[mythtv] render2019 comments

Tim Pletcher pletchtd at gmail.com
Tue Oct 22 22:10:14 UTC 2019


On Tue, Oct 22, 2019 at 8:38 AM Mark Kendall <mark.kendall at gmail.com> wrote:

> On Tue, 22 Oct 2019 at 00:27, Tim Pletcher <pletchtd at gmail.com> wrote:
> >
> > I just gave the 2019-render branch (devel/2019-render
> v31-Pre-1095-gc7eabdaf86) a try on one of my frontend machines.  The
> frontend is home-built Apollo Lake Celeron J3455 system running Xubuntu
> 18.04 with Vaapi version 1.10. The frontend is used almost exclusively for
> viewing NTSC LiveTV and the output is configured for a 1920x1080 at 59.94
> modeline.  The frontend is configured with a VAAPI2 profile with Vaapi
> acceleration and opengl-hw High quality deinterlacing.
> >
> > Everything works great with the exception of one issue:
> > On 1920x1080i channels where deinterlacing is in use, any overlaid info
> flickers in the overlaid section in the top 1/4 or of the screen (see video
> here: https://youtu.be/PXospaUX1lo). The same flickering behavior is also
> observed if viewing a 1920x1080i at 30fps recording so this doesn't appear
> unique to LiveTV.  The overlay flickering is not present in any
> circumstance when viewing 1280x720 at 60 content where deinterlacing is not
> in use.
> >
> > To compare, I also tried the render branch on another machine with an
> Nvidia card (GT 1030 / driver version 390.116).  Using VDPAU acceleration
> and opengl-hw deinterlacing on this frontend, the overlay flickering is not
> present with either interlaced or progressive content.
> >
> > Any hints on why I might be experiencing this with VAAPI acceleration on
> my Apollo Lake machine?
>
> Tim,
>
> Thanks for the video. Very helpful - though a curious issue.
>
> This can only be a performance problem as the OSD is the last thing to
> be displayed - certainly not a vsync problem as the video is fine. As
> a sanity check can you possibly produce a log with "-v
> playback,gpu,gpuvideo" logging.
>
> Also worth going into the detail of the display profile page, if you
> haven't done so already, and ensuring that you have everything setup
> properly - as previously mentioned, the display profiles aren't
> currently migrated completely. You'll need VAAPI acceleration then try
> setting deinterlacers to high quality and enabling both shaders and
> driver deints. If you still see the issue, try dropping the quality of
> the deinterlacers.
>
> Furthermore, again if you haven't tried it already, try to force EGL
> from the command line - which gives much better VAAPI performance.
> Something like:
>
> QT_XCB_GL_INTEGRATION="xcb_egl"  mythfrontend -v playback
>
> I'm not sure how powerful that GPU is or what features it supports -
> so it may be falling back to some basic VAAPI deinterlacing or OpenGL
> shaders. Logs would confirm - or alternatively if you try a different
> theme (e.g. MythCentre-wide) it will show which deinterlacer is in use
> in the Debug OSD screen.
>
> All that said, on reflection I think this is an OpenGL flushing issue.
> Flushing is currently disabled - I'll add it back by default. I'm
> pretty sure that will fix the problem.
>
> Hi Mark,

Thank you for your response.

I tried the command you suggested to force EGL
(QT_XCB_GL_INTEGRATION="xcb_egl"  mythfrontend) and that fixed the issue
entirely!

I also grabbed a couple of frontend logs with the suggested "-v
playback,gpu,gpuvideo" options and posted them here:
    https://gist.github.com/pletch/eba2c199441604539b8627abdc48e219
Two logs are posted there with the first being a log captured with the EGL
force command line option on (no flickering) and a second without this
option (flickering present).

I'll use the force EGL option by default going forward.

Regards,
Tim
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