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No picture on smartphone HDMI out

Skaven252
Explorer
I tried to use the Rift devkit as a passive stereoscopic display for my phone for viewing my stereoscopic POV videos (as in, only the display functionality needed, no head tracking or software warping required). The phone is a Nokia 808 PureView that has a HDMI out. The phone has an application called Big Screen which allows you to view videos in full HD or other resolutions via the HDMI out.

Alas, the Rift refuses to display the image from my phone. Rift's display remains black and unlit. This is the case even when the Rift is plugged into the desktop PC's USB (because it also refuses to display anything if the USB is not plugged in). The phone detects that a HDMI display is plugged in, however.

Wondering why the picture does not show up? I tested my phone's HDMI out with my television, and it does work. So the problem is in Rift's end. Unsupported resolution, with no image scaling on either end?

As a general comment, maybe the consumer version could also support functionality as a passive HMD (no USB / head tracking required, just use it for video playback)?
8 REPLIES 8

cybereality
Grand Champion
Sorry, the Rift is only supported on PCs at this time. Thanks.
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Dycus
Honored Guest
The Rift requires that USB be connected to power on, as you noted. If you want to get it to work, you'll either have to connect USB to the phone, or connect together the grounds on your computer and phone. Like Andres said, though, this is unsupported.

Sebbi
Honored Guest
Are you sure guys? Since the Rift is working for me when I plug the USB part into a battery pack and the screen to the HDMI out of either a Nexus 4 or Nexus 10. It also works on Asus Android tablets with HDMI out as long as there is power on USB and the power plug itself.

Skaven252
Explorer
I did try plugging the Rift's USB to a PC and the HDMI to the phone. No picture.

I also bought an adapter and tried plugging both to the phone to see if it gets powered (the phone gave an "Unsupported USB device" error). Still no picture.

USB battery pack sounds like an interesting idea, guess I could try that too (or just a USB wall wart to get a neutral input) - but I'm not optimistic with the results so far.

Maybe the Android devices you've tried, Sebbi, have image scaling built in so they can output the picture in Rift's native resolution, while the Nokia 808 only outputs in 1080p?

Sebbi
Honored Guest
Android devices seem to output 1280x720 resolution, but I've notices the Rift screen scales nearly every resolution to its screen and can even "display" 1080P (since the screen is 1280x800 both resolutions don't have the correct aspect ratio).

Skaven252
Explorer
"Sebbi" wrote:
but I've notices the Rift screen scales nearly every resolution to its screen and can even "display" 1080P (since the screen is 1280x800 both resolutions don't have the correct aspect ratio).

Are you sure it's the Rift doing the scaling, and not the output device?

Because that might be the problem between my Nokia 808's HDMI out and Rift: neither of them scales the image. Maybe.

Sebbi
Honored Guest
You can connect the Rift to your PC and let it mirror a 1080P screen. A blue box on the Rift screen will inform you of the correct 1080P resolution even though the panel is only 800P. I've seen many car monitors doing the same ... they accept any resolution and are advertised as supporting 1080P even though they can't really display it.

Skaven252
Explorer
Good to know. Thanks.

Then I'm mystified as to why my Nokia 808's HDMI out refuses to cooperate with the Rift, even though my 1366 x 768 television shows the picture from the 808 just fine. Is the signal different from a PC HDMI out or something?