For the moment, I would like video kept out of motion tracked audio on headphones. I want this to be a system where I can sit in a rocking chair and listen to music of many kinds on a good pair of headphones and the headtracking is only to reinforce the audio image.
Umashankar p.s. I have ordered bits to build a usb contraption to turn headmovements into xy. Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10 From: Stefan Schreiber<mailto:st...@mail.telepac.pt> Sent: Tuesday, February 2, 2016 3:32 AM To: Surround Sound discussion group<mailto:sursound@music.vt.edu> Subject: Re: [Sursound] Never do electronic in public. David McGriffy wrote: > >I got a GearVR recently and it does work better than Google Cardboard. Much >of this is just comfort, I think, but I understand that it has its own >gyros, mostly because they are faster. 'Heresay' is that the Oculus Rift >samples at least 1000Hz. I have actually written an audio rate rotate that >could handle this, but it does seem like overkill. At normal head turning >rates, I find interpolating the rotation within each block to be enough. > > > http://blogs.valvesoftware.com/abrash/latency-the-sine-qua-non-of-ar-and-vr/ (Written by a super-expert of VR) > Assuming accurate, consistent tracking (and that’s a big if, as I’ll > explain one of these days), the enemy of virtual registration is > latency. < If too much time elapses between the time your head starts > to turn and the time the image is redrawn to account for the new pose, > the virtual image will drift far enough so that it has clearly wobbled > (in VR), or so that is obviously no longer aligned with the same > real-world features (in AR). > (Elaboration:) > Suppose you rotate your head at 60 degrees/second. That sounds fast, > but in fact it’s just a slow turn; you are capable of moving your head > at hundreds of degrees/second. Also suppose that latency is 50 ms and > resolution is 1K x 1K over a 100-degree FOV. Then as your head turns, > the virtual images being displayed are based on 50 ms-old data, which > means that their positions are off by three degrees, which is wider > than your thumb held at arm’s length. Put another way, the object > positions are wrong by 30 pixels. Either way, the error is very > noticeable. In other words: There are speed/delay problems, there are sync problems, there might be more... > You can do prediction to move the drawing position to the right place, > and that works pretty well most of the time. Unfortunately, when there > is a sudden change of direction, the error becomes even bigger than > with no prediction. > Tracking latency is highly dependent on the system used. An IMU (3-DOF > gyro and 3-DOF accelerometer) has very low latency – on the order of 1 > ms – but drifts. < In particular, position derived from the > accelerometer drifts badly, because it’s derived via double > integration from acceleration. > Camera-based tracking doesn’t drift, > but has high latency due to the need to capture the image, transfer it > to the computer, and process the image to determine the pose; that can > easily take 10-15 ms. < Right now, one of the lowest-latency > non-drifting accurate systems out there is a high-end system from NDI, > which has about 4 ms of latency, so we’ll use that for the tracking > latency. > > It would be far easier and more generally applicable to have the > display run at 120 Hz, which would immediately reduce display latency > to about 8 ms, bringing total latency down to 12-14 ms. (s. PlaystationVR...) > If you ever thought that AR/VR was just a simple matter of showing an > image on the inside of glasses or goggles, I hope that by this point > in the blog it’s become clear just how complex and subtle it is to > present convincing virtual images – and we’ve only scratched the surface. Wise words... (No, really!) But not to get stuck and despair: Motion-tracked audio seems to be sooooo much easier to realize... Best regards, Stefan _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on. -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20160202/64330e2c/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
