From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:56164 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752316Ab0GJKe3 (ORCPT ); Sat, 10 Jul 2010 06:34:29 -0400 Received: by wwb24 with SMTP id 24so5712249wwb.1 for ; Sat, 10 Jul 2010 03:34:28 -0700 (PDT) Message-ID: <4C384C9A.3090406@googlemail.com> Date: Sat, 10 Jul 2010 12:34:02 +0200 From: Frank Schaefer MIME-Version: 1.0 To: linux-media@vger.kernel.org CC: Andy Walls Subject: Re: Question about BTTV-video controls "whitecrush upper/lower" References: <4C33131B.7090101@googlemail.com> <1278682566.3385.15.camel@localhost> In-Reply-To: <1278682566.3385.15.camel@localhost> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Andy Walls schrieb: > On Tue, 2010-07-06 at 13:27 +0200, Frank Schaefer wrote: > >> Hi, >> >> there are two video controls in the Bttv-driver called "whitecrush >> upper" and "whitecrush lower". >> But what does "whitecrush" mean ? Is it the same as "white noise" ? >> The german KDE translators are currently trying to translate these >> strings... >> > > "White Crush" is Conexant's term for adapting to nonstandard or varying > Sync to White level voltage differences of the incoming video signal. > It's basically an adaptive AGC to prevent "blooming" of the video signal > due to very high Luminance levels. > > The public BT878A datasheet has terse descriptions of what the registers > settings do: they are basically upper and lower thresholds to determine > when to adapt the automatic gain control. > > The public CX25840 datasheet gives a better written description of white > crush in section 3.4.9: > > http://dl.ivtvdriver.org/datasheets/video/cx25840.pdf > > I'm actually surprised the bttv driver has those presented as user > controls at all. > > Regards, > Andy > Thank you Andy, that really helps a lot ! Regards, Frank