aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/media/uapi/v4l/capture.c.rst
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/media/uapi/v4l/capture.c.rst')
-rw-r--r--Documentation/media/uapi/v4l/capture.c.rst671
1 files changed, 0 insertions, 671 deletions
diff --git a/Documentation/media/uapi/v4l/capture.c.rst b/Documentation/media/uapi/v4l/capture.c.rst
deleted file mode 100644
index b4652c2351f2..000000000000
--- a/Documentation/media/uapi/v4l/capture.c.rst
+++ /dev/null
@@ -1,671 +0,0 @@
-.. Permission is granted to copy, distribute and/or modify this
-.. document under the terms of the GNU Free Documentation License,
-.. Version 1.1 or any later version published by the Free Software
-.. Foundation, with no Invariant Sections, no Front-Cover Texts
-.. and no Back-Cover Texts. A copy of the license is included at
-.. Documentation/media/uapi/fdl-appendix.rst.
-..
-.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
-
-file: media/v4l/capture.c
-=========================
-
-.. code-block:: c
-
- /*
- * V4L2 video capture example
- *
- * This program can be used and distributed without restrictions.
- *
- * This program is provided with the V4L2 API
- * see https://linuxtv.org/docs.php for more information
- */
-
- #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 <sys/stat.h>
- #include <sys/types.h>
- #include <sys/time.h>
- #include <sys/mman.h>
- #include <sys/ioctl.h>
-
- #include <linux/videodev2.h>
-
- #define CLEAR(x) memset(&(x), 0, sizeof(x))
-
- enum io_method {
- IO_METHOD_READ,
- IO_METHOD_MMAP,
- IO_METHOD_USERPTR,
- };
-
- struct buffer {
- void *start;
- size_t length;
- };
-
- static char *dev_name;
- static enum io_method io = IO_METHOD_MMAP;
- static int fd = -1;
- struct buffer *buffers;
- static unsigned int n_buffers;
- static int out_buf;
- static int force_format;
- static int frame_count = 70;
-
- 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 fh, int request, void *arg)
- {
- int r;
-
- do {
- r = ioctl(fh, request, arg);
- } while (-1 == r && EINTR == errno);
-
- return r;
- }
-
- static void process_image(const void *p, int size)
- {
- if (out_buf)
- fwrite(p, size, 1, stdout);
-
- fflush(stderr);
- fprintf(stderr, ".");
- fflush(stdout);
- }
-
- static int read_frame(void)
- {
- struct v4l2_buffer buf;
- unsigned int i;
-
- switch (io) {
- case IO_METHOD_READ:
- if (-1 == read(fd, buffers[0].start, buffers[0].length)) {
- switch (errno) {
- case EAGAIN:
- return 0;
-
- case EIO:
- /* Could ignore EIO, see spec. */
-
- /* fall through */
-
- default:
- errno_exit("read");
- }
- }
-
- process_image(buffers[0].start, buffers[0].length);
- break;
-
- case IO_METHOD_MMAP:
- 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:
- /* Could ignore EIO, see spec. */
-
- /* fall through */
-
- default:
- errno_exit("VIDIOC_DQBUF");
- }
- }
-
- assert(buf.index < n_buffers);
-
- process_image(buffers[buf.index].start, buf.bytesused);
-
- if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
- errno_exit("VIDIOC_QBUF");
- break;
-
- case IO_METHOD_USERPTR:
- CLEAR(buf);
-
- buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- buf.memory = V4L2_MEMORY_USERPTR;
-
- if (-1 == xioctl(fd, VIDIOC_DQBUF, &buf)) {
- switch (errno) {
- case EAGAIN:
- return 0;
-
- case EIO:
- /* Could ignore EIO, see spec. */
-
- /* fall through */
-
- default:
