On Thu, 13 Jan 2005, Michael Chaney wrote:
> On Thu, Jan 13, 2005 at 02:17:38PM +0800, Rowel Atienza wrote:
> > > Anyway, if you somehow want to support those cards that can receive
> > > from up to 16 cameras, I'm not sure if they would work under Linux.
I
> >
> > At 30 frame/sec and 320X240 grayscale resolution, you will need:
> >
> > 30*320*240*16*8 = 294912000 bits/sec
>
> Two bad assumptions:
>
> 1. 30 FPS - Security cameras typically do far fewer than that.
That's right if you are recording as the earlier post said but if
you are motion detecting you can not compress your images and apply motion
detection since jpeg/mpg are lossy compression algos. If you insisted you
will end up with a lot of false positives even with a simple motion
detection like background subtraction. Optical flow techniques will
obviously not work at all.
> 2. No compression - JPEG compression is typical, and will drop the image
> size dramatically
Many webcam chipsets are in fact built with mpeg encoder not just
jpeg.
rowel
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