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 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
