omxplayer output to USB DisplayLink?


7 posts
by siomiz » Tue Nov 06, 2012 11:47 pm
Hi,

On Raspbian, is it possible to direct omxplayer's output to USB DisplayLink monitor (/dev/fb1) ?

I followed a walk-through at http://anup.info/blog/2012/10/13/raspberry-pi-mimo-monitor to bring up X
on my MIMO UM-710S (http://amzn.com/B002RMPASG), which is working great.
But omxplayer output always goes to HDMI/TV and omxplayer doesn't seem to have any option...

Or rather, is there a way to make the USB monitor the primary output that can be used without starting X?
Right now I only see the green screen until X comes up.

Thanks!
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by hunternet93 » Fri Nov 09, 2012 7:48 pm
I believe that omxplayer only works with the Pi's internal graphics chip, USB monitors have their own GPUs. You could use mplayer or another video player instead, with proper file conversion you should be able to play video smoothly.
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by siomiz » Sat Nov 10, 2012 6:16 am
Hmm. I somehow believed that the DisplayLink's chip on the screen side is only responsible
for decoding transferred data to the bitmap so the Pi's GPU acceleration would be possible here... :oops:

Anyways, I will try mplayer (and VLC maybe?) and find out optimal bit-rates for smooth playbacks.

Thanks hunternet93!
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by ghans » Sat Nov 10, 2012 8:58 am
As mplayer and VLC struggle even with SD resolutions (only 8 fps or so) ,
you'll be dissapointed. Hardware acceleration is the achilles heel of the Pi.


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by hunternet93 » Sat Nov 10, 2012 12:52 pm
Disclaimer: I could be completely wrong, there may be a way to use the GPU with a USB screen. Apparently that's how it works on desktop computers, according to http://www.displaylink.com/technology/technology_overview.php. I'm not sure if it'll work with the Pi or not, but it's possible.
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by ghans » Sat Nov 10, 2012 2:38 pm
But on Linux i'm sure that'll need some serious X Server hacking first.


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by siomiz » Tue Nov 13, 2012 5:45 am
Thanks ghans.

I see GPU acceleration is a must for video playback on Pi... :?

I have found a project that just might do the trick: http://www.directfb.org/
(since the display is already assigned /dev/fb1 thanks to the kernel module, I think it's just a matter of utilizing that framebuffer.)
so I'm playing with it...
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