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
