Re: reverse engineering pwcx

Joel Jaeggli
2004-08-28T17:54:30Z

On Sat, 28 Aug 2004, Lee Revell wrote:

> Right, as someone else pointed out, this is wrong.
>
> How do you account for the Slashdot poster's assertion that it's
> physically impossible to cram 640 x 480 worth of data down a USB 1.1
> pipe?

640x480 = 307200 pixels
x 24 bits = 7372800 bits per frame (.9MB)
x 30 fps = 221184000

so that's 221mb/s for uncompressed 640x480. dv with 16bit pcm is 25Mb/s
typically which is still a bit more than double what you can reasonably
push through a usb1.1 port. raw you can push about 1.6 fp/s at 640x480
through usb so your compression ratio needs to be order of 15 to 1 make
it fit reasonably with room for overhead.

> Lee
>
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Joel Jaeggli Unix Consulting joelja@darkwing.uoregon.edu
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