I just got myself a new screen, an iiyama XB2483HSU-B3 connected over HDMI. When I plugged it in, I was very surprised to see a grey background that is supposed to be black since it's supposed to have a 3000:1 contrast ratio. I tried to change the default refresh rate from 60 to 75 and then I actually got black. After some digging, I found that it might be related to the "Broadcast RGB" property. The output from xrandr --prop by default is: HDMI-3 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 527mm x 296mm _ICC_PROFILE: 0 0 14 148 97 114 103 108 2 32 0 0 109 110 116 114 82 71 66 32 88 89 90 32 7 226 0 2 0 15 0 22 0 35 0 24 97 99 115 112 42 110 105 120 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 246 214 0 1 0 0 0 0 211 45 97 114 103 108 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 100 101 115 99 0 0 1 32 0 0 0 101 99 112 114 116 0 0 1 136 0 0 0 47 108 117 109 105 0 0 1 184 0 0 0 20 119 116 112 116 0 0 1 204 0 0 0 20 98 107 112 116 0 0 1 224 0 0 0 20 118 99 103 116 0 0 1 244 0 0 6 18 114 88 89 90 0 0 8 8 0 0 0 20 103 88 89 90 0 0 8 28 0 0 0 20 98 88 89 90 0 0 8 48 0 0 0 20 114 84 82 67 0 0 8 68 0 0 2 12 103 84 82 67 0 0 10 80 0 0 2 12 98 84 82 67 0 0 12 92 0 0 2 12 97 114 116 115 0 0 14 104 0 0 0 44 100 101 115 99 0 0 0 0 0 0 0 11 105 105 121 97 109 97 46 105 99 99 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 116 101 120 116 0 0 0 0 EDID: 00ffffffffffff0026cd2861b6080000 321b010380351e782aa1a5a755529f27 125054a56b80710081408180a940b300 9500d1c00101023a801871382d40582c 45000f282100001e000000ff00313135 36343735303232323330000000fd0037 4c1e5312000a202020202020000000fc 0058323438332f323438310a20200176 020322f14f9005040302011112131406 0715161f230907018301000065030c00 1000023a801871382d40582c45000f28 2100001f011d80d0721c1620102c2580 0f282100009e011d00bc52d01e20b828 55400f282100001e2a4480a070382740 302035000f282100001a023a80d07238 2d40102c45800f282100001e00000017 aspect ratio: Automatic supported: Automatic, 4:3, 16:9 Broadcast RGB: Automatic supported: Automatic, Full, Limited 16:235 audio: auto supported: force-dvi, off, auto, on link-status: Good supported: Good, Bad 1920x1080 60.00*+ 74.97 50.00 59.94 1920x1080i 60.00 50.00 59.94 1600x1200 60.00 1680x1050 59.88 1280x1024 75.02 60.02 1440x900 59.90 1280x960 60.00 1152x864 75.00 1280x720 60.00 50.00 59.94 1152x720 59.97 1024x768 75.03 60.00 832x624 74.55 800x600 75.00 60.32 720x576 50.00 720x576i 50.00 720x480 60.00 59.94 720x480i 60.00 59.94 640x480 75.00 60.00 59.94 720x400 70.08 But if I do this: xrandr --output HDMI-3 --set "Broadcast RGB" "Full" The black becomes black. So it seems that by default it's doing "Limited 16:235" for some reason. The only other way I could get proper black was using 1920x1080@75. I'm running Debian's 4.14.13-1 kernel. I have an intel i5-2500
HDMI 1.4a section 6.6 Video Quantization Ranges: Black and white levels for video components shall be either "Full Range" or "Limited Range." Limited Range shall be used for all video formats defined in CEA-861-D, with the exception of VGA (640x480) format, which requires Full Range. CEA-861-D section 4.15 1920x1080p @ 59.94/60Hz (Format 16). (CEA-861-D does not define the format at 75 Hz.)
So you're saying this is actually a problem with the monitor, and it should have been expecting Limited 16:235 by default? But then I haven't seen any monitor that has an option to set that.
Are we ok to close this ?
Closing, please re-open if still occurs.
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