[mythtv-users] rpi4 HD playback profile

[Tim Draper]

 ---- On Sun, 17 May 2020 16:32:28 +0100 Mike Bibbings <mike.bibbings at gmail.com> wrote ----
 > 
 > 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.

correct.

 > Pi 4 must be in console mode (not Desktop)

already done & using the wiki recommended cmdline to run it. Cant say desktop vs console made any difference to HD playback.

 > 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
 > 
tried both mode=31 (1080p50) and mode=16 (1080p60) which is what EDID seems to prefer but no difference.

Found that using Software decoding works for HD content and it's fixed all my issues (with a brief 10minute test)
- interlaced content correctly detected - no more manually switching from progressive to interlaced.
- 1080i content no longer looks extremely jagged (as in an (anti)aliasing type jagged, not combing you get with nodeinterlacing) reguardless of deinterlacing settings.
- More of an observation; cpu jumped from around 10% to 50% across all cores. not a big problem as allows me to use the 'ondemand' govenor since the mhz threshold has been exceeded.
- stuttering has gone. 

Currently i've set 2 playback profiles. a HD one specifically for 1920x1080 that uses 'standard' decoder, 4cores, & medium single rate deinterlacer.   the SD one catches anything <1920 <1080 with v4l2 decoder, 4core, no single rate & medium double rate deinterlacer.
I stumbled upon something on the official rpi forums last night that sugested there is some issue with hardware h264 content which made me try software decoding.

if my understanding of the rpi page & v31 release notes wiki that v4l2 should be used for all content on a rpi4 FE, and that my findings are correct, then the v4l2 implimentation on rpi4 still needs work (or atleast wiki correctly reflects the playback profile required).

i also mentioned in another post in this thread that i was having issues with AV randomly blanking out. Appears the the tv input HDMI4 was at fault. moving to HDMI1 didnt show any blanking issue at all yesterday.