Advice needed for handling buggy TV

kwibox · February 1, 2023 at 11:11 PM

Hi!

I have a rather annoying problem and would really appreciate some help debugging. Or actually: I already kinda have drawn the conclusion that the TV is the culprit; not playing nice during resolution/refresh rate changes, showing quite buggy behavior, but other options or tips are welcome.

Problem:

I get signal dropouts, most of the time the signal comes back after a minute or so, but not always. The dropout happen 999 / 1000 after stopping the playback of a video. It happens more frequently when i change the resolution of a video during playback or when I played HEVC 10 bit video 1080p (= stopping the video causes the signal to dropout). During playback (after change of the resolution) the audio drops out every 3 seconds.

I also get continuous dropouts or flashing screens when re-setting the gui resolution to 1080@60. This probably needs some more explaining:

A fresh install of LE sets my default GUI resolution to 1080@60 (wiki says it should be 4K?). When i set it to something else, e.g. 4K@30 and then set it back to 1080@60, the TV does not detect a signal or it continually flashes the screen.

HW:

Raspberry pi 4 (4 GB ram model, original powersupply)

LG 49UF640V UHD TV, Raspberry is connect through HDMI port no 2 (HDMI version 1.4, so max 4K@30fps)

TV is from 2015, so quite old to modern standards (one of the first mid-tier 4K tv's)

TV should support 4k 30, 24, FHD 24, 30, 50, 40

Tried LE 10.0.4 and 10.0.95, no difference.

TV is updated to latest FW.

Log:

http://ix.io/4mQ0

Tried the original RPI micro hdmi cable and an aftermarket good quality shorter one. The shorter one works quite better: the original one has continuous signal dropouts...

I followed the wiki advisory (turbo on, set gui to 1080p60, enable supported modes), checked ports for damage or debris etc.

After diving in the logs, the following happens during the signal dropout:

Code

2023-02-01 22:07:05.775 T:1143     INFO <general>: VideoPlayer: OnResetDisplay received
2023-02-01 22:07:05.778 T:1389     INFO <general>: CVideoPlayerAudio: display reset occurred, checking for passthrough
2023-02-01 22:07:05.783 T:1389     INFO <general>: CDVDAudioCodecFFmpeg::Open() Successful opened audio decoder aac
2023-02-01 22:07:12.753 T:1143     INFO <general>: VideoPlayer: OnLostDisplay received
2023-02-01 22:07:12.754 T:1143     INFO <general>: GLES: Maximum texture width: 4096
2023-02-01 22:07:12.792 T:1143     INFO <general>: VideoPlayer: OnResetDisplay received
2023-02-01 22:07:12.792 T:1389     INFO <general>: CVideoPlayerAudio: display reset occurred, checking for passthrough
2023-02-01 22:07:12.796 T:1389     INFO <general>: CDVDAudioCodecFFmpeg::Open() Successful opened audio decoder aac
2023-02-01 22:07:24.107 T:1143     INFO <general>: VideoPlayer: OnLostDisplay received

This message repeats a couple of times after which, in this case, the signal returns.

Questions:

- any advice how to further debug?

- other people experiencing weird of buggy behavior with this TV?

The most stable setup at this moment is setting a fixed resolution and refresh rate and letting kodi do the up or downscaling e.g. not changing the resolution/refresh rate/or color-bitness during playback. But i would like to be able to watch movies in 24fps (1080p and 4K) and tv shows in 50/60 fps (1080p). Don´'t care about HDR because my TV does not support any. Any advice how the set this up?

I tried my best to describe the issue as clear as possible, but its kinda pseudo-random. All advice is appreciated!

**chewitt** · February 2, 2023 at 10:32 AM

Do you have any other devices to attach to the same HDMI port? .. perhaps an older RPi board, laptop, etc. and does the TV exhibit similar behaviour when display resolutions are changed?

**popcornmix** · February 2, 2023 at 11:18 AM

Code

2023-02-01 22:07:24.107 T:1143     INFO <general>: VideoPlayer: OnLostDisplay received

I suspect this message is hotplug related.

Not sure if a dodgy cable is causing spurious hotplug disconnects, or the TV is generating them for some reason.

With LE11, try adding (make sure you are using first hdmi connector - closest to power socket) :

Code

video=HDMI-A-1:D

to the end of cmdline.txt (on same line).

If that doesn't work, try:

Code

vc4.force_hotplug=1

instead.

kwibox · February 4, 2023 at 10:56 AM

popcornmix thanks for your advice, 'll wil try it.

Edit: none of two suggestions work, but they do stop the flashing (now its just plain "no signal¨").

chewitt it gets even stranger; only 4k capable device I have is an PS5, which I had connected on the hdmi2.0 port (port no 1). So i swapped the PS5 to HDMI port 2 (hdmi 1.4).

So I expected the PS5 to switch back to 1080p or 4K 30. I was quite surprised to see the console spitting out 4K@60 just fine (tv also reports getting a 4k60 signal). Also no problems switching resolutions back and forth (720p, 1080p, 4K), no dropouts. Only thing its not supporting UHD deep color (chroma sub sampling) ... Very weird.

I prob also try forcing the Rpi4 to 4k@60 and see what happens. What i understand is that most 4k videos don´'t have UHD deep color anyway.

Edit: nope is not working, which was to be expected after googling:

TV hdmi port 2 does seems to support 4k60, but only 4:2:0 (or 4:2:2?), which the rpi4 does not support? The PS5 does support it.

Is there a way to set the chroma sub-sampeling mode used by the RPI?

Prob I'll set it to 4k30 and let kodi do the upscaling. I have only FHD content for now, will add 4K. Changing only the refresh rate works well and I don't need 50/60fs support (TV has no problem supporting 24fps and movies/tv shows look better in it anyway).