Question Would a USB 30 foot extender add latency for VR?

GamerCyclops

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I decided to post this in components after getting no replies in VR & AR because I realized my question is more about USB than it is VR.

With my current setup, in order to use room-scale VR with my HTC Vive I need to move my entire PC and monitor into my living room from my office. This is obviously a pretty far cry from plug and play setup, so I want to run both a USB cable and an HDMI cable from my office to the Vive link box in my living room. The rooms aren't too far from one another, and I'd route the cables along the already present Ethernet cable (which was also 30 feet, so I know these will work).

The 30 foot HDMI cable is no problem, but would I encounter issues with a USB cable of this length? I know that they're usually limited to 5 meters, but I've found active cables that advertise much further with low latency. Would it work with low enough latency to run VR?
 

AllanGH

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With the extreme variability in cable performance, you would have to test out any specific cable to know for sure.

I can say that, with video camera use, performance drops-off significantly at anything over 3 to 5 meters on my video gear, and it really doesn't matter what cable I use.
 

GamerCyclops

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With the extreme variability in cable performance, you would have to test out any specific cable to know for sure.

I can say that, with video camera use, performance drops-off significantly at anything over 3 to 5 meters on my video gear, and it really doesn't matter what cable I use.
Is that example with the video camera using an active cable? And what drops off in performance, is it a latency issue or dropped connection? That info might help
 

AllanGH

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At 10 meter lengths, I had no signal from the camera. I assumed that it just wouldn't handshake with the computer. At 7 meters length, frame rate was VERY slow and choppy....very irritating. I could back-off to about 5 meters on a Belkin cable, and things were tolerable....since it was for a USB camera on an industrial microscope, the frame rate that I got out of that was fine. For full-motion video, it wouldn't have done very well. At 3 meters, all was fine.

Everything was done on passive cabling. The only area that I did active cabling was for remote control of my stereo (decidedly low data rate) with a 15 meter active cable. I never did bother trying an active USB cable with video bandwidth signals.
 

GamerCyclops

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At 10 meter lengths, I had no signal from the camera. I assumed that it just wouldn't handshake with the computer. At 7 meters length, frame rate was VERY slow and choppy....very irritating. I could back-off to about 5 meters on a Belkin cable, and things were tolerable....since it was for a USB camera on an industrial microscope, the frame rate that I got out of that was fine. For full-motion video, it wouldn't have done very well. At 3 meters, all was fine.

Everything was done on passive cabling. The only area that I did active cabling was for remote control of my stereo (decidedly low data rate) with a 15 meter active cable. I never did bother trying an active USB cable with video bandwidth signals.
Alright, so I guess I would have to try an active cable at a higher rate myself. The only reason I hesitate is because of the high cost of a 30 foot active USB cable, but I suppose I could always return it if it doesn't work out. Thanks for the info!
 

USAFRet

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The USB spec is 5 meters for USB 2.0 and 3 meters for 3.0. Anything beyond that is ...who knows.

The reason is that USB is also a 2 way conversation. A response has to come back from the device within x nanoseconds. Longer cable = longer transmission time.

30 feet = almost 10 meters = you need an active adapter.
 

AllanGH

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The only advantage you gain with an active cable is in terms of signal quality (level and slew) at each end of the link. There is nothing that such a cable can do about propagation delays; which, since VR is your objective, will likely introduce enough lag as to be noticeable. It really is going to be up to you as tho whether that lag is intolerable, or not.
 

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