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- <programlisting>
- /* 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 "../libv4l/include/libv4l2.h"
- #define CLEAR(x) memset(&(x), 0, sizeof(x))
- struct buffer {
- void *start;
- size_t length;
- };
- 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);
- }
- }
- int main(int argc, char **argv)
- {
- struct <link linkend="v4l2-format">v4l2_format</link> fmt;
- struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;
- struct <link linkend="v4l2-requestbuffers">v4l2_requestbuffers</link> req;
- enum <link linkend="v4l2-buf-type">v4l2_buf_type</link> 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;
- 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 < 20; 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);
- 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);
- 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;
- }
- </programlisting>
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