Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932424AbVIKCRM (ORCPT ); Sat, 10 Sep 2005 22:17:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932427AbVIKCRM (ORCPT ); Sat, 10 Sep 2005 22:17:12 -0400 Received: from smtp4.brturbo.com.br ([200.199.201.180]:35673 "EHLO smtp4.brturbo.com.br") by vger.kernel.org with ESMTP id S932424AbVIKCRK (ORCPT ); Sat, 10 Sep 2005 22:17:10 -0400 Subject: Re: V4L: Experimental Sliced VBI API support From: Mauro Carvalho Chehab To: Andrew Morton Cc: linux-kernel@vger.kernel.org, video4linux-list@redhat.com In-Reply-To: <20050910184419.53267837.akpm@osdl.org> References: <1126401293.6807.33.camel@localhost> <20050910184419.53267837.akpm@osdl.org> Content-Type: text/plain; charset=ISO-8859-1 Date: Sat, 10 Sep 2005 23:17:11 -0300 Message-Id: <1126405031.6807.53.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3-8mdk Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1486 Lines: 34 Em S?b, 2005-09-10 ?s 18:44 -0700, Andrew Morton escreveu: > Mauro Carvalho Chehab wrote: > > > > - adds all defines, ioctls and structs needed for the sliced VBI API > > > > What is "sliced VBI"? Sorry for this... it is too much video jargon :-) VBI = Vertical Blank Interval. It is related with the way TV signals does work. It sends a line, then, it has a retrace time to allow the tube to move electrons to the beginning of the next line. This was the main reason at the beginning of analog B&W TV. There are a lot of bandwidth lost on VBI. So, lots of TV systems uses it to send other informations, like Closed Capture and Teletext. Also, broadcasters uses this as a channel to exchange information from the content producer to their subsidiaries at each city. There's already a raw VBI interface on V4L2 api, used for Closed Captions and Teletext. The decoding is doing at userlevel space and it is mostly for analog TV signals, non encoded. Encoded signals (MPEG, for example), may need also to transmit other informations (like, for example, display aspect, i.e. 4x3, widescreen...). Sliced VBI interface is a method to allow the video stream to transmit this kind of information. > Cheers, Mauro. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/