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U2413, overscans on the HDMI input, how to disable?
I have hard times trying to control the slight overscan issue I have sending 1080i video from Avid Media Composer with Matrox MXO2 mini to my U2413 via HDMI. The issue is that the image is clearly somewhat cropped on each side (and yes, only 1920x1080 pixels are used on the 1920x1200 monitor, as expected). I could not find a setting to enable/disable overscan in the U2413 (or force 1:1 pixel mapping, as should be the default with this standard 1080i or 1080p video). Usually when there is an overscan/underscan issue, it is the monitor that is the culprit, and most monitors allow to choose between overscan or 1:1 pixel mapping (the latter avoids artifacts and distortion due to picture scaling). Am I missing something?
DELL-Chris M
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August 29th, 2014 23:00
Displays engineering sent this to me today =
This overscan presented by you for 1080i video timing is part of a Dell requirement for all interlace modes and cannot be changed.
DELL-Chris M
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August 4th, 2014 11:00
The only options that the U2413 has in its Menu is Display Settings -Aspect Ratio (16:10, 16:9, Auto Resize, 4:3, 1:1). See page 34 in the online U2413 User's Guide.
Overscan/underscan issues are usually the fault of the video card settings, not the monitor. For example, the AMD Ati Catalyst scaling default is set to around 7.5 which causes a thick black border around all four sides of the display. Nvidia also has its own scaling options.
benoitm
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August 26th, 2014 14:00
Thanks for your reply.
Following this info and Matrox's statement about their device always outputting 1:1 signal, I did some more tests, and found puzzling results:
When working on a 1080/25p (progressive) project, absolutely no overscan occurs: the full 1920x1080 square pixels are displayed in 1:1 fashion; there is no geometric distortion nor artefacts.
Things become strange when working with a 1080/50i (interlaced) project !
If the U2413 is set to "Wide 16:9" AR, the aspect ratio is preserved, but the image is slightly zoomed in and cropped to fit in the 1920x1080 pixels of the (expected) target area (about 1...1.5% overscan), meaning there is some vertical + horizontal resolution loss and scaling artefacts.
If instead the U2413 is set to 1:1 pixel mapping, the same cropping exists, but the 1:1 pixel mapping happens ONLY in the vertical direction: about 98% of 1080 horizontal lines are 1:1 mapped to the same number of vertical display pixels; horizontally, nothing changes: the image is horizontally enlarged, then cropped to fit 1920 pixels. The net result is: there are no scaling artefacts vertically, but there are still horizontally AND the display aspect ratio is no longer correct, it is now closer to 1.85 (instead of 1.78).
So my point is: with interlaced video (e.g. 1080/50i) there is no way to have true 1:1 mapping AND correct aspect ratio on the U2413 !
benoitm
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September 5th, 2014 06:00
Very unfortunate that this is nowhere documented (product spec sheets or user documentation). I lost quite a few hours experimenting and trying to figure out what was happening and who is the culprit (Avid, Matrox, Dell)
benoitm
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September 8th, 2014 00:00
Thinking more of it, I find this requirement awkward, especially when the user forces 1:1 mapping in the menu...