FloatImg/v4l2/v4l2grab.c

   /* V4L2 video picture grabber
       Copyright (C) 2009 Mauro Carvalho Chehab <mchehab@infradead.org>

       This program is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published by
       the Free Software Foundation version 2 of the License.

       This program is distributed in the hope that it will be useful,
       but WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
       GNU General Public License for more details.
     */

    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <fcntl.h>
    #include <errno.h>
    #include <sys/ioctl.h>
    #include <sys/types.h>
    #include <sys/time.h>
    #include <sys/mman.h>
    #include <linux/videodev2.h>
    #include <libv4l2.h>

    #define CLEAR(x) memset(&(x), 0, sizeof(x))

    struct buffer {
	    void   *start;
	    size_t length;
    };

int		verbosity;

/* --------------------------------------------------------------------- */

static void xioctl(int fh, int request, void *arg)
{
int r;

do {
	r = v4l2_ioctl(fh, request, arg);
	} while (r == -1 && ((errno == EINTR) || (errno == EAGAIN)));

if (r == -1) {
	fprintf(stderr, "error %d, %s\n", errno, strerror(errno));
	exit(EXIT_FAILURE);
	}
}
/* --------------------------------------------------------------------- */
void help(int v)
{
puts("options :");
puts("\t-d /dev/?\tselect video device");
puts("\t-n NNN\t\thow many frames ?");
puts("\t-p NNN\t\tperiod in seconds");
puts("\t-v\t\tincrease verbosity");
exit(0);
}
/* --------------------------------------------------------------------- */

    int main(int argc, char **argv)
    {
	    struct v4l2_format              fmt;
	    struct v4l2_buffer              buf;
	    struct v4l2_requestbuffers      req;
	    enum v4l2_buf_type              type;
	    fd_set                          fds;
	    struct timeval                  tv;
	    int                             r, fd = -1;
	    unsigned int                    i, n_buffers;
	    char                            *dev_name = "/dev/video0";
	    char                            out_name[256];
	    FILE                            *fout;
	    struct buffer                   *buffers;

	int		period = 10;		/* delai entre les captures */
	int		nbre_capt = 1;		/* nombre de captures */
	int		opt;

while ((opt = getopt(argc, argv, "d:hn:p:v")) != -1) {
	switch(opt) {
		case 'd':	dev_name = optarg;		break;
		case 'h':	help(0);			break;
		case 'n':	nbre_capt = atoi(optarg);	break;
		case 'p':	period = atoi(optarg);		break;
		case 'v':	verbosity++;			break;
		}
	}



fd = v4l2_open(dev_name, O_RDWR | O_NONBLOCK, 0);
if (fd < 0) {
	perror("Cannot open device");
	exit(EXIT_FAILURE);
	}

CLEAR(fmt);
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width       = 640;
fmt.fmt.pix.height      = 480;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;
xioctl(fd, VIDIOC_S_FMT, &fmt);
if (fmt.fmt.pix.pixelformat != V4L2_PIX_FMT_RGB24) {
	printf("Libv4l didn't accept RGB24 format. Can't proceed.\n");
	exit(EXIT_FAILURE);
	}
if ((fmt.fmt.pix.width != 640) || (fmt.fmt.pix.height != 480)) {
	printf("Warning: driver is sending image at %dx%d\n",
			    fmt.fmt.pix.width, fmt.fmt.pix.height);
	}

CLEAR(req);
req.count = 2;
req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_MMAP;
xioctl(fd, VIDIOC_REQBUFS, &req);

buffers = calloc(req.count, sizeof(*buffers));
for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
	CLEAR(buf);

	buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	buf.memory      = V4L2_MEMORY_MMAP;
	buf.index       = n_buffers;

	xioctl(fd, VIDIOC_QUERYBUF, &buf);

	buffers[n_buffers].length = buf.length;
	buffers[n_buffers].start = v4l2_mmap(NULL, buf.length,
				PROT_READ | PROT_WRITE, MAP_SHARED,
				fd, buf.m.offset);

	if (MAP_FAILED == buffers[n_buffers].start) {
		perror("mmap");
		exit(EXIT_FAILURE);
		}
	}

for (i = 0; i < n_buffers; ++i) {
	CLEAR(buf);
	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	buf.memory = V4L2_MEMORY_MMAP;
	buf.index = i;
	xioctl(fd, VIDIOC_QBUF, &buf);
	}

type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

xioctl(fd, VIDIOC_STREAMON, &type);
for (i = 0; i < nbre_capt; i++) {
	do	{
		FD_ZERO(&fds);
		FD_SET(fd, &fds);

		/* Timeout. */
		tv.tv_sec = 2;
		tv.tv_usec = 0;

		r = select(fd + 1, &fds, NULL, NULL, &tv);
		} while ((r == -1 && (errno = EINTR)));

	if (r == -1) {
		perror("select");
		return errno;
		}

	CLEAR(buf);
	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	buf.memory = V4L2_MEMORY_MMAP;
	xioctl(fd, VIDIOC_DQBUF, &buf);

	sprintf(out_name, "out%03d.ppm", i);
	if (verbosity) fprintf(stderr, "--> %s\n", out_name);

	fout = fopen(out_name, "w");
	if (!fout) {
		perror("Cannot open image");
		exit(EXIT_FAILURE);
		}
	fprintf(fout, "P6\n%d %d 255\n",
			    fmt.fmt.pix.width, fmt.fmt.pix.height);
	fwrite(buffers[buf.index].start, buf.bytesused, 1, fout);
	fclose(fout);
	if (nbre_capt > 1 && period) {
		sleep(period);
		}

	xioctl(fd, VIDIOC_QBUF, &buf);
}

type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
xioctl(fd, VIDIOC_STREAMOFF, &type);
for (i = 0; i < n_buffers; ++i) {
	v4l2_munmap(buffers[i].start, buffers[i].length);
	}

v4l2_close(fd);

return 0;
}