From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:40457 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754153Ab2EGKoq (ORCPT ); Mon, 7 May 2012 06:44:46 -0400 From: Laurent Pinchart To: Sakari Ailus Cc: linux-media@vger.kernel.org Subject: Re: [media-ctl PATCH 2/3] New, more flexible syntax for media-ctl Date: Mon, 07 May 2012 12:44:45 +0200 Message-ID: <24750495.xAecYja1VB@avalon> In-Reply-To: <4FA6BF6A.4030902@iki.fi> References: <1336119883-14978-1-git-send-email-sakari.ailus@iki.fi> <2542901.vLyHxKHSqR@avalon> <4FA6BF6A.4030902@iki.fi> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: Hi Sakari, On Sunday 06 May 2012 21:14:02 Sakari Ailus wrote: > Laurent Pinchart wrote: > > On Saturday 05 May 2012 16:09:33 Sakari Ailus wrote: > ... > > >> The pixel format and the image size at the pad are clearly format > >> (VIDIOC_SUBDEV_S_FMT) but the other things are related to pads but not > >> format. > >> > >> I see them different kinds of properties of pads. That suggests we might > >> be better renaming the option (-f) to something else as well. > > > > You like breaking interfaces, don't you ? :-D > > I thought you said we have no stable release yet. :-D > > The selection interface on subdevs is currently used to change format > related things (cropping and scaling, for example) but it was one of > Sylwester's patches ("V4L: Add auto focus targets to the selections > API") that adds a focus window target to the V4L2 selection interface. I > don't see why it couldn't be present on subdevs, too. That's got nothing > to do with the image format. > > I've been pondering a bit using another option to configure things > related to selections. Conveniently "-s" is free. We could leave the > crop things to -f but remove the documentation related to them. It would then become much more complex to setup a complete pipeline in a single command line, unless we completely modify the way the command line is parsed. What would you think about renaming -f to -V (long option --video or --v4l2) ? media-ctl will hopefully be used for non-V4L2 devices in the future, so subsystem-specific options will likely be needed. > I'm fine with keeping the things as they are for now, too, but in that > case we should recognise that -f will not be for formats only. Or we > split handling selections into separate options, but I don't like that > idea either. > > >>> I find the '/' a bit confusing compared to the ' ' (but I think you find > >>> the space confusing compared to '/' :-)). I also wonder whether we > >>> shouldn't just drop 'fmt:', as there can be a single format only. > >> > >> You can set it multiple times, or you may not set it at all. That's why I > >> think we should explicitly say it's the format. > > > > Not at all makes sense, but why would you set it multiple times ? > > I guess that's not a very practical use case, albeit there may be > dependencies between the two: Guennadi had a piece of hardware where the > hardware cropping or scaling capabilities depended on the format. We don't have a way to handle that cleanly in the V4L2 API, do we ? > But not setting it at all definitely is a valid use case. -- Regards, Laurent Pinchart