Hello I am probably repeating a question that has been asked a 1000 times but here it goes. I just want to capture an image from my Booktree device (WinTV card) and manipulate the stream in memory. I don't care about printing it out to screen. I am certainly a newbie programmer and reading over the api on the V4L just doesn't sink in enough. I've been using the code from below (vgrabber.c by Phil Blundell) however evrytime I get to the read function the program hangs. I read on the API page that not all devices can be read from so I might have to use the mmap funtion. However I have not found an example of this that is easy to follow for a newbie and was wondering if there was any available. Also I am having troubles switching tuners (I am trying to go to Composite 1 in) can anyone see why this code is failing? struct video_channel chan; chan.channel=1; if (ioctl(fd, VIDIOCGCHAN, &chan) < 0) { perror("VIDIOCGCHAN"); fprintf(stderr, "(" FILE " Didn't Work"); close(fd); exit(1); chan.channel=1; chan.type=VIDEO_TYPE_CAMERA; if (ioctl(fd, VIDIOCSCHAN, &chan) < 0) { perror("VIDIOGSCHAN"); fprintf(stderr, "(" FILE " Didn't work"); close(fd); exit(1); This code fails at the ioctl VIDIOCSCHAN call. Thanks for any help you might be able to offer. int main(void) { int fd = open(FILE, O_RDONLY), f; struct video_capability cap; struct video_window win; struct video_picture vpic; unsigned char *buffer, *src; int bpp = 24, r, g, b; unsigned int i, src_depth; if (fd < 0) { perror(FILE); exit(1); } if (ioctl(fd, VIDIOCGCAP, &cap) < 0) { perror("VIDIOGCAP"); fprintf(stderr, "(" FILE " not a video4linux device?)\n"); close(fd); exit(1); } if (ioctl(fd, VIDIOCGWIN, &win) < 0) { perror("VIDIOCGWIN"); close(fd); exit(1); } if (ioctl(fd, VIDIOCGPICT, &vpic) < 0) { perror("VIDIOCGPICT"); close(fd); exit(1); } if (cap.type & VID_TYPE_MONOCHROME) { vpic.depth=8; vpic.palette=VIDEO_PALETTE_GREY; /* 8bit grey */ if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) { vpic.depth=6; if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) { vpic.depth=4; if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) { fprintf(stderr, "Unable to find a supported capture format.\n"); close(fd); exit(1); } } } } else { vpic.depth=24; vpic.palette=VIDEO_PALETTE_RGB24; if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) { vpic.palette=VIDEO_PALETTE_RGB565; vpic.depth=16; if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) { vpic.palette=VIDEO_PALETTE_RGB555; vpic.depth=15; if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) { fprintf(stderr, "Unable to find a supported capture format.\n"); return -1; } } } } buffer = malloc(win.width * win.height * bpp); if (!buffer) { fprintf(stderr, "Out of memory.\n"); exit(1); } do { int newbright; read(fd, buffer, win.width * win.height * bpp); f = get_brightness_adj(buffer, win.width * win.height, &newbright); if (f) { vpic.brightness += (newbright << 8); if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) { perror("VIDIOSPICT"); break; } } } while (f); fprintf(stdout, "P6\n%d %d 255\n", win.width, win.height); src = buffer; for (i = 0; i < win.width * win.height; i++) { READ_VIDEO_PIXEL(src, vpic.palette, src_depth, r, g, b); fputc(r>>8, stdout); fputc(g>>8, stdout); fputc(b>>8, stdout); } close(fd); } __________________________________________________ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail http://personal.mail.yahoo.com/