08-29-2018 10:18 AM
Hi There, I notice a delay between tracking update and camera image update. This makes virtual objects to "oscilate" when you move the head: they dont mach the image perfectly because image plane moves after image gets updated.
Im trying to match the delays. However, I cannot change FPS camera settings! Nothing I´ve tried works.. it just restar steamvr and the same (something about 30 and 60) value is set.
08-29-2018 11:23 AM - edited 08-29-2018 11:23 AM
The 6/21/2018 hotfix of steamvr (accessible under the beta tab of steamvr options in Steam, NOTE that this is NOT steamvr settings in steamvr itself) should resolve the issue of not being able to adjust your camera slider.
There will always be a delay between camera update and render to your HMD and the actual position update of the HMD. The position update for HMDs is coming off a 1khz IMU update with very (VERY) low latency while the camera speed is at most 60hz and the process of transferring the image data from memory on the HMD to memory in your computer, as well as potentially from RAM to VRAM (not sure on the specifics of their SDK to be honest) is nowhere near instantaneous.
At 60hz on a USB 3.0 port, the delay is very nearly negligible. I can throw and catch things accurately when the camera runs at 60hz and I do little post processing. Adding in heavy post processing and that delay can be noticeable.
08-30-2018 12:43 AM
Hmm, no, I use the 21/6/18 hotfix and also can´t adjust the slider. It is always at 60 Hz. Here they said they know the problem and trying to fix it. But I don´t think the framerate will go higher than 60 Hz, because you would need a better camera (and probably more than USB 3.0) to do this.
08-30-2018 06:27 AM
Ah, I misunderstood. The common problem right now with most of the SteamVR Betas and the released version is that the slider is typically stuck between 30-45 regardless of physical setup.
IIRC 60Hz is the specification for the cameras in the Vive Pro; however, using the device on USB 2.0 it seems incapable of reaching higher than 30Hz; this would make sense as the uncompressed video feeds at 30Hz would be just a hair under the USB 2.0 max transfer rate (405Mbps of the 480Mbps spec assuming feeds are 612*460 with 3 channels at a single byte each). The USB 3.0 spec has about 5Gbps max transfer rate, so could probably handle faster than 60hz feed without issue, but yeah I'm fairly positive I recall a spec sheet on the Vive Pro specifying 60hz for the camera.
As for this version not being adjustable. That's peculiar, it's adjustable for me on Win 10 with that build; however none of the other beta branches or trunk were adjustable and all were stuck on 40-45ish Hz with the same behavior the original poster mentioned. If they're just looking to get to 60Hz and don't care to adjust it beyond that, then this branch should work fine even if it's stuck at 60Hz.
09-06-2018 12:04 PM
Are you able to quantify the latency you are seeing? I am at 60Hz on a USB 3.0 port with a small amount of post processing (but still consistently 90FPS) but am seeing frame update times (base on 'RealDistortedFPS' difference in ImageRenderer class) of 21 to 33ms with a noticeable delay when moving my head back and forth, even at a fairly slow rate. I'm just wondering if this is normal or if I may have some other bottleneck somewhere.
09-07-2018 07:12 AM - edited 09-07-2018 07:13 AM
I'm unable to give you a measure of the latency between image capture and my perception of a rendered update; however, the delay between the ID_SEETHROUGH callback and when I Submit the texture to the compositor is typically at or under 11ms. The delay between callbacks is typically around 16ms, putting the callbacks at 60Hz.
I don't know enough about your application to assist; however, if you're using the C API, grab the Unreal or Unity Demo, and compare the results to your own to at least see if this is due to implementation. It sounds from that 21ms-33ms reference like your camera may not actually be running at the full 60Hz. Also worth verifying that any modification you're doing to the textures is done on your GPU, and that you're not juggling the texture between RAM and VRAM
12-07-2018 01:00 PM
I also have this issue. Whenever I change the frame rate under the SteamVR setting, SteamVR requires a restart. After the restart, the frame rate will change back to the original one. Any suggestion?