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raspberrypi / userland

Source code for ARM side libraries for interfacing to Raspberry Pi GPU.
BSD 3-Clause "New" or "Revised" License
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raspicam: Add -dn option to set the display number #572

Closed 6by9 closed 5 years ago

6by9 commented 5 years ago

Allows options like -dn 7 to push the preview onto HDMI1.

pelwell commented 5 years ago

How does -dn 7 result in output on HDMI1? What are the legal display numbers?

6by9 commented 5 years ago

Takes the standard Dispmanx display enums - https://github.com/raspberrypi/userland/blob/master/interface/vmcs_host/vc_dispmanx_types.h#L58

pelwell commented 5 years ago

I predict confusion. At the very least the usage info should say that, but perhaps a string would be more user friendly.

popcornmix commented 5 years ago

We do use the same numbering in other places (tvservice, omxplayer) Although tvservice does help you work it out.

pi@b3plus:~ $ tvservice --help
Usage: tvservice [OPTION]...
...
  -l, --list                        List all attached devices
  -v, --device                      Specify the device to use (see --list)
pi@b3plus:~ $ tvservice --list
2 attached device(s), display ID's are : 
Display Number 2, type HDMI 0
Display Number 7, type HDMI 1

Not sure if a simple string could explain it.

6by9 commented 5 years ago

Perhaps a string is nicer, although still not totally unambiguous (see below).

It's the same numbers as have been previously used with omxplayer https://www.raspberrypi.org/documentation/raspbian/applications/omxplayer.md

If you are using the Raspberry Pi Foundation's touchscreen display, and you want to use it for video output, use the display option to specify which display to use. n is 5 for HDMI, 4 for the touchscreen. With the Raspberry Pi 4 you have two options for HDMI output. n is 2 for HDMI0 and 7 for HDMI1.

omxplayer --display n /opt/vc/src/hello_pi/hello_video/test.h264

Dispmanx display numbers is a mess anyway. The numbers get remapped if the display specified doesn't exist, so 0 (nominally MAIN LCD) will go to HDMI0 if neither a DSI or DPI display is connected.

pelwell commented 5 years ago

I'd settle for a reference to dispmanx numbering or tvservice --list.

6by9 commented 5 years ago

Help text string and commit text updated.

pelwell commented 5 years ago

Thanks - looks good to me.