On Thursday 14 February 2002 03:54 pm, Alan Cox wrote: > > If it is a ring buffer, what is the function of the video_mmap.frame ? > > Does it indicate which of the available frames the first one should be > > spooled to? > > Ok better idea for explaining this - grab a copy of mp1e from sourceforge > (zapping project), read io.c - thats got a nice clean example > I *think* I got the right project. Is this the stuff you are referring to: http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/zapping/zapping/src/ I'm not sure if it is or not, the io.c for that project was deleted almost 2 years ago and the last version entered before deletion hand no v4l code in it. tveng1.c has their video4linux 1 access code in it though. Anyway, if I read that code right the answer is that VIDIOCMCAPTURE ioctl must be called once for every frame you capture. If the frame in question is not yet available because it is spooling, the ioctl will block until the image is available. Did I read this right? I think that answers my biggest question.
