问题
The openCV code below grabs simultaneous images from two cameras. It works fine in windows, with the cameras both attached to one usb 2.0 hub. When I try the same code in linux, it only has enough bandwidth for one camera at a time. I've also tried viewing the two streams at once with guvcview, same issue. What I need is some way to force the webcams to work together, possibly by setting the amount of bandwidth the driver requests.
capture = cv.CaptureFromCAM(0)
capture2 = cv.CaptureFromCAM(1)
while True:
frame = cv.QueryFrame(capture)
frame2 = cv.QueryFrame(capture2)
cv.ShowImage("w1", frame)
cv.ShowImage("w2", frame2)
if cv.WaitKey(10) != -1:
break
回答1:
I had a USB bandwidth issue with webcams (LifeCam Cinema) as well and solved it by using the FIX_BANDWIDTH quirk of the uvcvideo driver. See this answer for details on using the quirk.
Without quirk, for some USB host controllers I tried, two LifeCams worked (per controller); for others, only one. Here the controllers in one of my machine vision machines:
uli@KL04:~$ lspci | grep USB
00:1a.0 USB controller: Intel Corporation C600/X79 series chipset USB2 Enhanced Host Controller #2 (rev 06)
00:1d.0 USB controller: Intel Corporation C600/X79 series chipset USB2 Enhanced Host Controller #1 (rev 06)
03:00.0 USB controller: VIA Technologies, Inc. Device 3483 (rev 01)
0a:00.0 USB controller: ASMedia Technology Inc. Device 1142
0b:00.0 USB controller: ASMedia Technology Inc. Device 1142
(The Intel and ASMedia controllers are on the motherboard, the VIA is on a PCIe card.) Without quirk, each ASMedia controller supported only one LifeCam.
回答2:
The issue might be here that the cameras run some sort of video compression in their windows drivers, while they might run uncompressed in Linux - at a higher data rate.
If that is the case, then you may need to put them on different USB busses to make them work both at a time in Linux. This could require you to add a PCI or PCIe USB card to your system - many motherboards do only implement one USB2.0 high speed bus.
回答3:
Can you configure the webcams to use a lower resolution or frame rate and thus less bandwidth?
来源：https://stackoverflow.com/questions/6687773/two-webcams-on-one-usb-2-0-hub-works-in-windows-but-not-linux