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Joined: Fri Apr 13, 2018 5:13 pm
Location: East Moline, IL

HDMI and screen size

Sun Apr 22, 2018 10:28 pm

So far I’ve used my 3B+ on two televisions, ones a 32 inch and another is a 40 inch one.
On my personal tv(the 32” one), I can easily change a few settings so the picture fits the tv perfectly. But on my grandmas(40”), the picture doesn’t quite fit, and I have to use an odd resolution in order for it to fit.
Is there a setting somewhere that I’m maybe overlooking in any of the display settings? I’d like to make it easy for me to see on both televisions so I don’t have to squint.

(Also I did recently discover the OpenGL video driver settings, and although it solves this issue to a degree, it doesn’t play nice with the official 7” touchscreen. It also makes some of the text and colors look a bit odd on screen. I understand that this is still undergoing development and is experimental)

W. H. Heydt
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Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: HDMI and screen size

Mon Apr 23, 2018 4:48 am

The size of the screen is irrelevant. What matters is the resolution, and more specifically, the resolution that is actually displayed. Your issue may be why the "overscan" parameters exist.

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Location: Aloha, Oregon USA

Re: HDMI and screen size

Mon Apr 23, 2018 8:49 am

One difference between a computer monitor and an HD TV is that a television will not show the entire picture. Televisions overscan by default, which means the picture is larger than the display area and the edges are cut off. Some televisions can enable or disable overscan in their settings, but they usually don't call the setting overscan (that would be too easy), and each manufacturer has their own name for it, so it may take some digging to find it.

Note that Raspbian also has an overscan compensation setting in config.txt which you can change with raspi-config or the GUI configuration utility. So ideally you want to disable overscan in both your TV and Raspbian, and then have your Pi output the native resolution of the screen (which normally happens automatically).

In my experience Full HD 1080p sets usually have the ability to disable overscan, but many 720p/768p sets do not. However, there may be one input that is designated for a computer, and that input should have overscan off by default. Sometimes that PC port will be obvious because it will be VGA or DVI, but on more recent sets it's usually one of the HDMI inputs.
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