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- /*
- * V4L2 video capture example
- *
- * This program can be used and distributed without restrictions.
- */
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <assert.h>
- #include <getopt.h> /* getopt_long() */
- #include <fcntl.h> /* low-level i/o */
- #include <unistd.h>
- #include <errno.h>
- #include <malloc.h>
- #include <sys/stat.h>
- #include <sys/types.h>
- #include <sys/time.h>
- #include <sys/mman.h>
- #include <sys/ioctl.h>
- #include <asm/types.h> /* for videodev2.h */
- #include <linux/videodev2.h>
- #include <iostream>
- #include <fstream>
- #include <sstream>
- using namespace std;
- int i = 0;
- #define CLEAR(x) memset (&(x), 0, sizeof (x))
- struct buffer {
- void * start;
- size_t length;
- };
- static char * dev_name = NULL;
- static int fd = -1;
- struct buffer * buffers = NULL;
- static unsigned int n_buffers = 0;
- static void errno_exit(const char * s) {
- fprintf(stderr, "%s error %d, %s\n", s, errno, strerror(errno));
- exit(EXIT_FAILURE);
- }
- static int xioctl(int fd, int request, void * arg) {
- int r;
- do
- r = ioctl(fd, request, arg);
- while (-1 == r && EINTR == errno);
- return r;
- }
- static void process_image(const void * p) {
- ++i;
- fputc('.', stdout);
- fflush(stdout);
- std::stringstream out;
- out << "capt-" << i << ".raw";
- ofstream outfile(out.str().c_str(), ofstream::binary);
- outfile.write((const char*) p, buffers[0].length);
- outfile.close();
- }
- static int read_frame(void) {
- struct v4l2_buffer buf;
- CLEAR (buf);
- buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- buf.memory = V4L2_MEMORY_MMAP;
- if (-1 == xioctl(fd, VIDIOC_DQBUF, &buf)) {
- switch (errno) {
- case EAGAIN:
- return 0;
- case EIO:
- default:
- errno_exit("VIDIOC_DQBUF");
- }
- }
- assert (buf.index < n_buffers);
- process_image(buffers[buf.index].start);
- if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
- errno_exit("VIDIOC_QBUF");
- return 1;
- }
- static void mainloop(void) {
- unsigned int count;
- count = 100;
- while (count-- > 0) {
- for (;;) {
- fd_set fds;
- struct timeval tv;
- int r;
- FD_ZERO (&fds);
- FD_SET (fd, &fds);
- /* Timeout. */
- tv.tv_sec = 2;
- tv.tv_usec = 0;
- r = select(fd + 1, &fds, NULL, NULL, &tv);
- if (-1 == r) {
- if (EINTR == errno)
- continue;
- errno_exit("select");
- }
- if (0 == r) {
- fprintf(stderr, "select timeout\n");
- exit(EXIT_FAILURE);
- }
- if (read_frame())
- break;
- /* EAGAIN - continue select loop. */
- }
- }
- }
- static void start_capturing(void) {
- unsigned int i;
- enum v4l2_buf_type type;
- for (i = 0; i < n_buffers; ++i) {
- struct v4l2_buffer buf;
- CLEAR (buf);
- buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- buf.memory = V4L2_MEMORY_MMAP;
- buf.index = i;
- if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
- errno_exit("VIDIOC_QBUF");
- }
- type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- if (-1 == xioctl(fd, VIDIOC_STREAMON, &type))
- errno_exit("VIDIOC_STREAMON");
- }
- static void uninit_device(void) {
- unsigned int i;
- for (i = 0; i < n_buffers; ++i)
- if (-1 == munmap(buffers[i].start, buffers[i].length))
- errno_exit("munmap");
- free(buffers);
- }
- static void init_mmap(void) {
- struct v4l2_requestbuffers req;
- CLEAR (req);
- req.count = 4;
- req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- req.memory = V4L2_MEMORY_MMAP;
- if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req)) {
