Hello,
we are working on a project, where we need multiple cameras connected to
embedded computer. For computer we have chosen odroid XU4 and for
cameras Logitech C920. We need at least 5 cameras running with 720p. The
problem we have is allocated USB bandwidth (cameras are using
isochronous transfer). Currently we can run 3 cameras on 720p. Image is
transferred in h264 compressed format. Writing on disk is done directly
trough memory map using V4L2 api and files on disk are really small and
using usbmon/wireshark shows ~1104kB/s (there should be a lot of USB
bandwidth left).
I tried same setups on my laptop and I don't get any better results, so
I suspect there is some space for improvement in software and it's not
odroid's fault. I tried changing different parameters in uvcvideo driver
and I think only wMaxPacketSize is affecting bandwidth allocation. And
changing that is reflected in non working camera.
Now I don't know enough about USB and linux kernel to work around this
problem and I would be very happy if you could give me some help or
directions.
If I should provide some additional information, I'll be happy to add it.
I am looking forward to hearing from you.
Best regard, Martin
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