Using Video4Linux "1" (don't know about v4l2) you can only scale the picture down; that may be a bt848 limitation. You can scale from a minimum of 32 by 32 pixels "up" to 640x480 (assuming NTSC; this is 1::1 or no scaling). Cropping is not directly supported but you can do it by blocking out the part of the picture to be cropped using clipping rectangles. For example if you want to just display the top-left 1/4 of a 640x480 picture (that is, 320x240), output a 640x480 window with 2 clip rects, blocking the top-right quarter and bottom half of the picture with clipping rectangles. I believe that part of the picture can extend off the screen (bounds of the frame buffer) as long as that video is blocked with a clipping rect. Note that the bttv/bt848 driver actually always uses clipping bitmaps, so you can even crop to irregular shapes; see my previous postings in the FAQ. Peter Kaczowka Ucentric Systems LLC Abheek Anand wrote: > Hi > > I would like to use the scaling and cropping features in the bt848 > chipset. Are there any ioctls etc in the linux driver to allow me to do > that (by setting the hscale/hactive register etc?). > Alternately, i would appreciate help in pointers to programming the bttv > register: specifically in the hactive/hscale/vactive/vscale registers. > > Thanks > Abheek > > _______________________________________________ > Video4linux-list mailing list > Video4linux-list@xxxxxxxxxx > https://listman.redhat.com/mailman/listinfo/video4linux-list
