On Sat, 27 Jan 2001, Gerd Knorr wrote: > In lists.linux.v4l, you wrote: > > > > For a bt848, when are the risc program(s) generated? When REQBUFS is called, > > or when VIDIOC_QBUF is called? > > QBUF. Isn't that inefficient? Last time I checked, risc program generation takes a significant length of time. > > > Packed pixel formats can use the v4l2_pix_format.bytesperline to > > > specify any padding they want. Planar formats can't have padding > > > (any objections on this? If so: why? I can't think of any useful > > > application for this...). > > > > What if you want to overlay the video into a larger image, except you're > > using planar mode? > > Any reason to do that with a planar video format? > > The main reason I see to have some padding is that you provide video data > for some other piece of hardware (vga for ewample) where you might have > some constrains on what the hardware allows you / you want to put that That was my thought. Someone might have hardware that wants a planar overlay. > > What about clipping? > > ??? We are talking about capture here, not screen overlay... Why would you never want clipping in capture? You might want to capture just a sub-region of the picture. For instance checking if the lights are out on a camera, you might just capture a few small portions of the image to see if they are black.