- if (EINVAL == errno) {
- fprintf(stderr, "%s does not support "
- "memory mapping\n", dev_name);
- exit(EXIT_FAILURE);
- } else {
- errno_exit("VIDIOC_REQBUFS");
- }
- }
- if (req.count < 2) {
- fprintf(stderr, "Insufficient buffer memory on %s\n", dev_name);
- exit(EXIT_FAILURE);
- }
- buffers = (buffer*) calloc(req.count, sizeof(*buffers));
- if (!buffers) {
- fprintf(stderr, "Out of memory\n");
- exit(EXIT_FAILURE);
- }
- for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
- struct v4l2_buffer buf;
- CLEAR (buf);
- buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- buf.memory = V4L2_MEMORY_MMAP;
- buf.index = n_buffers;
- if (-1 == xioctl(fd, VIDIOC_QUERYBUF, &buf))
- errno_exit("VIDIOC_QUERYBUF");
- buffers[n_buffers].length = buf.length;
- buffers[n_buffers].start = mmap(NULL /* start anywhere */, buf.length,
- PROT_READ | PROT_WRITE /* required */,
- MAP_SHARED /* recommended */, fd, buf.m.offset);
- if (MAP_FAILED == buffers[n_buffers].start)
- errno_exit("mmap");
- }
- }
- static void init_device(void) {
- struct v4l2_capability cap;
- struct v4l2_cropcap cropcap;
- struct v4l2_crop crop;
- struct v4l2_format fmt;
- unsigned int min;
- if (-1 == xioctl(fd, VIDIOC_QUERYCAP, &cap)) {
- if (EINVAL == errno) {
- fprintf(stderr, "%s is no V4L2 device\n", dev_name);
- exit(EXIT_FAILURE);
- } else {
- errno_exit("VIDIOC_QUERYCAP");
- }
- }
- if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
- fprintf(stderr, "%s is no video capture device\n", dev_name);
- exit(EXIT_FAILURE);
- }
- /* Select video input, video standard and tune here. */
- CLEAR (cropcap);
- cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- if (0 == xioctl(fd, VIDIOC_CROPCAP, &cropcap)) {
- crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- crop.c = cropcap.defrect; /* reset to default */
- if (-1 == xioctl(fd, VIDIOC_S_CROP, &crop)) {
- switch (errno) {
- case EINVAL:
- /* Cropping not supported. */
- break;
- default:
- /* Errors ignored. */
- break;
- }
- }
- } else {
- /* Errors ignored. */
- }
- 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_YUYV;
- fmt.fmt.pix.field = V4L2_FIELD_ANY;
- if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt))
- errno_exit("VIDIOC_S_FMT");
- /* Note VIDIOC_S_FMT may change width and height. */
- /* Buggy driver paranoia. */
- min = fmt.fmt.pix.width * 2;
- if (fmt.fmt.pix.bytesperline < min)
- fmt.fmt.pix.bytesperline = min;
- min = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
- if (fmt.fmt.pix.sizeimage < min)
- fmt.fmt.pix.sizeimage = min;
- init_mmap();
- }
- static void close_device(void) {
- if (-1 == close(fd))
- errno_exit("close");
- fd = -1;
- }
- static void open_device(void) {
- struct stat st;
- if (-1 == stat(dev_name, &st)) {
- fprintf(stderr, "Cannot identify '%s': %d, %s\n", dev_name, errno,
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- if (!S_ISCHR (st.st_mode)) {
- fprintf(stderr, "%s is no device\n", dev_name);
- exit(EXIT_FAILURE);
- }
- fd = open(dev_name, O_RDWR /* required */| O_NONBLOCK, 0);
- if (-1 == fd) {
- fprintf(stderr, "Cannot open '%s': %d, %s\n", dev_name, errno,
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- }
- int main(int argc, char ** argv) {
- dev_name = "/dev/video0";
- open_device();
- init_device();
- start_capturing();
- mainloop();
- uninit_device();
- close_device();
- exit(EXIT_SUCCESS);
- return 0;
- }
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