PC to Veon help

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Beaker03

6 posts

Wannabe Geek

#207593 4-Jan-2017 14:11

Hi all,

I recently purchased a 43inch Veon 4k TV to use as a monitor on my HTPC. I'm really happy with the picture and as I've got external speakers I'm not worried about the onboard sound, which I believe is very poor. The TV is working perfectly except for one small issue, which I can happily live with if need be, but I'm hoping someone might have a fix.

The HTPC is running a GTX750ti and when I first plugged the screen in using HDMI the picture had a really strong pink/purple tinge to it. After playing with various settings I managed to fix the issue by adjusting the refresh rate of the 750ti to 50mhz from what was 60mhz. Everything works perfectly until I restart the HTPC, then the pink tinge comes back. I go back into the graphic card settings and it's still at 50mhz as I'd set it previously. This time I adjust it back up to 60mhz and all is good again, until I restart the PC again and I'm back at square one having to adjust back down to 50mhz. I'm basically going up and down, back and forth from 50 - 60mhz every time the PC restarts. It doesn't matter which one I select, as long as it's a change from the previous setting, and it seems to fix the issue. I've very confused as to why it's happening.

In all reality the PC only gets powered down once a week or so, so it's not a problem, except if I'm not at home and my other half starts playing around with settings. God help me if that happens! Anyone have any idea's, apart from getting rid of my wife, which does seem a little drastic.

gbwelly

1263 posts

Uber Geek
+1 received by user: 776

#1698364 4-Jan-2017 14:33

Sounds like you need to buy a bottle of the purest Green, and put a couple of drops of it in your HDMI cable. Or perhaps try a different HDMI cable which may have more green in it already.

tangerz

662 posts

Ultimate Geek
+1 received by user: 199

#1712703 30-Jan-2017 12:27

OK, I'm pretty sure this has to do with the kind of colour signal being output by your graphics card.

As I understand it, by default PCs (graphics cards, actual monitors etc) use an RGB colour signal. By default, TVs and other AV equipment (Blu-ray players, STBs etc) use a YCbCr colour signal. (I say by default because I'm pretty sure they all can use both, just that they default to a certain one.) For an HDMI connection, which of these signals to use is generally worked out during the HDMI 'handshake' and it would seem this is where your system is falling down. ie the colour signal to use isn't being negotiated properly.

When you have been going in and changing the refresh rate for your graphics card, this has been forcing the HDMI connection to 'handshake' again and the correct colour signal is negotiated... until you reboot the PC, and the proper colour signal negotiation is lost.

Instead of going into the settings and changing the refresh rate, it should be possible to force an HDMI 'handshake' by simply turning the TV off and back on (while the PC is running) That should work, but if it doesn't, there is a more permanent solution anyway.

Go into your graphics card settings and find the colour signal the PC is outputting. If you can change this setting to YCbCr and save it, you should be all good. Now on startup, the PC is outputting YCbCr (instead of defaulting to RGB) which is what the TV is expecting (as it defaults to YCbCr colour signal)

It may be possible to do the reverse and set the TV to expect an RGB colour signal but this is less likely as it depends on the TV settings available (and most don't have it!)

Hope this helps, ( ...and then you don't need to trade-in the wife! )

richms

29098 posts

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#1712712 30-Jan-2017 12:41

Mismatch of the colorspaces and video levels is also why PC playback on a TV is often very banded on graidents since things are being converted all over the place to different formats at the absurdly low 8 bit depth that video has traditionally used.

In the nvidia stuff on my gaming PC I had to try all the options to get one that didnt completly kill all the black detail (and highlights too) which was RGB and limited. Anything else and all the black detail was just gone. The conversion on the PC doesnt seem to add dither to it so its quite noticiably banded on sky and similar things in game, but better than not seeing anything in the dark.

Proper TVs will let you choose a full range input which will solve that problem, and also not screw up deciding if it is YUV or RGB. If you are outputting RGB then watch that you dont output 422, that will really make things look like crap for text etc as the colour is at a lower resolution to the native resoultion, so things like white text on green and similar common things in windows become aweful to look at.

Richard rich.ms