Auto Contrast / Auto Dim Issue

Hi guys
I know this is my first post here but I am having the strangest problem.
I have been running OSMC on my Raspberry Pi 2 for a few years now and have never had this problem until I got myself a new Sony VPL-DX102 projector a couple of weeks ago.
When watching content downloaded off the internet and through Kodi on a Raspberry Pi, I notice that on darker sequences, the image is auto shifting contrast or is dimming or brightening up depending on the image on screen. Its particularly clear on most of the latest episodes of Game of Thrones and the likes, but on other content as well. The same content when played back through VLC on a laptop following the same signal path as the Raspberry Pi using the same HDMI cables has no problem. Even more strangely, the problem doesnt happen on my Panasonic C10 television which is connected to the same AVR using a HDMI splitter.

Here’s my current config

  • Denon 1612 AVR

    • Inputs

      • Rasberry Pi with Kodi 16.1
      • PS3
      • Set-top Box
    • Outputs

      • Panasonic C10 Television
      • Sony VPL-DX102 Projector

Since the AVR has just one HDMI out, I have a splitter between them that splits the one to two HDMI’s for the projector and the television.

Now for the interesting bits.

  • Cannot see any contrast shifts on the television from any source
  • Cannot see contrast shifts on projector from any other source other than Kodi (raspberry pi 2)
  • Tested by watching the multiple different content sources from tv shows to movies through the Pi and then disconnecting the cable and connecting the same HDMI to a Microsoft Surface Pro 2 and viewing the same content through VLC. No contrast shift on television. Contrast shift on the projector.

There are no settings on the projector that are controlling this. If there was, it should have happened on other sources as well.
Cant find any settings on Kodi either that can do this. Surprising its not happening on the television.
I am totally lost.
Was about to send the projector back to Sony for replacement till I realized that the problem was happening only on video playback and not on any other part of the GUI or video addons like Youtube and Vimeo videos. It happens primarily on television shows and movies. Tried changing the video acceleration modes and also the hardware players being used. Made no difference.

The issue is very subtle but almost makes the projector unusable with Kodi for me. It keeps switching contrast on dimly lit scenes. I am sure its doing it elsewhere as well, but its not as obvious.
Can someone please tell me whats going on. I confirmed that I am not the only one seeing it by showing it to the Sony engineer who visited this morning and he was perplexed as well.
Three friends also came over and without any feedback from my side to them all asked me why the contrast was constantly switching.

Help! :worried:

Test without the HDMI splitter. Also test with the pi connected directly to the protector. Also test different HDMI cables.

Hey, thanks for replying.
Here’s what I’ve tested so far and it all reverts the same problem

Directly connected Pi to the projector and the problem still exists.
Tested with another HDMI cable that I use with my computer and problem still exists.

Tested the current signal path to the Pi with my laptop + vlc, no problem with the same videos
Swapped the HDMI cables from the splitter to the TV and Projector, problem still shows up on the projector

This is a strange one. I have no idea where its originating from, but it only seems to happen between the Pi and the Projector. The PS3 and Digital Setupbox have no such issues through the same splitter + avr.
In fact, the PS3, STB and Pi have no issues with the same splitter + avr going to my Panasonic TV.
Just the Sony + Pi seems to be doing some weird shit.

Here’s another guy talking about something similar on the Kodi Forums. Its so difficult to explain or troubleshoot cause I cant for the life of me figure out whats happening.

I work in the technical dept of a video post studio. So i am fairly comfortable with troubleshooting video based issues. This has just perplexed me cause I cant figure whats happening with one output over the other. The splitter should cancel out any discrepancies in the HDMI CEC too. But i have definitely narrowed it down to the Pi + Projector combo thus far.

Any other insights?

The problem is pretty clearly your projector.

Kodi doesn’t have any sort of “dynamic contrast” functionality or feature, so there’s no opportunity for it to do something like what you describe, and I have certainly never seen this effect on any version of Kodi on any platform. (Pi, Vero, Mac, PC)

On the other hand most if not all modern TV’s these days have dynamic contrast modes which are on by default and typically turned up quite high. An HDMI projector that is primarily designed for TV use rather than PC use almost certainly has a dynamic contrast mode too.

I would be checking through all the image settings on your projector and turning off as much image processing as possible. On my Samsung TV it had a very obvious dynamic contrast effect that looks like what you describe - until I turned off all the dynamic contrast settings on the TV.

Thanks for chiming in @DBMandrake
My first guess was absolutely that its a projector thingy. Thats the reason I called in the Sony engineer as well for a site visit. Here’s why we are hitting a roadblock.

The first test we did was connecting Kodi directly to the projector over HDMI and viewing GoT S06E06. Its an MKV downloaded off the internet. We could see the image auto contrast only in the dark scenes, especially the ones indoor when Sam is eating dinner with his folks.

We repeated this test, this time running my Microsoft Surface Pro 2 connected to the same HDMI cable over a mini DP to HDMI and watched the same content on VLC. This time around, no auto dimming or brightening happening in the same sequence.

