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 m1SECt4s023313 for ; Thu, 28 Feb 2008 09:12:55 -0500 Received: from mail.mediaxim.be (dns.adview.be [193.74.142.132]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id m1SECKAG028852 for ; Thu, 28 Feb 2008 09:12:20 -0500 Received: from localhost (mail.mediaxim.be [127.0.0.1]) by mail.mediaxim.be (MediaXim Mail Daemon) with ESMTP id 663DF341AB for ; Thu, 28 Feb 2008 15:12:19 +0100 (CET) Received: from [10.32.13.124] (unknown [10.32.13.124]) by mail.mediaxim.be (MediaXim Mail Daemon) with ESMTP id AB0CD34020 for ; Thu, 28 Feb 2008 15:12:17 +0100 (CET) Message-ID: <47C6C141.6040303@mediaxim.be> Date: Thu, 28 Feb 2008 15:12:17 +0100 From: Michel Bardiaux MIME-Version: 1.0 Cc: video4linux-list@redhat.com References: <47C3F5CB.1010707@mediaxim.be> <20080226130200.GA215@daniel.bse> <47C44499.7050506@mediaxim.be> <200802261815.05108.hverkuil@xs4all.nl> In-Reply-To: <200802261815.05108.hverkuil@xs4all.nl> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: Grabbing 4:3 and 16:9 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: Hans Verkuil wrote: > On Tuesday 26 February 2008 17:55:53 Michel Bardiaux wrote: >> Daniel Glöckner wrote: >>> On Tue, Feb 26, 2008 at 12:19:39PM +0100, Michel Bardiaux wrote: >>>> Here in Belgium the broadcasts is sometimes 4:3, sometimes 16:9. >>>> Currently, the card goes automatically in letterbox mode when it >>>> receives 16:9, and our software captures the 4:3 frames at size >>>> 704x576. >>> The card does not go into letterbox mode. It's the broadcaster who >>> squeezes the 16:9 picture into 432 lines surrounded by 144 black >>> lines. >> Let me rephrase to check I understood correctly. In analog TV, there >> are no anamorphic broadcasts. When the WSS (accessible via /dev/vbi, >> right?) states 16:9, then a 16:9 (sic) TV switches to a mode where it >> crops 2x72 lines, then stretches the image both horizontally and >> vertically to fill the whole 16:9 screen. Am I correct? > > Yes, this is really true. Remember that the broadcast should still work > when received by an old 4:3 TV. The only way to ensure that it still > looks OK is to letterbox it. As mentioned before PALPlus allows the > broadcaster to encode additional information encoded in the black bars > to improve the image quality (never looked into that, though). > > BTW, WSS does allow anamorphic broadcasts, although it is very rare. I > saw it once, but I've always suspected that someone made a > configuration error because anamorphic broadcasts look squashed on > normal 4:3 TVs. > >> I must admit I have difficulty believing that. Could you give me the >> URLs of sites explaining all that? > > http://en.wikipedia.org/wiki/Widescreen_signaling > > http://en.wikipedia.org/wiki/PALPlus To summarize: I know now that PALPLUS is indeed widely used in Belgium for analog TV (via cable usually); that I can detect it from WSS using libzvbi. But PALPLUS seems to be being deprecated; e.g. the wikipedia pages explain it was, but no longer is, used in the Netherlands. Just like analog-TV itself. So, unless I can find (any suggestions?) a ready-made open-source software decoder for PALPLUS, it is unlikely we will attempt to extract that info. Much better to work on digital-TV! Thanks again to all who helped. > > Regards, > > Hans > >>> Some fill the chroma part of the black lines with a PALPlus helper >>> signal. Although the algorithms to decode PALPlus are well >>> documented in ETS 300 731, I have never seen a software >>> implementation. >>> >>>> 1. How do I sense from the software that the mode is currently >>>> 16:9 or 4:3? >>> Some broadcasters use WSS to signal 16:9. >>> In Germany some signal 4:3 even on 16:9 shows. >>> Read ETSI EN 300 294. >>> >>>> 2. How do I setup the bttv so that it does variable anamorphosis >>>> instead of letterboxing? If that is at all possible of course... >>> You can't. Bttv can't stretch vertically. >>> >>> Daniel -- Michel Bardiaux R&D Director T +32 [0] 2 790 29 41 F +32 [0] 2 790 29 02 E mailto:mbardiaux@mediaxim.be Mediaxim NV/SA Vorstlaan 191 Boulevard du Souverain Brussel 1160 Bruxelles http://www.mediaxim.com/ -- video4linux-list mailing list Unsubscribe mailto:video4linux-list-request@redhat.com?subject=unsubscribe https://www.redhat.com/mailman/listinfo/video4linux-list