How to set correct dynamic (rgb) range

[Mencius]

Hi all

I would like to know how to correctly set the dynamic (RGB) range to use my TV with the steam link. Currently the colors don't look quite right (a little washed out).

I am using an LG B7 which is (I believe) capable of full (0 - 255) RGB 4:4:4 when set to PC mode but of course it can also do limited (16 - 235) RGB.

I have read everything that I can find about this and I'm confused. I have read comments that the steam link can only do limited RGB and I have read comments that the developers have implied that, if your TV can accept full dynamic (rgb) range (something to do with the EDID), then the link will send full range.

Indeed, when I set the LG B7 to "PC" mode and set RGB range to "Auto" on the TV, the TV defaults to full range RGB which would suggest that the TV thinks the link is sending full range!

And yet the picture doesn't look quite right but then I'm not sure it looks right when set to limited either....

I have read suggestions that changing the RGB range of the video output in the nvidia control panel may do something but I couldn't see a difference.

Can anyone provide me with some advice?

[Destado1]

For a TV is needs to be YCbCr 4:4:4

EDIT: https://pcmonitors.info/articles/correcting-hdmi-colour-on-nvidia-and-amd-gpus/

[Mencius]

What needs to be? And does the steam link even output that anyway?

Not sure it would matter anyway since RTINGS say that the LG B7 is agnostic as to whether the input is YCbCr 4:4:4 or RGB input:

"4:4:4 sampling can be achieved while sending an RGB signal instead of YCbPr444. The TV will accept both, but will only show a proper 4:4:4 image if the PC icon is used. Otherwise, it will not reproduce the image perfectly and it results in text looking closer to a 4:2:2 signal."

https://www.rtings.com/tv/reviews/lg/b7-b7a-oled/settings

[Destado1]

Yes, the Steam Link will get a proper signal I have a 27" LCD as my main screen using HDMI, which YCbCr is optimal. On my TV it looks as it should. The one thing I had to turn off is GPU scaling in the Radeon settings to get the image to not be clipped at the edges.

[Destado1]

Sorry should have been clear. Your GPU settings should have options like RGB 444, RGB 422, YCbCr 444. YCbCr 422. Maybe other options as well.

[Xjph]

According to the devs the Link follows the HDMI spec on this one, which is unfortunate, because in a nutshell the spec says "always send limited range unless the TV reports that it can be configured via HDMI to do otherwise."

People have been asking for manual control of this for a while, but it hasn't shown up.

[Mencius]

Originally posted by Destado1:

Sorry should have been clear. Your GPU settings should have options like RGB 444, RGB 422, YCbCr 444. YCbCr 422. Maybe other options as well.

Ahh yes, I see what you mean.

Does changing that option make a difference for the steam link though? I have read other comments saying that the GPU driver output setting does not effect the steam link or any other video capture application.

I did experiment with setting full range RGB output in the driver and I couldn't see a difference on the TV.

[Mencius]

Originally posted by Vithigar:

According to the devs the Link follows the HDMI spec on this one, which is unfortunate, because in a nutshell the spec says "always send limited range unless the TV reports that it can be configured via HDMI to do otherwise."

People have been asking for manual control of this for a while, but it hasn't shown up.

Thanks for that info. Manual control would definitely be helpful!

Do you know if there's a way to tell from the performance info, the debug logs, or anywhere else what signal the steam link has negotiated with the TV (whether full or limited)?

If I can be certain that the link is sending either full or limited then I can set the correct setting on the TV, be comfortable that I have nothing misconfigured, and then the picture just is what it is.

As mentioned, at the moment when I set the RGB range on the TV to auto it defaults to full range RGB which suggests it might be sending full but I can't be sure...

[Mencius]

To update, I grabbed the EDID from the steam link debug logs (I think) and it variously reads "Display Type: RGB 4:4:4 + YCrCb 4:4:4", "Supports YCbCr 4:4:4 Deep Color", and "Quantization Range selectable via AVI Q for RGB formats".

I think one or the other of these indicates that my TV is advertising that it supports full range hdmi but that's as far as my limited knowledge (and intelligence) gets me.

Here's the EDID:

0x00 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0x00 0x1E 0x6D 0x01 0x00 0x01 0x01 0x01 0x01 0x01 0x1B 0x01 0x03 0x80 0xA0 0x5A 0x78 0x0A 0xEE 0x91 0xA3 0x54 0x4C 0x99 0x26 0x0F 0x50 0x54 0xA1 0x08 0x00 0x31 0x40 0x45 0x40 0x61 0x40 0x71 0x40 0x81 0x80 0x01 0x01 0x01 0x01 0x01 0x01 0x08 0xE8 0x00 0x30 0xF2 0x70 0x5A 0x80 0xB0 0x58 0x8A 0x00 0x40 0x84 0x63 0x00 0x00 0x1E 0x02 0x3A 0x80 0x18 0x71 0x38 0x2D 0x40 0x58 0x2C 0x45 0x00 0x40 0x84 0x63 0x00 0x00 0x1E 0x00 0x00 0x00 0xFD 0x00 0x3A 0x79 0x1E 0x88 0x3C 0x00 0x0A 0x20 0x20 0x20 0x20 0x20 0x20 0x00 0x00 0x00 0xFC 0x00 0x4C 0x47 0x20 0x54 0x56 0x0A 0x20 0x20 0x20 0x20 0x20 0x20 0x20 0x01 0x63 0x02 0x03 0x60 0xF1 0x5A 0x61 0x60 0x10 0x1F 0x66 0x65 0x04 0x13 0x05 0x14 0x03 0x02 0x12 0x20 0x21 0x22 0x15 0x01 0x5D 0x5E 0x5F 0x62 0x63 0x64 0x3F 0x40 0x2F 0x09 0x57 0x07 0x15 0x07 0x50 0x57 0x07 0x01 0x3D 0x06 0xC0 0x67 0x04 0x03 0x6E 0x03 0x0C 0x00 0x20 0x00 0xB8 0x3C 0x20 0x00 0x80 0x01 0x02 0x03 0x04 0x67 0xD8 0x5D 0xC4 0x01 0x78 0x80 0x03 0xE2 0x00 0xCF 0xE3 0x05 0xC0 0x00 0xE3 0x06 0x0D 0x01 0xE2 0x0F 0x33 0xEB 0x01 0x46 0xD0 0x00 0x26 0x0A 0x09 0x75 0x80 0x5B 0x6C 0x66 0x21 0x50 0xB0 0x51 0x00 0x1B 0x30 0x40 0x70 0x36 0x00 0x40 0x84 0x63 0x00 0x00 0x1E 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0xF1

http://www.edidreader.com/

Some possibly relevant/irrelevant background in the links below:

https://steamcommunity.com/app/353380/discussions/0/133259855833824338/

http://blog.toonormal.com/2014/01/10/4k-hdmi-and-deep-color/

[JlnPrssnr]

Bump, because this really should be supported

[iXtremeFROST]

Manually adjust the color output in the settings. Indeed, on a Steam TV, the color range is limited. The image seems to be too bright and not contrast. As if using YCbCr 4: 2: 2 instead of 4: 4: 4. And it would not be bad if it was still possible to choose RGB.

[dimedrol]

Everybody says that steam link or remote play elevated brightness is caused by limited RGB output to HDMI. Yet if I choose limited RGB on the client PC and TV, it changes nothing: games still look washed out a bit. Basically for the washed out colors problem changing client RGB output to limited (to match the supposed steam link setting) does nothing.