From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1QjeEv-0006ab-Uq for garchives@archives.gentoo.org; Wed, 20 Jul 2011 21:23:34 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 09BA421C126; Wed, 20 Jul 2011 21:23:06 +0000 (UTC) Received: from mail-ew0-f53.google.com (mail-ew0-f53.google.com [209.85.215.53]) by pigeon.gentoo.org (Postfix) with ESMTP id 0A43521C09C for ; Wed, 20 Jul 2011 21:22:02 +0000 (UTC) Received: by ewy8 with SMTP id 8so1005470ewy.40 for ; Wed, 20 Jul 2011 14:22:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; bh=Si9QteUAvsMo7F/oszsBujKZ7A2MNQ2a6RH6i/LZTSg=; b=uMVSKHN9lCysZRBillKvIpGjc3wdHxXlfk9LY6iUmdukGPc1DCMAdz9Vy7EwOwxUHh WnTkq0MJgigE83Wmp3hDqZ2jAzM/yMmSUIYt6Tuzf2nS5JT4WXJM6ogWnscH3Vmaa21I F9nwGbwuAkPX6hKu4tx7O+ZV786OGaD6iLQBc= Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Received: by 10.14.44.205 with SMTP id n53mr3410573eeb.113.1311196921821; Wed, 20 Jul 2011 14:22:01 -0700 (PDT) Received: by 10.14.50.203 with HTTP; Wed, 20 Jul 2011 14:22:01 -0700 (PDT) In-Reply-To: References: <1369988.ypqAZSTIHU@localhost> Date: Wed, 20 Jul 2011 14:22:01 -0700 Message-ID: Subject: Re: [gentoo-user] Re: Problem with xf86-video-ati & nvidia-drivers From: Grant To: gentoo-user@lists.gentoo.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Archives-Salt: X-Archives-Hash: 094f1ee62b7b34ae7b29b7eae48fbe82 >> ... >>>> >> I was thinking about this. =A0The digital HDMI signal must be conve= rted >>>> >> into an analog signal at some point if it's being represented as li= ght >>>> >> on a TV screen. =A0Electrical interference generated by the compute= r and >>>> >> traveling up the HDMI wire should have its chance to affect things >>>> >> (i.e. create weird shadows) at that point, right? >>>> > >>>> > Not with DFPs. =A0Those work digital even internally. =A0I assume of= course >>>> > that his HDMI TV *is* a DFP. >>>> >>>> But at some point the 1s and 0s must be converted to some sort of an >>>> analog signal if only right behind the diode. =A0A diode must be >>>> presented with a signal in some sort of analog form in order to >>>> illuminate, right? >>> >>> no. >>> >>> If your tv is a standard flat panel, the sub pixels only go from on to = off and >>> back. Nothing else. There is no analog signal, no transformation nothin= g. And >>> off means 'let light through' and on 'black' >> >> Every digital signal is encoded into an analog signal. =A0I think it >> would take some serious EMI to sufficiently change the characteristics >> of an analog signal so as to create an error in the overlying digital >> signal if that signal is traveling along a wire. =A0I can imagine it >> happens but I would think it's rare. =A0Even if that signal were >> altered, I would think it just about impossible that anything but an >> error could be produced. >> >> Whether an LED is on or off is determined by whether or not it is >> forward biased. =A0Biasing is established by analog voltages and/or >> currents, and those can be altered by EMI. =A0Again, I would think it's >> very rare that EMI could affect an LED's forward biasing and change >> its state from on to off or off to on. >> >> However, what color an LED emits is determined by the energy gap of >> the semiconductor which is very much an analog process. =A0How could it >> be anything else? =A0How do you tell a photon to emit a certain color by >> feeding it 1's and 0's? =A0There has to be at least one D/A conversion >> somewhere between the digital signal and the emittance of the LED, and >> that is the most likely point for EMI to affect the final output. >> >>> If you have an led display it is pretty much the same. All the levels y= ou see >>> are achieved with fast switching. There are no analog levels. >>> >>> Stroller is probably correct with overscan/underscan. >>> >>> But that has nothing to do with digital/analog conversion. >>> >>> >>>> Digital is just a figment of our imagination after >>>> all. >>> >>> emm, no, seriously not. >> >> It is though. =A0It only exists in the conceptual world, not the >> physical world. =A0If you want to do anything with your digital signal >> besides change it, store it, or transfer it, there must be a D/A >> conversion. > > You're thinking of PCM. (And that's what I was thinking of, earlier, > too). I assume Stroller and Volker are talking about PWM, where a > perceived analog value is achieved by rapidly turning a signal from > full-on to full-off. > > (Yes, there's no such thing as pure-digital in the physical world. The > confusion here appears to be in PWM vs PCM.) > -- > :wq Everything I said above applies to both PCM and PWM. They are only conceptual layers built on top of a physical/analog base. PWM switching from full-on to full-off and back is an analog process representing digital data in order to represent an analog signal. - Grant