MythTV Official Community Forum

Recently built a new Myth system using a 4GB RPi4, using MythTV-Light 0.31.
I've noticed that playback of UK Freeview HD recordings seems not quite right. There are occasional little "micro jumps" in the decoded video.
I've tried setting up a new playback profile as per the advice in the wiki, but it seems to make no difference.

Googling around, I've seen reports that the frontend on a Pi4 runs better on 0.30 than 0.31.
But before I start again with 0.30 in the (possibly futile) hope that it will fix things, I just wanted to check here with the more experienced guys for their comments.
Is switching to 0.30 the easiest solution for a Pi4 frontend?
Is there other inexpensive hardware that will run a full Myth frontend better than a Pi4? (I've experimented with a Firestick, but the lack of buttons on the remote impacts usability).

I briefly tested MythTV v30 on RPi4 and the resulting video display with mythfrontend was not perfect either (similar to v31).

Because MythTV v30 still supported OpenMAX I suspect that it would display better on an RPi2/3 which have the Broadcom Videocore IV GPU and also support a purchased MPEG2 license. Note that I have not tested such a v30 configuration with RPi3 myself. I am curious as to your results if you do test this.

The RPi4 uses a newer Broadcom Videocore VI GPU, and support for this new GPU is still under development. For example the LibreELEC team is still working with the Raspberry Pi folks to implement deinterlacing support for the RPi4. See LE10 & deinterlacing in RPi4.

Since much of my OTA content is ATSC MPEG2 1080i I have relegated the RPi4 to backend use only, and in the meantime resorted to using Peter Bennett's great Android Mythfrontend on a 2017 NVidia Shield. Note that solid playback performance is available on the RPi4 if one uses Kodi with the MythTV.PVR PVR client add-on.

Thanks for the info.
It looks like perhaps the reports I saw about 0.30 being more dependable may have been about Pi2/3.

I wouldn't really describe the Nvidia Shield as "inexpensive"!
I think I'll try out Kodi with MythTV add-on and see if its interface is acceptable (to my wife as well as me!)

I think the quality of the picture for different frontends is very subjective and dependent on type and format. That being said, the v31 on RPI4 has improved since I originally said v30 was better than v31.

If I was forced to use an RPI4 4GB as a combo BE/FE I'd have no issues with the Backend, but as a Frontend I'd have to accept Kodi with the mythtv PVR addon. If that was acceptable, great. But if not, then I'd add a FireTV 4K with Leanfront to the RPI4 backend.

OK, latest status is that I installed LIBREelec on a Pi4 and added Kodi's MythTV plugin.
I was able to configure it, and it said it successfully connected to my 0.31 backend.
But the "Run" button is disabled. I can't see any way to actually run the add-on. Any ideas?

EDIT: OK, scrub that. I have discovered that it runs automatically, and all you have to do is go to the Kodi home screen and bring up Recordings from there. Have successfully played a recording. Let's see how I get on with the (radically different to MythFE) interface.

cliveb wrote: ↑

Mon Apr 26, 2021 10:13 am

OK, latest status is that I installed LIBREelec on a Pi4 and added Kodi's MythTV plugin.
I was able to configure it, and it said it successfully connected to my 0.31 backend.
But the "Run" button is disabled. I can't see any way to actually run the add-on. Any ideas?

I use RPI4 with LibreELEC with mythtv pvr addon, plus Netflix and Prime VOD addon in my garage shop. My backend is on a PC in a closet in the house for use by all my FEs.

Once I configure the IP for the Mythtv addon I go to the home screen of Kodi and move to TV. There is no "Run"

Regarding NVidia Shield: The Amazon Fire stick 4K works as well or better for a fraction of the price.

For mythfrontend you need a fire stick 4K even if you are not playing 4K content.

Another frontend option is leanfront, which works on fire stick non-4k as well as fire stick 4k and NVidia Shield.

As Peter says, Leanfront on a FireTV stick works great. I use my garage as an electronic project workshop and on pretty weather days, I back the car out and I have the complete 2 car garage for use as a sports bar for me and my neighbors. Yesterday afternoon I had the big Sony with a FireTV 4K stick ($40) showing NHL Hockey streaming from the mythtv backend using Leanfront. On my smaller TV I had an RPI4 running LibreELEC with kodi-pvr-mythtv streaming PGA Golf. No one had any complaints about either picture quality.

jfabernathy wrote: ↑

Mon Apr 26, 2021 1:39 pm

... No one had any complaints about either picture quality.

Yeah, but how much beer had been consumed?

Steve Goodey wrote: ↑

Mon Apr 26, 2021 1:49 pm

jfabernathy wrote: ↑

Mon Apr 26, 2021 1:39 pm

... No one had any complaints about either picture quality.

Yeah, but how much beer had been consumed?

while True:
drink --option (beer | wine | bourbon | vodka)

OK, after further tests, I have come to the conclusion that the problem I'm experiencing must be something to do with the HDMI protocol being negotiated between the Pi4 and the TV. SD playback seems fine in all cases, but for HD playback:

1. If I connect the Pi4 to an old TV (LG 32LS5600-ZC), everything is just great. HD playback is fine, using either the MythTV-Light native frontend or the Kodi MythTV add-on.

2. When I connect the Pi4 to my shiny new LG OLED55GX6LA, the native MythTV-Light frontend is *almost* fine, but I see some "micro jumps" in the picture now and then. Running the Kodi MythTV add-on, it's completely unwatchable: bigger jumps in the picture, and the audio is badly out of sync - even though Kodi is reporting very low CPU usage.

(Note that all this is using a Pi4 running only a front end - the MythTV backend is on another Pi4 on the network).

Now, the problem is that the new LG OLED TV has a bewildering variety of picture setup options, and when I Google for Pi4 HDMI configuration settings, there is an equally bewildering number of options. I guess I can try going through a matrix of every option on both devices hoping to find a combination that works. But before I set out on that daunting task, can anyone here offer any suggestions as to what Pi4 HDMI settings I should start with?

OK, I think I have this sorted, and thought I should explain it here in case it helps anyone else.

I used the tvservice command to check what HDMI mode was in use and what was available.
On the old LG LED TV (where HD playback was working fine), tvservice -s showed that the HDMI output was set to 1920x1080@60Hz, but on the new OLED TV it was set to 3840x2160@30Hz. I edited /boot/config.txt to force it to use 1920x1080@60Hz (hdmi_group=1, hdmi_mode=16), and now HD playback seems fine on the OLED TV. Fortunately I'm only playing UK Freeview HD content (which as I understand it is broadcast in 1080i), so don't need higher resolution than this.

tvservice -m CEA on the OLED TV shows that 3840x2160@30Hz is its "native" mode. My guess is that the Pi4 agrees to operate at that setting when negotiating with the TV, but doesn't actually have enough grunt to support it.

For European broadcast I would go for 1920x1080@50Hz.