- errno_exit("VIDIOC_DQBUF");
- }
- }
-
- for (i = 0; i < n_buffers; ++i)
- if (buf.m.userptr == (unsigned long)buffers[i].start
- && buf.length == buffers[i].length)
- break;
-
- assert(i < n_buffers);
-
- process_image((void *)buf.m.userptr, buf.bytesused);
-
- if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
- errno_exit("VIDIOC_QBUF");
- break;
- }
-
- return 1;
- }
-
- static void mainloop(void)
- {
- unsigned int count;
-
- count = frame_count;
-
- 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 stop_capturing(void)
- {
- enum v4l2_buf_type type;
-
- switch (io) {
- case IO_METHOD_READ:
- /* Nothing to do. */
- break;
-
- case IO_METHOD_MMAP:
- case IO_METHOD_USERPTR:
- type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- if (-1 == xioctl(fd, VIDIOC_STREAMOFF, &type))
- errno_exit("VIDIOC_STREAMOFF");
- break;
- }
- }
-
- static void start_capturing(void)
- {
- unsigned int i;
- enum v4l2_buf_type type;
-
- switch (io) {
- case IO_METHOD_READ:
- /* Nothing to do. */
- break;
-
- case IO_METHOD_MMAP:
- 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");
- break;
-
- case IO_METHOD_USERPTR:
- for (i = 0; i < n_buffers; ++i) {
- struct v4l2_buffer buf;
-
- CLEAR(buf);
- buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- buf.memory = V4L2_MEMORY_USERPTR;
- buf.index = i;
- buf.m.userptr = (unsigned long)buffers[i].start;
- buf.length = buffers[i].length;
-
- 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");
- break;
- }
- }
-
- static void uninit_device(void)
- {
- unsigned int i;
-
- switch (io) {
- case IO_METHOD_READ:
- free(buffers[0].start);
- break;
-
- case IO_METHOD_MMAP:
- for (i = 0; i < n_buffers; ++i)
- if (-1 == munmap(buffers[i].start, buffers[i].length))
- errno_exit("munmap");
- break;
-
- case IO_METHOD_USERPTR:
- for (i = 0; i < n_buffers; ++i)
- free(buffers[i].start);
- break;
- }
-
- free(buffers);
- }
-
- static void init_read(unsigned int buffer_size)
- {
- buffers = calloc(1, sizeof(*buffers));
-
- if (!buffers) {
- fprintf(stderr, "Out of memory\\n");
- exit(EXIT_FAILURE);
- }
-
- buffers[0].length = buffer_size;
- buffers[0].start = malloc(buffer_size);
-
- if (!buffers[0].start) {
- fprintf(stderr, "Out of memory\\n");
- exit(EXIT_FAILURE);
- }
- }
-
- 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 mappingn", 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 = 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_userp(unsigned int buffer_size)
- {
- struct v4l2_requestbuffers req;
-
- CLEAR(req);
-
- req.count = 4;
- req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- req.memory = V4L2_MEMORY_USERPTR;
-
- if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req)) {
- if (EINVAL == errno) {
- fprintf(stderr, "%s does not support "
- "user pointer i/on", dev_name);
- exit(EXIT_FAILURE);
- } else {
- errno_exit("VIDIOC_REQBUFS");
- }
- }
-
- buffers = calloc(4, sizeof(*buffers));
-
- if (!buffers) {
- fprintf(stderr, "Out of memory\\n");
- exit(EXIT_FAILURE);
- }
-
- for (n_buffers = 0; n_buffers < 4; ++n_buffers) {
- buffers[n_buffers].length = buffer_size;
- buffers[n_buffers].start = malloc(buffer_size);
-
- if (!buffers[n_buffers].start) {
- fprintf(stderr, "Out of memory\\n");
- exit(EXIT_FAILURE);
- }
- }
- }
-
- 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);
- }
-
- switch (io) {
- case IO_METHOD_READ:
