Trent Piepho wrote:
>
> On Mon, 27 Nov 2000, Justin Schoeman wrote:
> >
> > The mmap()ed memory area is definitely NOT guaranteed to be user
> > writable, so this would not be a good idea.
>
> So it might be read-only? Is there any reason to make it read-only?
>
> > > Also V4L and V4L2 have no concept of adjusting the analog TV timing
> > > parameters. A crude workaround is to scale and crop the image to trick the
> > > driver into giving the desired timing. This won't work for non-overlay
> > > capture.
> >
> > OK v4l2 does have "digital zoom" capabilities that can let you select a
> > rectangular subpicture. I have not implemented it for bttv2, but if
> > anybody wants to, they are welcome!
>
> That's not exactly what I was talking about. The are various parameters, the
> bt848 has HSCALE/HACTIVE/HDELAY, VSCALE/VACTIVE/VDELAY, that can be used to
> fine tune the size and position of the captured portion of the video signal.
> Does V4L2 let me pan the image to the left a few pixels worth?
It allows you to specify a "subpicture" i.e. a portion of the visible
image. This can be used for cropping the borders of the image, and
things like that.
> What if you are interesting in multiple subsections of the image? For
> example, you're looking for a object to enter the picture on the left or right
> edge, and don't care about the center.
This is not possible with the current API.
-justin
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