On Mon, 28 Feb 2011, Laurent Pinchart wrote: > > > > I don't think snapshot capture is *that* special. I don't expect most > > > > embedded SoCs to implement snapshot capture in hardware. What usually > > > > happens is that the hardware provides some support (like two independent > > > > video streams for instance, or the ability to capture a given number of > > > > frames) and the scheduling is performed in userspace. Good quality > > > > snapshot capture requires complex algorithms and involves several > > > > hardware pieces (ISP, flash controller, lens controller, ...), so it > > > > can't be implemented in the kernel. > > > > > > I agree. > > > > Right, but sensors do need it. It is not enough to just tell the sensor - > > a per-frame flash is used and let the driver figure out, that it has to > > switch to snapshot mode. The snapshot mode has other effects too, e.g., on > > some sensors it enables the external trigger pin, which some designs might > > want to use also without a flash. Maybe there are also some other side > > effects of such snapshot modes on some other sensors, that I'm not aware > > of. > > This makes me wonder if we need a snapshot mode at all. Why should we tie > flash, capture trigger (and other such options that you're not aware of yet > :-)) together under a single high-level control (in the general sense, not to > be strictly taken as a V4L2 CID) ? Wouldn't it be better to expose those > features individually instead ? User might want to use the flash in video > capture mode for a stroboscopic effect for instance. So, you'd also need a separate control for external exposure, there are also sensors, that can be configured to different shutter / exposure / readout sequence controlling... No, we don't have to support all that variety, but we have to be aware of it, while making decisions;) Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- 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
