[vlc-devel] OpenHMD branch?

Lomax lomax at clickworkorange.com
Sun May 19 18:26:26 CEST 2019

Hi Alexandre,

Thank you for spending time on this - don't worry about my long rambling 
post from Friday; if there's any useful information there then great, 
but the questions are not so important. In answer to your questions re. 
usage, I'm working on a public exhibition at a "marine knowledge centre" 
in Sweden (a registered non-profit), where the staff are involved also 
in practical science - including diving to document, sample and survey 
the marine life and seabed conditions. They have a very nice 
stereoscopic 360 underwater camera (not sure of the model but can check 
if you want) but they have no means to show its footage to the museum 
visitors - which is where I come in: amongst other things* I've been 
tasked to build a permanent exhibit with which visitors can view this 
material. I chose, perhaps foolishly, to use the Oculus Rift CV1, 
thinking it was a well established product with plenty of support. Only 
afterwards did I find out that it was nothing of the sort, and that 
indeed the whole area of stereoscopic 360 video is severely 
underdeveloped. Only proprietary (Windows/MacOS) applications seem to be 
available, which would be unsuitable for use in an exhibition; no user 
interaction should be required to launch the video, nor should the 
computer, or any OS or application GUI elements be visible, and the 
system needs to be reliable - we just want the video to play in a 
continuous loop from when the computer is switched on until it's 
switched off, and nothing else. This, and the fact that it is open 
source, is why I went with VLC - thinking the command line interface 
should make it easy to get it to start playing on boot (and it was), and 
that we could tweak anything else we might want to adjust in the source 
if needed. So our application is basically as simple as could be; 
there's no interactivity, no audio, and no motion tracking beyond 
rotation, and the material is pretty "standard" (at least as far as any 
standards are established). But I've now spent 50hrs+ on this, and 
€1500+ on hardware, yet have nothing to show, which means I'll have some 
tough explaining to do...

I've taken some quick snaps of what I see[1-4] - please let me know if 
there's any specific information I can provide which may help getting to 
the bottom(!) of this.



*) For example, I've also built a remote controlled submerged camera out 
in the water, based on an Axis PTZ PoE camera, which can be controlled 
with an analogue joystick from inside a mock "submarine". This is 2D HD 
and works beautifully on a Pi3 connected to a curved 27" monitor.

1: https://i.imgur.com/WGzfcY4.jpg
2: https://i.imgur.com/bAy39Wy.jpg
3: https://i.imgur.com/jWTbBxn.jpg
4: https://i.imgur.com/SswgW8T.jpg

> Hi, I'll answer to your bigger previous post later, but first, thank
> you for your comprehensive testing of this branch and the report you
> did.
> The code is extracting lenses properties from OpenHMD to match the
> projection with the way the headset works. If there is no HMD, there
> is no projection. The "circle-like" effect is a colour and pixel
> transformation (using panotools parameters) to match the lenses used
> by the headset, which is needed because of the low distance between
> the eyes and the screen in the headset.
> What is your setup, do you have screenshot of the issue ? This code was
> taylored for headset demos so there are probably a lot of different
> hacks and mostly only headset playback is probably correctly handled in
> this version.
> I can try to provide you a version with some fixes for the demo if you
> want and if it's not too much time consuming, but I would like to know
> the exact use case for your demo. You can ping me as "unidan" on irc if
> you need some help on the build itself.
> Greats,
> --
> Alexandre Janniaux,
> VideoLabs

More information about the vlc-devel mailing list