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raspberrypi / picamera2

New libcamera based python library
BSD 2-Clause "Simplified" License
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[HOW-TO] DRM preview in fullscreen #1041

Open ArosPrince opened 4 months ago

ArosPrince commented 4 months ago

Hi, I am trying display a video feed on Pi OS Lite using the DRM preview. I want it to be fullscreen. By default though it creates a small frame in the top left of the screen. Looking at the default params of the start_preview I assume it's 640 x 480.

Now obviously I could hard-code the screen size, something like picam2a.start_preview(Preview.DRM, x = 0, y = 0, width = 3840, height = 2160) or import drm and query the screen size. But it would be really surprising if there was no standard way of doing it.

There has to be a built in Picamera2 param to enable this, right?

Thanks!

davidplowman commented 4 months ago

Hi, I'm afraid I don't really know too much about that. I'm guessing the standard way might be to import drm and query that? Alternatively, asking on one of the more general, or perhaps graphics, forums might lead you to folks with more knowledge in this area. Sorry not to be more help!

ArosPrince commented 4 months ago

Hi, basically what I'm asking is if there's a standard way to do it and from what you write it looks there isn't.

The C++ implementation has a --fullscreen param. When creating the preview it calls drmModeGetCrtc to get the screen dimensions and if fullscreen is on, then it uses that for the preview size. I am looking for the same feature here in the Python implementation.

If there isn't one, I can sure use drm to figure it out myself.

davidplowman commented 4 months ago

Once you've started the DRM preview, you can get hold of these values

picam2._preview.crtc.mode.hdisplay
picam2._preview.crtc.mode.vdisplay

which might be the numbers you want, but I wouldn't know if that's just a hack and there's some "official" API to get them!