From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id mBOEBBNU009681 for ; Wed, 24 Dec 2008 09:11:11 -0500 Received: from relay-pt2.poste.it (relay-pt2.poste.it [62.241.5.253]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id mBOE8s0l023829 for ; Wed, 24 Dec 2008 09:08:54 -0500 Received: from geppetto.reilabs.com (78.15.202.84) by relay-pt2.poste.it (7.3.122) (authenticated as stefano.sabatini-lala@poste.it) id 49517C0000005B67 for video4linux-list@redhat.com; Wed, 24 Dec 2008 15:08:54 +0100 Received: from stefano by geppetto.reilabs.com with local (Exim 4.67) (envelope-from ) id 1LFUOA-0004pV-Oi for video4linux-list@redhat.com; Wed, 24 Dec 2008 15:07:06 +0100 Date: Wed, 24 Dec 2008 15:07:06 +0100 From: Stefano Sabatini To: video4linux-list Mailing List Message-ID: <20081224140706.GA475@geppetto> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: V4L1: what's the meaning of video_window.chromakey? List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: video4linux-list-bounces@redhat.com Errors-To: video4linux-list-bounces@redhat.com List-ID: Hi all, I'm reading/studying the code of a V4L1 application and I need to understand the meaning of the video_window.chromakey field. Official docs: http://www.linuxtv.org/downloads/video4linux/API/V4L1_API.html are not particularly exhaustive, so I'm falling back to request your help here. As far as I understood it, the video_window.chromakey field is used only if video_capability.type & VID_TYPE_CHROMAKEY is true, and the video_window.chromakey value (an RGB32 value, with the first byte set to an undefined value) is set with the VIDIOCSWIN ioctl. My guess is that V4L is using the simplest possible chromakeying algorithm, so that it copies each pixel from the capture buffer to the destination buffer with a value different from video_window.chromakey. Setting: video_window.chromakey = -1; // the same as 0xffffffff for example should copy all the pixels with a value different from 0xXXffffff to the destination buffer. I wonder if this is the correct interpretation, and if the chromakeying capability (if supported) can be disabled. Many thanks in advance. Regards. -- video4linux-list mailing list Unsubscribe mailto:video4linux-list-request@redhat.com?subject=unsubscribe https://www.redhat.com/mailman/listinfo/video4linux-list