From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267486AbUH1SIs (ORCPT ); Sat, 28 Aug 2004 14:08:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267494AbUH1SIs (ORCPT ); Sat, 28 Aug 2004 14:08:48 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:29352 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S267486AbUH1SIp (ORCPT ); Sat, 28 Aug 2004 14:08:45 -0400 Subject: Re: reverse engineering pwcx From: Lee Revell To: Joel Jaeggli Cc: Albert Cahalan , linux-kernel mailing list , clemtaylor@comcast.net, qg@biodome.org, rogers@isi.edu In-Reply-To: <1093716249.8611.45.camel@krustophenia.net> References: <1093709838.434.6797.camel@cube> <1093710358.8611.22.camel@krustophenia.net> <1093716249.8611.45.camel@krustophenia.net> Content-Type: text/plain Message-Id: <1093716530.8611.47.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Sat, 28 Aug 2004 14:08:51 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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