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Author Topic: USB bandwith  (Read 7151 times)

greg

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USB bandwith
« on: 18 March 2013, 12:38:13 am »

Hello Community

I'm trying to set up my Sheeva plug as a surveillance device. I tested "motion" with a webcam and it works fine. I added a USB2 hub and another webcam and only one works.
I read somewhere that USB2 can only give the bandwith for *one* webcam. Does anyone have an idea on how I can work around that?

TIA

greg
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PacoLM

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Re: USB bandwith
« Reply #1 on: 18 March 2013, 08:01:28 am »

Hi,

 Read this in order to setup the fantastic Zoneminder software for surveillance: http://www.plugcomputer.org/Documentation/howtos/zoneminder/

Regards,

PacoLM
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greg

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Re: USB bandwith
« Reply #2 on: 18 March 2013, 10:36:24 am »

Thanks for the link, but my problems is about USB, not about the surveillance software :)

greg
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Confusticated

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Re: USB bandwith
« Reply #3 on: 18 March 2013, 11:40:42 am »

Quote
only one works
I have run two cameras at 640x480 without issue.
You haven't given me very much to go on, so with the lack of any other evidence I am making the assumption it is 'operator error'.

Have you carefully read the 'motion' documentation to set up the configuration ?
You will need three configuration files if you add another camera.

1) motion.conf - master configuration
2) thread1.conf - 1st camera
3) thread2.conf - 2nd camera

NB: zoneminder is way over the top for a security camera, it is designed for managing multiple cameras for an operator console, motion is a good choice for a low power headless embedded device.
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Advocatus Diaboli - My agenda is not to give you the answer, but to guide your thoughts so you derive it for yourself!

greg

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Re: USB bandwith
« Reply #4 on: 18 March 2013, 01:24:36 pm »

Thanks for the reply, sorry I didn't give enough details.

I think I set up motion properly: I have the three files as you stated, and both cams are *detected*. However, I have that in the log:

Code: [Select]
[2] Error starting stream VIDIOC_STREAMON: No space left on device
[2] ioctl (VIDIOCGCAP): Inappropriate ioctl for device

Despite the misleading title (there is space left on device!), it seems from what I found with Google that it means "not enough bandwidth". I can reproduce the exact same thing on my desktop computer: when both cams are plugged on the same USB controller, the error occurs; however if they are plugged on different controllers, it works fine.

As there is only one controller on the Sheeva, I cannot do the same.

When you had your two cameras running at the same time, was it on a Sheeva too?

TIA

greg

PS: cams are set up at 352x288 palette 0 (YUV)
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Confusticated

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Re: USB bandwith
« Reply #5 on: 22 March 2013, 10:46:52 pm »

Quote
Error starting stream
I didn't set them up for streaming, I configured them for motion detection (as surveillance cameras, approx 4 frames per sec).
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Advocatus Diaboli - My agenda is not to give you the answer, but to guide your thoughts so you derive it for yourself!

greg

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Re: USB bandwith
« Reply #6 on: 23 March 2013, 02:37:24 pm »

Is there a way to specify such a mode in motion? I can't see how it would change the bandwith, short of closing/opening the device everytime which is very slow.

I had some success by using two different webcam, one being able to send images as jpeg, therefore reducing the bandwith. I guess it's because it's an old webcam from the USB 1 days, new webcam don't bother doing that:

New cam:
Code: [Select]
        Pixel Format: 'YUYV'
        Name        : YUV 4:2:2 (YUYV)
                Size: Discrete 640x480
                        Interval: Discrete 0.033 s (30.000 fps)
                        Interval: Discrete 0.067 s (15.000 fps)
                Size: Discrete 352x288
                        Interval: Discrete 0.033 s (30.000 fps)
                        Interval: Discrete 0.067 s (15.000 fps)
                Size: Discrete 320x240
                        Interval: Discrete 0.033 s (30.000 fps)
                        Interval: Discrete 0.067 s (15.000 fps)
                Size: Discrete 176x144
                        Interval: Discrete 0.033 s (30.000 fps)
                        Interval: Discrete 0.067 s (15.000 fps)
                Size: Discrete 160x120
                        Interval: Discrete 0.033 s (30.000 fps)
                        Interval: Discrete 0.067 s (15.000 fps)

Old webcam:

Code: [Select]
        Pixel Format: 'JPEG' (compressed)
        Name        : JPEG
                Size: Discrete 160x120
                Size: Discrete 320x240
                Size: Discrete 640x480

So I think I'll be looking for old USB1 webcams!
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