3 ms·
> the headset itself had some onboard processor that would skew and shift the frame according to the last data from the accelerometer literally right before put
by Ajedi32 4y ago
> the headset itself had some onboard processor that would skew and shift the frame according to the last data from the accelerometer literally right before putting the frame on screen
FWIW that's only needed when you don't have enough bandwidth to send an uncompressed video stream to the headset and need a decompression step that introduces additional latency (e.g. you're sending the video stream over 6 GHz Wi-Fi or USB instead of DisplayPort).
Tethered headsets do use a similar technique in situations where the game can't keep up with rendering at 90fps but that's done on the computer's GPU, not on the headset.
- fwlr 4y agoYeah, on re-reading I don’t know where I got the idea the headset was doing on-board processing. I recalled that rendering was done using positional data and they had to add a compositor post processing step afterwards using newer position data, but I hallucinated that the need for low latency was so extreme that it had to be done on the headset.
- Ajedi32 4y agoAgain, it does happen on the headset, but that's only necessary in situations where there's not enough bandwidth to send an uncompressed video stream. See Oculus Link over USB, for example: https://developer.oculus.com/blog/how-does-oculus-link-work-the-architecture-pipeline-and-aadt-explained/ https://developer.oculus.com/blog/how-does-oculus-link-work-... The diagram there shows Timewarp running on both the PC and the headset side. In headsets like the Rift or Valve Index that send video streams over HDMI or DisplayPort that extra step isn't necessary; everything happens on the PC's GPU.
- fwlr 4y agoAh, ok, that’s how I ended up with the original mistaken belief. I remembered “Timewarp is necessary” and “Timewarp can happen on the headset” and conflated them into “Timewarp necessarily has to happen on the headset”.