I then went back to the original configuration and connected the Pi to the AVR and removed the splitter thereby sending the signal directly to the projector from the AVR. This time, I watched Sicaro, the Roger Deakin’s shot film again downloaded off the internet. The sequence inside the tunnel towards the end of the film is what i forwarded to. Again, noticed the image automatically brightening and darkening according to the scene on screen.
Watched the same thing over VLC using the Surface Pro 2 and a PS3 (after converting to mp4), there was absolutely no difference in contrast and no dimming or brightening either.

This is why its such a difficult thing to sort out for me. I have repeated these tests with the same results using different source material, different players, different content, different cables, etc etc, all of them end up with the combination of Kodi + projector resulting in the problem, where as STB + projector or PS3 + projector or Laptop + projector does not have the problem.

Trust me guys, its the strangest thing ever.

Also to answer your question, I have gone over every single setting on the projector. There is absolutely nothing that controls auto brightness and dimming. If there was, it should have happened across those other sources as well. Roadblock!!!


Also please note, it doesn’t happen on the Panasonic Plasma TV connected up to the same Pi.
I linked up this other post from another user on the Kodi forums.
He had exactly the same problems going from Kodi to his SONY television.
I wonder if its something to do with how this combo works together.
So strange!!

Martijn over at the Kodi Forums asked them to move from 15.2 to a nightly which I assume was 16.* or something. But whatever it was, it seems to have fixed the issue with the android platform. Wonder if its the same thing with OSMC/Kodi and 16.*. Here’s one of his replies when asked what the changes were

way of which we push video to the hardware.
It also makes your TV do UHD playback which wasn’t possible on 15.2 version
Other Sony owners have confirmed it working really well.

Please help guys. I really love Kodi man. Been in love with it from the first day I’ve found it.

Ok guys
Some great news. I cracked it. Woohooo!!
Excuse the long post, but I think i got down to the bottom of this.

So basically, what was causing it to go nuts was a combination of the Raspberry Pi 2 and the projector. I think this projector has a strange behavior to automatically do some adjustments to the displayed image if the input resolution is anything other than 1920x1080p at a refresh rate not less than 60Hz. The way I cracked it was by installing Kodi on my laptop and running the same content through. Didnt notice any change in brightness or auto correction of contrast. So i checked my video settings and tried to match what Kodi was setup to and noticed that Kodi was setup to output just 720p @ 50Hz. Swapping that out to 1080p at 59.94 or 60.00 fixes the issue.

One last thing I found happening was setting the Kodi to 1920x1080p @ 60.00Hz automatically changes the resolution to Desktop. Dont know what that means, but I am guessing its fine cause the amp recognises the input signal as 1080p and thats all that matters to the projector to not auto dim/switch.

Thanks again for all the feedback guys. Hopefully this thread helps someone else who may have a similar setup sometime in the future. Cheers

Desktop is the resolution captured from the EDID (or hdmi_mode configured in config.txt). It’s added to @popcornmix’s backports.

It looks like your projector is a 4.3 resolution projector. Does it handle a 1080p signal OK? You can adjust the signal in config.txt.

Pi probably read the EDID change and changed the resolution.

My guess (same with Optoma), is that your projector allows for different brightness / contrast settings based on resolution and Hz. I got caught out with this when I used to run my Xbox 360 on 1080i from the amp and my PC at 1080p and noticed differences in colours. Also got caught out where Adjust refresh rate on would look visually different. Checked the settings, and indeed, the projector settings were different.

If 1080p works well. You can force 1080p60 as an HDMI mode, although not ideal for judder…

@sam_nazarko thanks for replying man.
Yeah, this was a strange one. Luckily I had 2 days time on my hands to figure it out. Trust me, when I saw the difference, I couldnt believe it. I thought everything was same but the auto contrast thingy on the projector was just something that was bugging me and I knew it’d be difficult to understand or explain.
I am sure it happens to others as well. The projector has almost minimal settings. So cant even turn that off as an option. Will write to Sony though.

Its handling the 1080p signal well. One thing I noticed is that when I was on the laptop, the projector firmware gave me additional options to control the image as well which doesnt show up when on the Pi. When i get some more time on my hands, i’ll try and figure out what I need to do on the Pi to get it to show up as well. Any suggestions are welcome.

I just hope someone finds this thread handy. It was so annoying for the last 2 days that I had to register just to post about it. haha.
Thanks for the awesome job with OSMC / Kodi guys. I truely love it.

I’m glad it’s resolved now, albeit to an extent.

Welcome to the forum :slight_smile:

Dear everyone,

i was ever so happy to stumble upon this thread. I am experiencing the exact same problem, i have a Rasp Pi3 with the latest OSMC-version. I run through a Marantz SR6008 onto a Panasonic TXP55 plasma. No other input-source has any kind of automatic dimming and or adjustment. My new little media-player has. I did change all the available settings back and forth to different frequencies and resolutions but the problem persists. :frowning: All known automatic features have been disabled on my side. Any ideas what i could do?

Thank you in any case and best wishes!