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

[Peter Bennett]

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.

Peter