From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout1.w1.samsung.com ([210.118.77.11]:24321 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754406Ab1KXPxO (ORCPT ); Thu, 24 Nov 2011 10:53:14 -0500 Received: from euspt1 (mailout1.w1.samsung.com [210.118.77.11]) by mailout1.w1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTP id <0LV600MMP9GO8H@mailout1.w1.samsung.com> for linux-media@vger.kernel.org; Thu, 24 Nov 2011 15:53:12 +0000 (GMT) Received: from linux.samsung.com ([106.116.38.10]) by spt1.w1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTPA id <0LV6004529GOR0@spt1.w1.samsung.com> for linux-media@vger.kernel.org; Thu, 24 Nov 2011 15:53:12 +0000 (GMT) Date: Thu, 24 Nov 2011 16:53:12 +0100 From: Sylwester Nawrocki Subject: Re: [PATCH/RFC 1/2] v4l: Add a global color alpha control In-reply-to: <201111241500.23204.laurent.pinchart@ideasonboard.com> To: Laurent Pinchart Cc: Hans Verkuil , linux-media@vger.kernel.org, mchehab@redhat.com, m.szyprowski@samsung.com, jonghun.han@samsung.com, riverful.kim@samsung.com, sw0312.kim@samsung.com, Kyungmin Park Message-id: <4ECE6868.8000503@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-15 Content-transfer-encoding: 7BIT References: <1322131997-26195-1-git-send-email-s.nawrocki@samsung.com> <201111241306.11651.laurent.pinchart@ideasonboard.com> <201111241322.10889.hverkuil@xs4all.nl> <201111241500.23204.laurent.pinchart@ideasonboard.com> Sender: linux-media-owner@vger.kernel.org List-ID: On 11/24/2011 03:00 PM, Laurent Pinchart wrote: > On Thursday 24 November 2011 13:22:10 Hans Verkuil wrote: >> On Thursday, November 24, 2011 13:06:09 Laurent Pinchart wrote: >>> On Thursday 24 November 2011 12:49:00 Hans Verkuil wrote: >>>> On Thursday, November 24, 2011 12:39:54 Sylwester Nawrocki wrote: >>>>> On 11/24/2011 12:09 PM, Laurent Pinchart wrote: >>>>>> On Thursday 24 November 2011 12:00:45 Hans Verkuil wrote: >>>>>>> On Thursday, November 24, 2011 11:53:16 Sylwester Nawrocki wrote: >> Well, if that's the case, then we already have an API for that >> (http://hverkuil.home.xs4all.nl/spec/media.html#v4l2-window, field >> global_alpha). >> >> It was my understanding that this is used with a mem2mem device where you >> just want to fill in the alpha channel to the desired value. It's not used >> inside the device at all (that happens later in the pipeline). > > OK, now I understand. Maybe the documentation should describe this a bit more > explicitly ? I've modified the control description so now it is: V4L2_CID_ALPHA_COMPONENT integer Sets the alpha color component on the capture device or on the capture buffer queue of a mem-to-mem device. It is applicable to any pixel formats that contain the alpha component, e.g. _packed RGB image_ formats. And the part below Table 2.6 Bit 7 is the most significant bit. The value of a = alpha bits is undefined when reading from the driver, ignored when writing to the driver, except when alpha blending has been negotiated for a Video Overlay or Video Output Overlay or when alpha component has been configured for a Video Capture by means of V4L2_CID_ALPHA_COMPONENT control. -- Regards, Sylwester