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I am working on a project that involves a raspberry pi outputting video to tvs. I'd like to have the raspberry pi always output FullHD video.

If it was booted without a display, by default it switched to composite. By adding force_hdmi_hotplug=1 or something along those lines I got it to always output on HDMI.

However if I power it on without a display, it defaults to a lower resolution (720p?). I could force a specific CEA/DMT mode, but the displays have different refresh rates and progressive/interlaced modes, so I would have to find a mode supported by all.

How would I solve this?

I guess I would have to either:

  • configure it to keep the resolution and find the best mode when a tv is plugged
  • manually poll available modes, try to find the best, and tell to switch to that. How would I change resolution on command line? I have the X server running a single app without a window manager / desktop environment
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  • AFAIK, Raspberry Pi always uses 720p mode, but upscales it to the 1080p if necessary.
    – lenik
    Commented May 14, 2014 at 16:11
  • @lenik, Interesting, I didn't know that. Is there a way to force upscale then? :)
    – varesa
    Commented May 14, 2014 at 17:16
  • rPi does full 1080p, not just upscaled.
    – me--
    Commented May 14, 2014 at 23:34

2 Answers 2

Reset to default
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In the /boot/config.txt file you could try to adjust the framebuffer_width and framebuffer_height settings to 1920x1080, this will force the image at that resolution through the HDMI port.

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I have found that uncommenting the

disable_overscan=1

setting in /boot/config.txt helps if a black border persists.

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  • This answer seems to apply to a problem (black border) that the question doesn't mention.
    – Dmitry Grigoryev
    Commented Mar 6, 2020 at 7:42
  • I agree with you. But... If a black border persists around your screen, does this not mean that the resolution is not 1920x1080? If the image was cropped, I would agree that the resolution might be 1920x1080, but this is not the case.
    – RubenvWyk
    Commented Mar 8, 2020 at 2:34

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