Re: reverse engineering pwcx

Lee Revell
2004-08-28T18:08:48Z

On Sat, 2004-08-28 at 14:04, Lee Revell wrote:
> On Sat, 2004-08-28 at 13:53, Joel Jaeggli wrote:
> > On Sat, 28 Aug 2004, Lee Revell wrote:
> > >
> > > 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.
>
> 15 to 1 is impossible without lossy compression.

Disregard, Vojtech's post clears things up.

Lee