Titanium 2048x1440
David Pitt (3386) 1248 posts |
I acquired an AOC 2560×1440 monitor at a very advantageous price, free, from a relative who probably thought the offer would be declined. The Titanium’s maximum screen size per DVI port is 2048×2048 so its best 16:9 is 2048×1152. The OAC upscales this resolution, the rendition is quite good but not as crisp as a native resolution. It seemed like a better solution would be 2048×1440 (4:3). The AOC does pillar box other 4:3 resolutions, but not 2048×1440 which it insists on stretching to fill the 16:9 screen. Oddly Ubuntu does display in 2048×1440 as a 4:3 pillar box but that is a different input, display port whereas the Titanium is DVI. The next bright idea was to fit the 2048×1440 display into a 2560×1440 MDF entry by padding the horizontal blanking timings. # 2048 x 1440 # 2560 x 1440 (60.00Hz) INT RBlank 32bit (CVT) startmode mode_name: 2048 x 1440 x_res:2048 y_res:1440 pixel_rate:121000 h_timings:32,80,256,2048,256,48 v_timings:5,13,0,1440,0,3 sync_pol:3 endmode (Reduced blanking and interlace are need with this monitor to avoid horizontal jitter on larger modes.) That mode displays perfectly, a nice crisp native display. There is a bit of a but though. The snag is that the pointer with not move beyond 2" in from the right hand desktop edge. It goes all the way to the left hand edge and stops there. The mouse bounding box does not coincide with the displayed desktop. It looks as if the right hand edge of the mouse bounding box is 2048 from the start of the line and not 2048 from the start of the desktop, that is it stops in the desktop at 2048-256. It is only the display of the pointer itself that is bounded, a drag outline will continue all the way to the right hand edge. A workaround is to shift the display to the left hand edge of the screen and move all the padding to the right. # 2048 x 1440 # 2560 x 1440 (60.00Hz) INT RBlank 32bit (CVT) startmode mode_name: 2048 x 1440 left x_res:2048 y_res:1440 pixel_rate:121000 h_timings:32,80,0,2048,512,48 v_timings:5,13,0,1440,0,3 sync_pol:3 endmode This works but does look a bit odd, centre’d is nicer. If memory serves, unlikely, there was a similar issue with the Pi, now fixed, my RPi3 is fine at 2560×1440. |
andym (447) 464 posts |
I have a Titanium and the same monitor, just not connected together. Have you tried the controls on the actual monitor to see if that will enable a proper pillar box mode – I’m sure there’s an Auto setting on there to force the monitor to reset itself. Another option would be to try a DVI to HDMI adaptor and connect in to the HDMI port on the monitor? Don’t make the initial mistake I made and think a DVI to Display Port adaptor will help, unless you’re prepared to fork out for one of the £45ish active ones. The £6 ones work the other way only. Like you say, I seem to remember a similar issue with the Raspberry Pi, long since fixed, but I can’t remember the solution. Something to do with software vs hardware pointers? |
David Pitt (3386) 1248 posts |
Specifically the monitor model is AOC Q2770PQU. ‘Auto’ and ‘4:3’ settings in Menu are unhelpfully greyed out with a 1920×1440 input. I did discover that 1600×1200 which does default to 4:3 could rather uselessly be switched to widescreen and stretched, the converse of what is required. There is a 4:3/Widescreen hot switch on some versions of the monitor but not on the one I have.
That didn’t work either. The primary purpose of the monitor is as a second screen for an iMac. |
Jeffrey Lee (213) 6046 posts |
Correct. The problem here is that when TI updated the chip to support 4K resolutions, they forgot to update the overlay hardware. So you can drive a 4K resolution, but the overlays are still limited to 2K size & (top-left) coordinates up to 2K. So you can have a 2560×1440 signal with a 2048×1440 overlay for the desktop at 256,0 and have it display just fine, because the overlay size & position values are <=2K. But the mouse overlay needs to move around the screen, so if your desktop extends beyond the 2K limit then at some point the mouse is going to hit the 2K coordinate limit and the hardware won’t be able to render it. The solution is for the driver to either add padding to the image (which could get really nasty with 4Kx4K) or switch to a software pointer – neither of which is happening, from the sound of things. If the Titanium were to provide a HDMI signal to the display it may be able to request that the monitor displays your original 2048×1440 mode in a 4:3 aspect ratio – but I’m not sure whether the AOC monitors pay attention to the aspect ratio field. (perhaps they do, if Display Port is working? I’d assume Display Port supports similar metadata to HDMI) |