- if (!(cap.capabilities & V4L2_CAP_READWRITE)) {
- fprintf(stderr, "%s does not support read i/o\\n",
- dev_name);
- exit(EXIT_FAILURE);
- }
- break;
-
- case IO_METHOD_MMAP:
- case IO_METHOD_USERPTR:
- if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
- fprintf(stderr, "%s does not support streaming i/o\\n",
- dev_name);
- exit(EXIT_FAILURE);
- }
- break;
- }
-
-
- /* 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;
- if (force_format) {
- fmt.fmt.pix.width = 640;
- fmt.fmt.pix.height = 480;
- fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
- fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
-
- if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt))
- errno_exit("VIDIOC_S_FMT");
-
- /* Note VIDIOC_S_FMT may change width and height. */
- } else {
- /* Preserve original settings as set by v4l2-ctl for example */
- if (-1 == xioctl(fd, VIDIOC_G_FMT, &fmt))
- errno_exit("VIDIOC_G_FMT");
- }
-
- /* 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;
-
- switch (io) {
- case IO_METHOD_READ:
- init_read(fmt.fmt.pix.sizeimage);
- break;
-
- case IO_METHOD_MMAP:
- init_mmap();
- break;
-
- case IO_METHOD_USERPTR:
- init_userp(fmt.fmt.pix.sizeimage);
- break;
- }
- }
-
- 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 devicen", 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);
- }
- }
-
- static void usage(FILE *fp, int argc, char **argv)
- {
- fprintf(fp,
- "Usage: %s [options]\\n\\n"
- "Version 1.3\\n"
- "Options:\\n"
- "-d | --device name Video device name [%s]n"
- "-h | --help Print this messagen"
- "-m | --mmap Use memory mapped buffers [default]n"
- "-r | --read Use read() callsn"
- "-u | --userp Use application allocated buffersn"
- "-o | --output Outputs stream to stdoutn"
- "-f | --format Force format to 640x480 YUYVn"
- "-c | --count Number of frames to grab [%i]n"
- "",
- argv[0], dev_name, frame_count);
- }
-
- static const char short_options[] = "d:hmruofc:";
-
- static const struct option
- long_options[] = {
- { "device", required_argument, NULL, 'd' },
- { "help", no_argument, NULL, 'h' },
- { "mmap", no_argument, NULL, 'm' },
- { "read", no_argument, NULL, 'r' },
- { "userp", no_argument, NULL, 'u' },
- { "output", no_argument, NULL, 'o' },
- { "format", no_argument, NULL, 'f' },
- { "count", required_argument, NULL, 'c' },
- { 0, 0, 0, 0 }
- };
-
- int main(int argc, char **argv)
- {
- dev_name = "/dev/video0";
-
- for (;;) {
- int idx;
- int c;
-
- c = getopt_long(argc, argv,
- short_options, long_options, &idx);
-
- if (-1 == c)
- break;
-
- switch (c) {
- case 0: /* getopt_long() flag */
- break;
-
- case 'd':
- dev_name = optarg;
- break;
-
- case 'h':
- usage(stdout, argc, argv);
- exit(EXIT_SUCCESS);
-
- case 'm':
- io = IO_METHOD_MMAP;
- break;
-
- case 'r':
- io = IO_METHOD_READ;
- break;
-
- case 'u':
- io = IO_METHOD_USERPTR;
- break;
-
- case 'o':
- out_buf++;
- break;
-
- case 'f':
- force_format++;
- break;
-
- case 'c':
- errno = 0;
- frame_count = strtol(optarg, NULL, 0);
- if (errno)
- errno_exit(optarg);
- break;
-
- default:
- usage(stderr, argc, argv);
- exit(EXIT_FAILURE);
- }
- }
-
- open_device();
- init_device();
- start_capturing();
- mainloop();
- stop_capturing();
- uninit_device();
- close_device();
- fprintf(stderr, "\\n");
- return 0;
- }
generated by cgit 1.2.3-korg (git 2.39.0) at 2024-04-25 06:39:04 +0000