adammw
Posts: 21
Joined: Fri Jun 15, 2012 4:28 am

Tool to swap displays HDMI<->SDTV

Sat Jun 16, 2012 10:31 am

Hi, I was looking for a way of easily doing this, but the bundled tvservice binary didn't seem to support SDTV, so I went looking for how to do it with the vc_tvservice APIs. I don't really understand them, but I seem to have got something that works and I thought I would share them here: https://github.com/adammw/rpi-output-swapper
Hopefully I haven't wasted my time as something else already exists that does this simpler, but at least I know a bit more about the system.

The major part of getting this to work is knowing how to initialise the APIs so they don't throw you back error codes instead of working, which is definitely not helped by the lack of overall documentation of how to use them.

Not sure if it works with an X environment (I don't use it so I don't know), but it automatically calls fbset so if your in a console it will appear on the new screen, and I've tested it to work fine with even omxplayer still running.

Thanks.

User avatar
rew
Posts: 408
Joined: Fri Aug 26, 2011 3:25 pm

Re: Tool to swap displays HDMI<->SDTV

Sun Jun 17, 2012 7:58 am

Hey Adam,

with your newly aquired knowledge: Do you think I might be able to configure a 320x240 framebuffer that would display using standard composite video? Or is the composite video framebuffer always one of the standard sizes?
(I have a composite input 320x240 display. Now the display downscales the incoming video to display it. The console text becomes barely readable at three pixels high.... )
Check out our raspberry pi addons: http://www.bitwizard.nl/shop/

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5100
Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: Tool to swap displays HDMI<->SDTV

Sun Jun 17, 2012 9:27 am

@rew
Doesn't:
framebuffer_width=320
framebuffer_height=240
in config.txt do what you want?

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