Messages in this thread | | | Date | Mon, 21 Feb 2005 18:40:24 +0000 | From | Paulo Marques <> | Subject | Re: OT: Why is usb data many times the cpu hog that firewire is? |
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Gene Heskett wrote: > On Monday 21 February 2005 12:58, Oliver Neukum wrote: >[...] >>A video stream over usb1.1 must be compressed due to bandwidth >>available. Decompression needs cpu. >> > > Thats what I was afraid of, which makes using it for a motion detected > burgular alarm source considerably less than practical since the > machine must be able to do other things too. Darn. And its usb1.1 > even when plugged into a 2.0 capable port.
Depending on the camera model you can try some bandwidth reduction measures to try to make it send uncompressed video: - reduce frame rate. Something as low as 2 fps should be enough for motion detection. - reduce requested resolution. This of course depends on whether you have enough resolution or not. - selecting gray scale images. I don't know if your motion detection software is greatly affected by this, or not.
USB1.1 bandwidth is enought for 640x480, 8 bits gray scale (or color, 8 bits bayer pattern), at 3 fps.
Of course, you can always buy a USB2.0 camera :)
-- Paulo Marques - www.grupopie.com
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