Can the Pyra support stereoscopic 3D over the HDMI port?


Good question. It seems HDMI1.4 defines a number of 3d formats, but I don't know if the OMAP5 supports all of them (though on balance it might explain some of the weird wide resolutions it claims to support). Hopefully one of these will match what the Glyph is using.

But like everything else, this depends on someone writing the software to do it, and I'd suggest only a subset of Pyra users are likely to want a 3d headset of any sort, so there might not be a massive market for this work. It should work with 3D TVs too though, which perhaps more people are likely to own these days.
 
EDIT: Okay 3D as in the fake blurry kind not 3D acceleration....

carry on...
 
Yes, I was a little confused by that at first (as well as the name of the product being Glyph, leading to all sorts of other incorrect interpretations), but I'm pretty sure we're talking about stereoscopic 3d here.
 
Title edited to clarify.

I figure with the Pyra's massive storage capabilities, movie watchers on the go might find it attractive, but the screen too small. Something like the Glyph - which has no internal computing and acts as an HDMI connected monitor and coincidentally also runs at 720p - could be the right device to pair with a Pyra for mobile movie viewing. That the Glyph now works on a 3D signal and the head tracking works as mouse - again, kind of a neat pairing.

I've toyed with the idea of getting a Glyph, but wanted to wait on that kind of toy purchase until I have something to actually plug it into - which would be the Pyra. 3D movies through it would be kind of cool - but would the Pyra be able to hold 720p video playback over HDMI at the requisite alternating 60fps?
 
The screen res isn't that critical - we know the HDMI out can run video at 1080p just fine (can't recall what codecs just now), but yeah it might make working with it a bit easier if you can set up first on the internal screen then just copy that to the external. But I think the screen rotator chip can also do scaling, so you can be rendering to 1080p internally and it's scale that to the screen too.

Reading wiki, 3D on HDMI 1.4 is incredibly flexible, so depending on the device we might need to support side by side 720p, double height 720p or alternating frames, depending on what it expects. Trashy's read the docs, he'll be able to tell us which of those are even feasible according to what the OMAP5 can output.
 
From a content perspective, the following functionalities are now integrated:

  • Plug-and-play 3D with HDMI 1.4 compliant, frame-packed, 720p sources
  • Head tracking will now be enabled on all hardware. Press and hold the bottom left button in video mode with USB plugged in to turn on head tracking.
Click to expand...

Code: 
https://www.kickstarter.com/projects/avegantglyph/a-mobile-personal-theater-with-built-in-premium-au/posts/1590772
Maybe that will help?

Are there any Linux video players that can do 3D? Will VLC do it?
 
It dosnt say if it supports manual 3D modes, but 3D TVs always do as far as I know, with manual 3D mode support on the display you simply render your game normally first with one eye on one half of the screen then the other eyes perspective on the other half of the screen, either side by side or above and below, then the display will sort it out and make it 3D depending on what tech the TV itself have like passive or active glasses.
You cant get full resolution automatic 3D mode like the Playstation or Blu-ray player, it requires the proper buffers from the GPU and considering no consumer desktop GPUs have it I doubt any portable GPUs have it either. I dont know what you might need to do to activate the 3D if you have a GPU with full buffers support, mayby its available some command to set in openGL? But without those buffers you have to settle for half resolution 3D like I described, then theres the question if the Glyph has special optics or if it handles the perspective transformation automatically in hardware or something, otherwise you might need the proper perspective matrix data, you might be able to figure it out by yourself there might be guides for how to create such fishbowl perspective, if its needed and not supplied by the company.
 
That's a good point. Rectilinear lenses which are powerful enough to focus on your retina would be stupidly expensive - you're talking many thousand pounds for conventional camera systems which have much more space to play with inside the camera, so the lenses will almost certainly be fisheye at best, or a random set of perspective distortions and colour distortions most likely. If it's got no software inside then the Pyra will need to reverse that distortion.

But apparently is has Android and iOS drivers, so it can't be too taxing to do.
 
