From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from fg-out-1718.google.com ([72.14.220.155]:53122 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754506AbZGNQcZ (ORCPT ); Tue, 14 Jul 2009 12:32:25 -0400 Received: by fg-out-1718.google.com with SMTP id e21so921611fga.17 for ; Tue, 14 Jul 2009 09:32:24 -0700 (PDT) Message-ID: <4A5CB315.5050300@googlemail.com> Date: Tue, 14 Jul 2009 18:32:21 +0200 From: Michael Riepe MIME-Version: 1.0 To: aldoric@gmx.de CC: linux-media@vger.kernel.org Subject: Re: [Question] USB-Web-Cam becomes slower as darker the image becomes References: <20090714161428.49520@gmx.net> In-Reply-To: <20090714161428.49520@gmx.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi! aldoric@gmx.de wrote: > Hello, > > I'm new to v4l-development. I was able to get the raw image into my application successfully. But the current problem is not only in limited to my self-developed application. > > All of my USB-webcams will get less FPS as darker the image becomes. In optimal cases I get around 30 frames per second. But if it's really dark I only get around 2-3 FPS. I suppose the camera (or the driver) is increasing the exposure time to compensate for the lack of light and/or reduce noise. > I think that it might be the software gamma-correction. On v4l2ucp I didn't find a way to disable it. I don't think that will help. But you may try to turn off auto-exposure. -- Michael "Tired" Riepe X-Tired: Each morning I get up I die a little