From: Lee Revell <rlrevell@joe-job.com>
To: Craig Milo Rogers <rogers@isi.edu>
Cc: QuantumG <qg@biodome.org>, linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: reverse engineering pwcx
Date: Fri, 27 Aug 2004 23:49:00 -0400 [thread overview]
Message-ID: <1093664940.8611.8.camel@krustophenia.net> (raw)
In-Reply-To: <20040828033552.GN24018@isi.edu>
On Fri, 2004-08-27 at 23:35, Craig Milo Rogers wrote:
> On 04.08.28, QuantumG wrote:
> > Craig Milo Rogers wrote:
> >
> > > Hmmm... a poster on Slashdot claims that entropy measurements
> > >imply that the pwcx code is interpolating rather that truly
> > >decompressing. Again, that's integer math and table lookups.
> > >
> > >
> >
> > http://www.amazon.com/exec/obidos/tg/detail/-/B00005R098/102-7619892-0201738?v=glance
> >
> > claims that the Logitech Quickcam Pro 3000 is a "True 640 x 480
> > resolution video capture" which is now clearly false.
>
> If the "now clearly false" is meant to be a consequence of the
> entropy measurements poster I referred to, I wouldn't jump the gun.
> On reflection, it's entirely natural for a decompressed stream to
> examine less entropy than the corresponding compressed stream!
>
Please see this slashdot thread:
http://linux.slashdot.org/comments.pl?sid=119578&threshold=3&mode=flat&commentsort=0&op=Change
The LavaRnd guys examined the pixels on the actual CCD chip. It's
160x120. The 'decompression' is just interpolation.
Lee
next prev parent reply other threads:[~2004-08-28 3:48 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-28 0:52 reverse engineering pwcx QuantumG
[not found] ` <20040828012055.GL24018@isi.edu>
[not found] ` <20040828014931.GM24018@isi.edu>
2004-08-28 3:14 ` QuantumG
2004-08-28 3:35 ` Craig Milo Rogers
2004-08-28 3:49 ` Lee Revell [this message]
2004-08-28 12:23 ` Vojtech Pavlik
2004-08-28 19:20 ` Chris Meadors
2004-08-28 3:57 ` QuantumG
2004-08-28 12:07 ` Vojtech Pavlik
2004-08-28 6:47 ` Clem Taylor
2004-08-28 12:23 ` Wouter Van Hemel
-- strict thread matches above, loose matches on Subject: below --
2004-08-28 16:17 Albert Cahalan
2004-08-28 16:25 ` Lee Revell
2004-08-28 16:56 ` Albert Cahalan
2004-08-28 17:11 ` Lee Revell
2004-08-28 18:05 ` Vojtech Pavlik
2004-08-28 17:53 ` Joel Jaeggli
2004-08-28 18:04 ` Lee Revell
2004-08-28 18:08 ` Lee Revell
2004-08-29 21:04 ` Helge Hafting
2004-08-30 7:42 ` Paul Jakma
2004-08-30 12:52 ` Albert Cahalan
2004-08-30 20:23 ` dulle
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