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Full Version: Auto Contrast / Auto Dim
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Hi guys
I know this is my first post here and I must start by thanking you guys for the best possible media player that I've used day in and out for the last 3 odd years.
But I am having the strangest problem.

I started to notice this only after I got myself a new Sony 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

Rasberry Pi with Kodi 16.1
Set-top Box

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 color shifts on the television from any source
  • Cannot see color 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 color shift on television. Color 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.

As a test, does this happen if the Pi is directly connected to the projector?
(2016-06-02, 02:14)Ned Scott Wrote: [ -> ]As a test, does this happen if the Pi is directly connected to the projector?

Yes it does. It's a strange one. I googled this problem and I found one other thread again with a Sony television and the smart tv based kodi. One mod suggested upgrading from their current build to a nightly and the issue apparently went away. The mod mentioned in the thread that it's something to do with how the content is delivered to the hardware.

Wonder if it's something similar.
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