1 (edited by GoingForGold 2018-Mar-26 09:57:02)

Topic: 2 Cameras and HDD on USB-3 Hub

Dear all,

I recently found Kinovea and it looks like this is exactly what I was looking for! Very cool!

I am currently looking into investing in two cameras and was thinking of something like the Logitech C922. I also would like to record what I see in the capture screen (both cameras), but would need to have an external HDD (or possibly SSD for that matter). As my laptops don't have that many USB ports, I will need to use a hub for this.

Now my question: How realistic is it to use 2 1080p cameras and an external storage device on the same USB 3 hub? Is that going to work data-throughput wise? Or would I be better off with 2 IP Cameras?

Thanks for any advice!

Re: 2 Cameras and HDD on USB-3 Hub

It might work but I'm not 100% sure.
One thing is quite certain I think is that you will need to use an externally powered USB hub, one that will provide the standard 500mA *per port*, rather than a non powered one that will pull 500mA from the PC and share it among its downstream ports. These cameras are relatively power hungry.

If you select the MJPEG stream type in the settings the camera will compress the stream on its side and the bandwidth may be manageable. In this case Kinovea won't recompress it before storing so it's the most streamlined scenario. If the limiting factor is the I/O bandwidth at the drive, another trick would be to set the output files to automatically record one camera to the SSD and the other to the internal HDD.

Two C920 recording to an internal SSD via USB 2.0 works in Kinovea but it's already a scenario that requires the right USB setup.

If you have enough RAM on the laptop another trick could be to setup a RAM drive. It's like having a drive backed up by memory, so lower latency and greater bandwidth. I've never tried that myself but in theory it should give the maximum performances. It will compete with the size of the delay buffer if you want to use the live delay feature though, and you have to remember to copy the files over to your main drive before shutting off otherwise they are lost.

Re: 2 Cameras and HDD on USB-3 Hub

Thanks for those hints!

Could I mitigate all of this with IP cameras? Or would they add other challenges? I feel like the „same“ camera in IP is much more expensive than a USB one.