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Re: [Phys-l] digital video cameras



Let's take a hypothetical case. We have a 12 Mbit/sec bus called U,
a 400 Mbit/sec bus called F and a storage device capable of working
at 20 Mbit/sec called D.
A massless, frictionless experimenter connects bus U and device D in series.
He times the transfer of a 50 Mbyte file
the 400 Mbits passes bus U in 33 sec. this data is stored on D in
20 seconds - total 53 seconds.
Then he repeats the experiment using bus F and device D in series.
The same file takes 1 second to pass the bus, and 20 seconds to store in D
total 21 seconds

So the speed improvement is 53/21 = X 2.5

But wait a moment: I claimed bus F was 33 times faster.
I must have been wrong. Or was I?
:-)
And then there's the peer to peer connect - the bus sharing
to multiple PCs and so on.
Brian

At 10:17 PM 3/6/2006, you wrote:
"Firewire is the way to go. Tens to hundreds
of times better bandwidth than usb."

Not quite not even 2 X.

I have an ext. HD and a PowerBook both w/ usb and FW. I found the difference sl. less than 2X transferring the same ~ 100 Meg file and that was w/ USB 1.0! Apple goofed; my PB is supposed to have 2. So when it returns from Texas I'll try the comparison again.

Here's a believable? Site on this matter.


http://www.usb-ware.com/firewire-vs-usb.htm

bc, who didn't know some webcams have memory.


Brian Whatcott wrote:

>I have the eyeball webcam that Tom mentioned. It takes usable
>stills and short movie clips, and makes possible videophone operation.
>
>But it does not compare with even a cheap digital camcorder.
>The one we bought is a mini DV which I see is out of favor with
>Cindy. I was pleased by its X20 optical zoom, and
> X hundreds digital zoom. The resolution seems to hold up well for the
>optical zoom range at least. Firewire is the way to go. Tens to hundreds
>of times better bandwidth than usb. We needed to buy
>the PC interface, which was no problem to buy or install,
>as it happened. Here is a URL with a selection by price band,
>from <$200 to >$2000.
>
> <http://www.shop.com/op/sprod-32837-1030905>
>
>Brian Whatcott
>
>At 12:31 PM 3/6/2006, you wrote:
>
>
>>I would recommend getting the Logitech webcam.
>>They work beyond expectations and they are very cheap.
>>Tom McCarthy
>>
>>The Hawley Observatory
>>St. Paul's School
>>325 Pleasant Street
>>Concord, NH 03301
>>
>>O: 603-229-4884
>>H: 603-230-9624
>>
>>http://astro.sps.edu
>>
>>________________________________
>>
>>From: phys-l-bounces@carnot.physics.buffalo.edu
>>on behalf of Cindy Schwarz
>>Sent: Mon 3/6/2006 11:06 AM
>>To: Phys-L
>>Subject: [Phys-l] digital video cameras
>>
>>i am thinking about getting new cameras to use with loggerpro for
>>video analysis - want to get away from minidv tapes - dont want to
>>use direct to dv
>>
>>has anyone used any of the cameras with memory, SD or otherwise or
>>hard drives ?
>>
>>with macs?
>>
>>Cindy Schwarz
>>Vassar College
>>
>>
>
>
>Brian Whatcott Altus OK Eureka!
>
>
>_______________________________________________
>Forum for Physics Educators
>Phys-l@carnot.physics.buffalo.edu
>https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l
>
>
>
>
_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l


Brian Whatcott Altus OK Eureka!