On Monday 22 November 2010 12:34:04 Laurent Pinchart wrote: > On Monday 22 November 2010 12:23:49 Hans de Goede wrote: > > On 11/22/2010 11:59 AM, Laurent Pinchart wrote: > > > On Sunday 21 November 2010 00:50:59 Shuzhen Wang wrote: > > >> Hello, Laurent, > > >> > > >> Thank you for the reply. > > >> > > >> In our case, most of the time the sensor outputs bigger image size > > >> than the output size, so the ISP hardware does downscaling. > > >> When zooming in, we can do cropping, and less downscaling to achieve > > >> the same output size. All these happen under of the hood of ISP > > >> driver. That's why I said it was like optical zoom to the > > >> application. > > >> > > >> So if "digital zoom == cropping and upscaling", then I don't think my > > >> case fits in digital zoom category. > > > > > > Digital zoom is cropping and scaling. Whether it's downscaling or > > > upscaling (or even no scaling it all for a specific resolution) is not > > > really relevant here. It depends on the output resolution but it's > > > still digital zoom that should be implemented using the crop API. > > > > Not sure I agree with this, given that AFAIK no application actually uses > > the crop API, and that almost no mere human seems to understand the crop > > API, Oh, and if our current crop API sucks, let's make a new one :-) > > I would like to advocate for exporting digital zoom as a separate > > control (for those cases were the hardware adds something to merely doing > > this in software). > > I disagree with that :-) > > The purpose of V4L drivers is to let userspace control the hardware. If we > added a digital zoom control drivers would then need to implement policies > (for instance how do you configure crop settings to get a linear zoom value > ?) and that doesn't belong to kernelspace. > > If the hardware can perform cropping and scaling, let's expose that to > applications as cropping and scaling. Whether they use it to implement > digital zoom, or for an entirely different purpose, is up to them. I don't > want to see drivers exposing cropping and scaling as zoom, pan and tilt > CIDs. -- 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
