their advice to "Contact the Admins" is a bit hard to follow, since you have to be able to login to do that! Almost as frustrating as the MythTV sound problem I'm having...

As to your MythTV problem, have you tried hooking up your living room machine to one of your other 1080p TVs? It does kind of sound like a video driver problem to me. What is the graphics hardware/driver on that machine?

It is an AMD APU, Kabini Quad Athlon, 25w tdp. Should mention that I went for broke and reinstalled 16.04 to another lvm partition and configured. It's working just fine on 16.04. Somewhere something is different between my installs but I cannot for the life of me figure out what, or even how to chase it down if it's a missing package or something.

I use nVidia chipset graphics on my MythTV boxes (2), and I find that I have to install the proprietary nVidia drivers to get it to work properly even at 1080P. It's marginal, not terrible as you described, but I suspect that at 4K resolution it might well break based on what I've seen. The proprietary drivers never have the slightest hiccup at 1080P. I wonder if there is a similar issue for the graphics cores in your AMD APU setup?

The 16.04 install actually works ok at 4K resolution? Is it the same MythTV version on 16.04? I'm running 0.29 on my 18.04 installs.

If you open the "Software and Updates" Ubuntu app there is a tab for "Additional Drivers". If you go there and let it search does it find any other proprietary drivers, particularly for your graphics hardware? If it does it might be worth giving it a try.

16.04 is working fine. In order to keep my already upgraded database I am running an 18.04 LXD container with mythtv inside it. Mariadb is on the host.

There is no Software & Updates on this machine. It is for all intents and purposes a headless box as far as management goes. Everything is over ssh. The only gui it has is direct boot to Kodi, nothing else. Ubuntu-drivers doesn't show anything proprietary available. When 16.04 dropped they eliminated Fglrx as I recall. Switched entirely to open source, either radeon on amdgpu. It is currently using the radeon driver just like on 16.04.

Are the MythTV video profiles and interlacer options the same on both setups? That's about the only other thing I can think of to look at offhand.

It sure would be nice if someone on this forum who has a valid account on the MythTV forum would log in there and find out from the admins what is up with the account activation emails. Or perhaps forward the email address of one of the MythTV forum admins to us so we can work with them directly on the activation problem. Getting access there probably means a greatly increased chance of trouble-shooting both of our MythTV problems successfully.

Only thing i did when migrating to 1804 is re add my tuners. Didn't touch.any other settings.

I was running an older 14.04 version on my two boxes and didn't migrate -- I reinstalled from scratch with a new quad-tuner card and it all went pretty smoothly. I even think the surround sound settings on my "master" machine were working fine, but an update broke them and I am baffled. Surround sound comes out of the front speakers, not the surrounds.

I wonder what would happen if, just as a test, you re-installed from scratch using 18.04?

Is why I'm so confused. I've done a scratch install twice now, same results. Yet installing 16.04 exactly the same, save the version it works just fine. It's very annoying.

I made contact with one of the MythTV Forum admins on IRC. He says he'll look into the activation email problem.

Ok. You should be able to get into the MythTV Forum now -- the admin I contacted on IRC found and fixed the problem and I am now active in the forum.

I tried logging into the forum again and got a message that my account had not been activated. There was a link to resend the activation email (enter username and email used for original registration) and the activation email came within one minute. Good luck with your problem on the forum!