[mythtv-users] Hard frontend crash with vaapi on Ubuntu 20.04 and Mythtv 31

OpenMedia Support support at openmedia.co.nz
Tue Jun 1 14:16:28 UTC 2021

> On 6/1/21 7:05 AM, OpenMedia Support wrote:
>>> On 6/1/21 3:38 AM, OpenMedia Support wrote:
>>>> I'm running an Intel N3150 based NUC as a dedicated frontend for
>>>> MythTV
>>>> and it keep getting hard crashes during video playback with VAAPI. Id
>>>> appreciate some guidance on how to best debug the problem.
>>>> Hardware - Gigabyte Brix Intel N3150 / 4GB Ram / 120GB SSD
>>>> OS - Ubuntu 20.04 LTS - regularly patched
>>>> MythTV Backend - on different hardware with DVB-T and DVB-S cards
>>>> MythTV Frontend - Lastest version from the PPA -
>>>> http://ppa.launchpad.net/mythbuntu/31/ubuntu
>>>> Video playback currently uses a custom VAAPI profile, but the out of
>>>> the
>>>> box VAAPI profile also has issues. It appears to occur when playing
>>>> H.264
>>>> based content. Our DVB-T FTA service is H.264 for both HD and SD
>>>> material.
>>>> It can occur when we're simply watching a show, and the video / audio
>>>> freezes and I need to hard-reset the Brix hardware.
>>>> I've configured for
>>>>    - max_cpus = 3
>>>>    - deinterlacer - low:shader:driver
>>>>    - decoder - vaapi
>>>>    - videorender - opengl-hw
>>>>    - skiploop - 0
>>>> I'll try and reproduce with "-v playback" enabled but at present there
>>>> is
>>>> nothing obvious in the frontend or system logs when the crash occurs.
>>>> I'd really appreciate it if anyone else seen similar issues and could
>>>> provide guidance.
>>> I have a NUC i7-1165G7 and it has Iris graphics.  I can't get VAAPI
>>> to
>>> work at all. I have to use OpenGL low quality deinterlacing. When I use
>>> VAAPI it crashes with code 139. I can't run higher than low
>>> deinterlacing because the pictures tears about 10% from the top of the
>>> screen.
>>> Luckily, I didn't buy the $800 NUC as a mythtv frontend only. Iris GFX
>>> and Mythtv aren't a good solution for sure.
>> The N3150 Brix was relatively cheap and generally makes quite a nice
>> front
>> end, and now it has an SSD is effectively silent.
>> Just had a fresh hard crash with "-v playback" and all I can see is the
>> following as I had an SSH session tailing the frontend logs.
>> Jun  1 21:49:37 mythfe1 mythfrontend.real: mythfrontend[1900]: I
> Are you able to get into ssh to kill the frontend when it locks up? I
> would say the thing to do is enable core files by setting the limit and
> disabling Ubuntu crash logging, then when it happens run kill SIGQUIT to
> create a core dump which can be analyzed to see where the hang occurred.

Afraid not. This is a hard crash and I loose my SSH sessions. I've been
running a couple of sessions to tail the mythfrontend and system logs and
they become responsive until I reboot the hardware.


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