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by nsxwolf 2338 days ago
Is this appropriate for creating a wireless HDMI interface for VR headsets?
4 comments

"That chip was the SB9210 from SiBeam. This part was originally intended to be used for WirelessHD, a protocol for wireless video streaming that never took off. ...at one time they were included in some smart TVs and in some high end laptops."

It sounds like it would be very suitable for a VR headset.

I am pretty sure HTC's Vive Wireless adapter uses a 60GHz link made by Intel ("WiGig").
Yep. It’s already being done by oculus or one of those VR startups.

https://www.displaylink.com/vr

Datasheet says it add 5ms latency, latency in VR causes nausea.
I'm not up to date on VR tech - is the video memory on board the VR headset? If the memory is onboard, you could do some simple rotations and translations on the current frame while the render pipeline caught up.
There's an overview of some of the various techniques that Oculus uses here: https://uploadvr.com/reprojection-explained/
5ms isn't yet at nausea levels though...
In 2014, Michael Abrash gave a talk summarizing what's needed for a feeling of presence in VR. He said 20 ms motion-to-photon latency is required for the virtual world to feel like it's "nailed in place". So 5 ms is 25% of the latency budget.
Not all motion-to-photon latency is created equal.

EDIT: To clarify what I meant, HMDs typically use techniques like ATW/ASW/etc (link posted by Rebelgecko) to do just-in-time correction of the rendered image. The end-to-end motion-to-photon latency of the entire pipeline grows but the part that generates "sick" is very short.

The number I've heard, don't ask me from where, is 16 ms.
That's framerate (how often images need to be rendered) at 60hz. Latency is separate from that: you can have a 60hz framerate with 24h latency if you watch a video you recorded yesterday.

In the parent's case, 20ms latency from movement to visible motion is part of the pipeline that:

- reads input

- evaluates solution

- returns solution to your screen

All kinds of things add to this latency: polling frequency of your input device, bus speed of the device, how fast you can update the world, how fast you can render the update, how quickly that updated image can be sent to the screen, how quickly the screen is able to turn this into visible light. etc.

60FPS ~= 16.67ms/frame. So if you don't want to drop frames on a 60Hz monitor, your frame time budget is 16ms. If you want input to appear on the next frame, you've got at most 16ms. If you're targeting a 120Hz monitor then you've got 8ms. Etc.
I think his point mught be "adds" (increasing existing latency by 5ms)
I haven't used it but the reports I have seen say the vive wireless seems to work fine without noticeable latency.