Hi. Ben Bridgwater sent me some time ago a cool C++ API for v4l, including examples and stuff. Its very small and should fit many needs for implementing capture in a OO way. I've uploaded it to : http://planeta.terra.com.br/informatica/gleicon/video4linux/index.html Hope it helps. ----- Original Message ----- From: "Jack Cawkwell" <jack@xxxxxxxxxxxxxxxxxxxxxxxxx> To: <video4linux-list@xxxxxxxxxx> Sent: Wednesday, July 11, 2001 4:35 AM Subject: Re: Simple capture (Newbie Question) > Ken, > > I had similar problems (on RH7.1 Linux). I found that > VIDIOCSCHAN and VIDIOCGCHAN where a bit tempremental, > and needed to be called at the right time. It failed > when I did a VIDIOCGCHAN first (is this a bug?), and > it needed to have valid values to do a VIDIOCSCHAN. > > As I program in C++ (with objects) using other peoples > C code is no good, and I had to find out what was going > wrong, not just copy a working version (useful as they > are) > > Jack > > ----- Original Message ----- > From: Ken Hirsch <khirsch11414@xxxxxxxxx> > To: video4linux-list@xxxxxxxxxx > Sent: Tue, 10 Jul 2001 17:56:19 +0100 (GMT+01:00) > Subject: Simple capture (Newbie Question) > > > 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/ > > > > > > > > _______________________________________________ > > Video4linux-list mailing list > > Video4linux-list@xxxxxxxxxx > > https://listman.redhat.com/mailman/listinfo/video4linux-list > > > > > _______________________________________________________________________ > FSmail - Get your free web-based email from Freeserve: www.fsmail.net > > > > > > > _______________________________________________ > Video4linux-list mailing list > Video4linux-list@xxxxxxxxxx > https://listman.redhat.com/mailman/listinfo/video4linux-list >
