[mythtv-users] rpi4 HD playback profile

[Mike Bibbings]

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.
> 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