[mythtv-users] rpi4 HD playback profile

[John]

On 17/05/2020 21:21, Monkey Pet wrote:
> On Sun, May 17, 2020 at 8:34 AM Mike Bibbings <mike.bibbings at gmail.com 
> <mailto:mike.bibbings at gmail.com>> wrote:
>
>     On 17/05/2020 13:31, Tim Draper wrote:
>     > i give up... spent 2-3 days on getting my new rpi4 (2gb, with
>     256mb GPU ram assignment) to playback HD content smoothly and just
>     can't. playback profile is setup to use V4L2 codecs, and I've
>     upped core count to 4. Tried none, software, oGL and driver
>     deinterlacers and disabled deblocking to try and improve things
>     but non of them really fix the issue, just make it worse depending
>     on system load.
>
>
> 1. Disable the Desktop Environment
> 2. Overclock it just a bit
>
> I listed a few other things I tried in 
> https://forum.mythtv.org/viewtopic.php?f=46&t=3791 also the link has a 
> bit more details. Also see https://www.mythtv.org/wiki/Raspberry_Pi.
>
> Good luck, i am happy with mine, but I basically use it for HDHomerun 
> MPEG2 OTA recording playback.
>
> The two above did it for me. Mostly it was the desktop environment.  
> Then a slight overclock, now things are smooth.
>
>
>     > rpi4 not overheating (around 72c during playback and running the
>     full 1.5ghz)
>     >
>     > seems like i could be dealing with multiple issues too.
>     > first, any playback of HD content feels like it's dropping
>     frames. also seems to jump every few seconds. almost like a rpi3
>     does with HD content with 'ondemand' governor.
>     >
>     > second is HD deinterlacer. LiveTV seems to correctly detect HD
>     content as interlaced (correct; UK is 1080i broadcast). Recorded
>     program gets detected as progressive. I'm having to change this
>     manually every playback to interlaced.
>     >
>     > Third, very intermittent screen blanking where hdmi video&audio
>     both cut out but resume again after 2-3 seconds. doesnt seem to be
>     related to anything specific and seems completely random. I'll be
>     placing an order later for a new HDMI cable to see if that helps
>     but not sure this would have an effect on the above..
>     >
>     > thanks for any help on this - its driving me insane !!
>     > _______________________________________________
>
>     I am assuming that you are trying to get mythtv-light  31 working
>     from
>     https://www.mythtv.org/wiki/MythTV_Light on current Raspbian Buster.
>
>     Pi 4 must be in console mode (not Desktop)
>
>     In /boot/config.txt make sure screen resolution is correctly set
>     and no
>     higher than 1920x1080 with either 50Hz or 60Hz refresh (depends on
>     your
>     broadcast standard.
>
>     For example in UK hmdi_group=1 hdmi_mode=31 gives 1920x1080 at 50Hz
>
>     There maybe further complications depending on your TVs maximum
>     resolution, which requires an eglfs json override file, otherwise qt
>     (part of mythfrontend) will use data from EDID which is likely to
>     cause
>     incorrect resolution/fresh during playback or LiveTV. I have a 4K
>     TV and
>     playback tries to use a much higher resolution and the wrong refresh
>     frequency (30Hz with Pi4 in default settings). I also have an HD
>     TV and
>     this uses 60Hz instead of 50Hz.
>
>     I have a script run_mythfrontend.sh which launches mythfrontend
>     and sets
>     up the required override based on hdmi_group and hdmi_mode
>     settings in
>     /boot/config.txt.
>
>     The script is available from my github repository at
>     https://github.com/MikeB2013/pi-utils
>
>
>     Mike
>
>
>
>
>
>
>
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Similarly I have tried many settings to get Pi 4 Jitter free playback. I 
suspect its the UK HD broadcact standard (1280i 25Hz) that's screwing 
this up. I have not seen any bad reports from US users. Kodi/Mythbackend 
is better but still not perfect showing a little jitter.

When using Mike's script (thanks for the build script) to run in console 
mode things get worse, the screen flickers and the graphics flash. I 
have not had a chance to chase the issue down.

Conclusion use Kodi.

Pi makes a great backend though.

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