ZoneMinder Forums

I have a CentOS x64 system running the latest ZM with a Trendnet IP camera and MS Lifecam Cinema as a local USB camera. Both are working fine so I tried adding a second MS LC to the same server. It appears to be recognized and I can query both with zmu. But when I add the second LC, with all the same settings as the first except now on /dev/video1, they both dont work. If I remove the second monitor from ZM, then the first works again?


root@epiphany:~# zmu -d /dev/video0 -q -V1 -v
Video Device: /dev/video0
Video Capabilities
Name: Microsoft� LifeCam Cinema(TM)
Type: 1
Can capture
Video Channels: 1
Audio Channels: 0
Maximum Width: 1280
Maximum Height: 800
Minimum Width: 48
Minimum Height: 32
Window Attributes
X Offset: 0
Y Offset: 0
Width: 640
Height: 480
Picture Attributes
Palette: 8 - YUYV
Colour Depth: 16
Brightness: 30000
Hue: 0
Colour :27197
Contrast: 32768
Whiteness: 0
Channel 0 Attributes
Name: Camera 1
Channel: 0
Flags: 0
Type: 2 - Camera
Format: 0 - PAL

root@epiphany:~# zmu -d /dev/video1 -q -V1 -v
Video Device: /dev/video1
Video Capabilities
Name: Microsoft� LifeCam Cinema(TM)
Type: 1
Can capture
Video Channels: 1
Audio Channels: 0
Maximum Width: 1280
Maximum Height: 800
Minimum Width: 48
Minimum Height: 32
Window Attributes
X Offset: 0
Y Offset: 0
Width: 640
Height: 480
Picture Attributes
Palette: 8 - YUYV
Colour Depth: 16
Brightness: 30000
Hue: 0
Colour :27197
Contrast: 32768
Whiteness: 0
Channel 0 Attributes
Name: Camera 1
Channel: 0
Flags: 0
Type: 2 - Camera
Format: 0 - PAL

it's a USB problem - ALL the available bandwidth gets reserved for the first cam, and if you plug in another one then sometimes noone gets the bandwidth (for reasons unknown to me)

most motherboards have only one USB circuit - and all 6,8 or 10 usb ports run thru an internal hub from that one (look at windows usb/ohci config in the device manager)

the only way i found around this is to install a seperate USB card (pci is fast enough) and have the second cam run thru this one, that way you have a seperate chip with the full bandwidth for each cam

interestingly XP allows you to use two cams - eg you open two instances of VLC, one for each cam - that makes me think there's some flaw in the linux kernel RE resource reservation/allocation