[RPi5] Projector shutting off with CEC disabled

cchayre · October 15, 2024 at 1:27 AM

Bit of an odd issue I'm looking to troubleshoot and looking for suggestions on where to start. I have LibreElec 12.0.1 installed on a Raspberry Pi 5. It's a new deployment/set-up. Through testing over a few weeks I am getting a behavior where my projector is shutting off at a consistent interval during video playback. I need to check exacts again but it's in the 25-30 minute timeframe. Example: 25ish minutes into a longer movie, projector will shut off but my receiver and Pi 5 will continue to play. The playback may stutter a second or two after this happens as well but resumes. There are occasions, maybe once every 5 or 6 times I try, where this does not occur. But it is consistently happening every time outside of that.

At first I thought it may be an issue with CEC and my receiver and projector. However, I have disabled CEC (peripherals) from the input settings in Kodi. CEC is NOT a requirement for my set-up. The behavior persists even after disabling CEC.

I have ruled out the projector itself. The behavior does NOT occur with a Roku I have attached to it nor does it with a Windows-based system running Kodi (Intel NUC).

Let me know if anyone has any suggestions on where to begin or what to do next.

**popcornmix** · October 15, 2024 at 7:33 PM

Quote from cchayre

25ish minutes into a longer movie, projector will shut off but my receiver and Pi 5 will continue to play. The playback may stutter a second or two after this happens as well but resumes.

Just to be clear, the projector shuts off for just a couple of seconds then resumes normally?

hdmi cable would be my first guess. What's the hdmi resolution/refresh rate?

For 4kp60 you do need a high quality cable (and mico hdmi -> full size adaptor if you are using a separate one).

Does it still occur if you force hdmi mode to 1080p?

Other tests would be does the issue occur if you connect straight to projector (no AVR)?

Does the issue occur with a normal TV instead of projector?

cchayre · October 17, 2024 at 11:09 PM

No. The projector just turns off. Shuts down exactly as if I were to hit the standby/power button on the projector's remote. I need to hit the power button on the remote to turn the projector back on to re-display the picture. The Pi 5 and receiver continue playback through the process. However, I do notice a brief blip in the audio when this happens.

Resolution is 1080p with 60hz refresh.

I will need to test with a different screen and for straight-to-projector. I have verified the behavior is not occurring with a Roku device or Kodi (Windows) on a NUC plugged into the same AVR (port).

**popcornmix** · October 18, 2024 at 12:06 PM

Quote from cchayre

No. The projector just turns off. Shuts down exactly as if I were to hit the standby/power button on the projector's remote. I need to hit the power button on the remote to turn the projector back on to re-display the picture. The Pi 5 and receiver continue playback through the process. However, I do notice a brief blip in the audio when this happens.

Hmm. If you asked me to create some code that ran on the Pi and powered off the projector without using CEC (which you say is disabled) or DDC (which the pi will never send without running an external program like ddcutil), I'd say that was impossible.

Your projector is choosing to power off for some reason. It could be an intermittent hardware fault of the projector.

It could dislike something about the signal coming from the pi over hdmi (although switching to standby is very surprising for this - normally you would expect a loss of sync, resulting in a temporary black screen, and recovery shortly after).

The likely causes for it not liking the signal (after it being happy for ~25mins) is something marginal - possibly caused by a poor hdmi cable/adaptor, or an inadequate power supply (the 5V from the power supply does go over the the hdmi cable and powers the display/projector's hotplug/edid logic).

Might be worth timing how long playback lasts before failure. If it is always 25min then that would be interesting (but I suspect it is more likely random).

cchayre · October 18, 2024 at 5:34 PM

Right. One of the first reasons I disabled CEC is because the power-off timing WAS consistent. I probably should get a timer out next time to gather the empirical data.

Highly improbable that it's a hardware fault with the projector. No comparable behavior with other devices attached (Roku, NUC).

I may swap out all the cables as well to verify signaling.

HarryH · October 18, 2024 at 8:45 PM

There are issues with projectors if they are overheating, then they shut down after such kind of period. It looks to me that this happens on your setup. Maybe an firmware issue of the projector or AVR with a specific frame rate or possibly a real hardware issue. Do you have an OSD with information about current input signal on your projector to compare the incoming signal with the working ones of Roku/NUC

Which projector and AVR do you use?

cchayre · October 21, 2024 at 1:45 AM

Quote from HarryH

There are issues with projectors if they are overheating, then they shut down after such kind of period. It looks to me that this happens on your setup. Maybe an firmware issue of the projector or AVR with a specific frame rate or possibly a real hardware issue. Do you have an OSD with information about current input signal on your projector to compare the incoming signal with the working ones of Roku/NUC
Which projector and AVR do you use?

Not an overheating thing. Again, can run it for hours with other devices attached and it plays fine. Ex. Just ran a NUC yesterday for around 11 hours without issue.

I'm going to dig more into the signal/frame rate/etc side of things.

HarryH · October 21, 2024 at 10:32 AM

It's up to you that it's difficult to support you. You skimp on details and doesn't provided helpful information about projector and AVR model number and firmware state.

Depending on the kind of projector you using, there are mechanical parts involved which could be affected by the used frame rate and color deep, not only electronical parts. LibreELEC attempt to use the native frame rate of the movie material (mostly 23.976Hz/24Hz) during playback and not the desktop settings. This can make already the different to Roku or KODI on Windows. Then the color wheel inside of a DLP projector may use a different frequency to follow the frame rate of 24 Hz or upscale to 120Hz or something like that. The resulting behavior mustn't be the same if your other sources provide a 60Hz signal instead and therefore not ends in protection mode/overheating of your projector.

To inspect if the RPi5 is really the troublemaker, you should:

enable debug logging : https://wiki.libreelec.tv/support/log-files
reboot
trigger the issue
post the link to the log

PS: Since some other HDMI- and CEC-related corrections are only included in later versions than 12.0.1, you should perhaps also try a current nightly version of LE 12 or 13 (Attention: sorted in ascending order!): https://test.libreelec.tv/12.0/RPi/RPi5/

cchayre · October 22, 2024 at 1:37 AM

No intent on skimping details. When I was posting the previous response it notified me the name of the vendor was a banned word in the forum for some reason. I was in a hurry and omitted that portion instead of editing or obfuscating.