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A comment on USB3: Why it's a bit harder than USB2. Parent comment

Re:USB3: Why it's a bit harder than USB2 by ladberg on Wednesday October 07, 2020 @03:27AM (#24706041)
I've had nearly the same experience! I was working on a project for a robotics class and my team could not figure out why our object tracking went from 30fps to ~5fps seemingly randomly. It turns out the USB3 cable wasn't fully plugged in and couldn't make full contact so it was running on USB2 and didn't have the bandwidth to send the video at 30fps.

It took a while to debug because I was absolutely convinced the slowdown was a software or GPU issue. After all, wouldn't you expect most digital ports to be binary: either be plugged in or not? It turns out with USB3 there's a third state.

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Re:USB3: Why it's a bit harder than USB2 by usr1106 on Wednesday October 07, 2020 @08:41PM (#24714475)
> After all, wouldn't you expect most digital ports to be binary: either be plugged in or not?

No. USB-A plugs for 2.x have 4 contacts that extend close to the outer edge. USB-A plugs for 3.x have additional 5 contacts close to the inner edge. If you don't insert the plug fully, you physically just get a USB 2.x connection. Nothing magic there.

https://www.techspot.com/guides/235-everything-about-usb-30/

There are more subtle problems with 3.0.

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Re:USB3: Why it's a bit harder than USB2 by Isthatablackgsd on Wednesday October 07, 2020 @12:04PM (#24709564)
> it was running on USB2 and didn't have the bandwidth to send the video at 30fps.

Mmm, I am surprised about that because USB 2.0 is fully capable of 1080p60 without issues. I have Logitech C910 and it does 1080p60 flawlessly. I wonder if it is not actually 2.0 but USB 1.1 which made sense since the transfer rate is abysmally low (1.1 does up to 12 Mbps, 2.0 is up to 480 Mbps).

But again, computers does have their quirks and can do weird & strange things that seem impossible but it is possible.

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Re:USB3: Why it's a bit harder than USB2 by usr1106 on Wednesday October 07, 2020 @12:41PM (#24710009)
> Mmm, I am surprised about that because USB 2.0 is fully capable of 1080p60 without issues. I have Logitech C910 and it does 1080p60 flawlessly. I wonder if it is not actually 2.0 but USB 1.1 which made sense since the transfer rate is abysmally low (1.1 does up to 12 Mbps, 2.0 is up to 480 Mbps).

I am not who you were responding to, but I can confirm that at 480 Mbps our Intel Realsense does not work, 5000 Mbps are mandatory. We use an Infrared stereo mode at 30 fps. I am not a my desk now and don't remember the exact details by heart.

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Re:USB3: Why it's a bit harder than USB2 by rasz on Thursday October 08, 2020 @11:19AM (#24719892)
>USB 2.0 is fully capable of 1080p60 without issues. I have Logitech C910 and it does 1080p60 flawlessly

mjpeg compressed

https://telestreamforum.forumbee.com/t/6363z0/psa-windows-10...

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Re:USB3: Why it's a bit harder than USB2 by rangibaby on Wednesday October 07, 2020 @08:59AM (#24707692)
> After all, wouldn't you expect most digital ports to be binary: either be plugged in or not?

It's always a good idea to have a known-good extra cable or two and laptop that you know has good ports. All the time and frustration you will save is definitely worth the hassle.

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Re:USB3: Why it's a bit harder than USB2 by raxxorrax on Wednesday October 07, 2020 @04:12AM (#24706248)
Full HD raw image data nets you about 5.something FPS on ~480 mbit/s USB2, which already hits physical limits. Higher standards basically just increase the number of data lanes, but we still call that serial.
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