RVMedia doesn't work with 2 or more same webcam

[dumbow]

Hi
I've been trying the RVMedia for a few days, I was using 5 Microsoft USB WebCam for a 3D project.
However, RVMedia doesn't work while opening 2 or more Microsoft USB WebCams. But if you open 1 Microsoft USB WebCam and 1 laptop internal webcam, they both work well.
So, How can I handle this problem?
Thank you.

[Sergey Tkachenko]

Do these cameras work at the same time in another application?

Do you use a USB hub connected to the same USB port? The programmer said that one USB port with connected USB hub does not have enough power for multiple web cameras. And you need USB host controller card.

[dumbow]

Thanks for your reply.
I tested all the demos in RVMedia package they didn't work, just like my application.
Yes I connected all cameras to a powered USB 3.0 hub as below. Maybe there is a host controller in it? and then I guess this has noting to do with the power issue.
I think your idea of the controllor make some sence, because I tried to connect 2 cameras to the laptop's internal usb ports, then 2 of the cameras worked. but the third one didn't work nevertheless.
Thanks again.

微信图片_20170317175123.jpg (42.36 KiB) Viewed 23626 times

[Sergey Tkachenko]

I mean it may be not a software, but a hardware problem, if all these cameras at the end are connected to a single USB port, it does not have enough bandwidth to work with them.
The developer said that you main need not a hub connected to existing USB port but a card adding new USB ports, like this one

[dumbow]

Thank you, Sergey.
I bought 2 of those PCI-USB cards, and 5 webcams worked well. and the single USB port for each camera still was not enough, I plug them into every port which is under a single USB controller. Actually, The CPU is another problem, now they can work well with the mode 1920*1080 16bit YUY2, and cost 55% CPU resource. IF they work with 1920*1080 24bit mpeg, then 3 of them would cost 100% CPU resource of the core i5.

[Sergey Tkachenko]

Currently, I have no ideas about optimization of RVMedia.
You can try using RenderMode = rvmrmOpenGL in viewers, but I do not think it will help a lot in this case.
Probably, in future, we will implement using OpenGL/DirectX for displaying multiple videos in a single window, it may help. But it is not in plans for near future.
So, currently the only solution is lowering video resolution and FramePerSec value.