Hi Shuzhen, On Saturday 20 November 2010 00:17:23 Shuzhen Wang wrote: > Hello, > > I am working on a SOC V4L2 driver, and need to implement zoom > functionality. > > From application, there are 2 ways to do zooming. The 1st way is to use > cropping and scaling as described in section 1.11.1. The application needs > to figure out what the steps will be, and calling VIDIOC_S_CROP. > > The 2nd way is to use V4L2_CID_ZOOM_ABSOLUTE and V4L2_CID_ZOOM_RELATIVE as > described by Laurent in > http://video4linux-list.1448896.n2.nabble.com/RFC-Zoom-controls-in-V4L2- td1451987.html. > > Our camera hardware supports digital zoom. However, it acts LIKE optical > zoom because it doesn't do upscaling, so no video quality is sacrificed. How can you apply a digital zoom, keeping the output size constant, without performing upscaling ? > As a driver writter, is it okay to support only V4L2_CID_ZOOM_ABSOLUTE and > V4L2_CID_ZOOM_RELATIVE? > > I guess it also depends on how zooming is done for most of the V4L2 user > application out there. The V4L2_CID_ZOOM_* controls are really meant for optical zoom. Digital zoom should be implemented using cropping. -- Regards, Laurent Pinchart -- 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