HDMI 1.4 defines several stereoscopic 3D formats including field alternative (interlaced), frame packing (a full resolution top-bottom format), line alternative full, side-by-side half, side-by-side full, 2D + depth, and 2D + depth + graphics + graphics depth (WOWvx),[64][101][102] with additional top/bottom formats added in version 1.4a. HDMI 1.4 requires that 3D displays implement the frame packing 3D format at either 720p50 and 1080p24 or 720p60 and 1080p24
Click to expand...

http://www.spectracal.com/downloads/files/Website/Website Articles/Stereoscopic 3D Video in the Home.pdf

found an explanation of frame packing.....
 
mjohansson said:
You cant get full resolution automatic 3D mode like the Playstation or Blu-ray player, it requires the proper buffers from the GPU and considering no consumer desktop GPUs have it I doubt any portable GPUs have it either.
Click to expand...
What blood magic are you talking about?
 
Quad buffer I think its called, front and back - left and right buffers.

https://www.google.se/webhp?hl=sv#hl=sv&q=quad+buffer+gpu


Heres a description : https://en.wikipedia.org/wiki/Multiple_buffering

But thats for full resolution 3D, you can still render both views in same image and use a 3D displays manual mode, but then ofcourse you only get the half display resolution per eye effectivly.

"
Quad buffering
The term "Quad buffering" is used in stereoscopic implementations, and means the use of double buffering for each of the left and right eye images, thus four buffers total. The command to swap or copy the buffer typically applies to both pairs at once. If triple buffering was used then there would be six buffers.

Quad buffering is a technology for implementing stereoscopic frame rendering in computer graphics. For stereoscopic rendering, each eye must receive a separate image. Quad buffering uses double buffering with a front buffer and back buffer for each eye, totaling four buffers.

Similarly to the v-sync in 2D mode, quad buffering allows to swap the front and back buffers for both eyes in sync, allowing the display to seamlessly work with different rendering frame rates.

Quad buffering requires special support in the graphics card drivers which is disabled for most consumer cards. AMD's Radeon HD 6000 Series and newer support it [1].

3D standards like OpenGL[2] and Direct3D support quad buffering."
 
Does video playback usually use double buffering?

I don't see why a mobile GPU wouldn't be able to handle quad buffers by the way - those render to system RAM. If you're trying to do quad 720p buffers with 24 bit colour, you'll run out of RAM pretty quickly even on a 4GB system, but afaik that's the only thing stopping you.
 
@mjohansson Why not double the buffers' width or height and put the left and the right view in? It's what your suggesting to be doable plus not throwing away half the data. AFAIK it's also pretty common. I don't see the need to have separate buffers for the two views. Well, if/when in 3d-rendering both sides are processed separately, one side wouldn't be slowed down by the other, but that doesn't make it essential.
 
The buffer is what you send to the display, it needs to be in the right size and sent in the right hz, the hz thing is done automatically and you dont really have any control over it as far as I know. When you select to use quad buffering I assume the GPU tells the TV here comes a 3D signal and the TV automatically switches to the right mode, if you cant tell TV to accept whatever spec that full res auto 3D is then your limited to what other modes you can use that are compatible like 1080p(60hz). If the headset support other video signals then TVs mayby theres a mode to transform 720p at 120hz to a 3D image, hmm but I think not, I dont know how the sync works because if the framerate would vary mayby all of a sudden the left and right views would be switched and the image would nolonger be 3D but just fucked up. And the hz is set by OS I just remember now, I guess thats why you need the quad buffer mode, so that the GPU knows how to sync each view with the hz nomatter of framerate your drawing.
[doublepost=1465114682,1465114157][/doublepost]Theoretically, you could in the drivers tell the GPU to use one half of the buffer to send one view to the display, but then you could just incorporate the quad buffer mode anyway :) You might also be able to keep track of sync yourself in your program, but the thing is, the way to measure time in your program is usually actually not very accurate, it might not be accurate enough for such fine tune control, I think there should be a lib for Windows with better time accuracy then SDL lib is getting for ex but Im not sure. Now were getting into oldschool stuff with manually syncing the image, thats a bit to hardcore for me.
 
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