v4l2视频采集程序

 

/*
 *  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>
 
#define CLEAR(x) memset (&(x), 0, sizeof (x))
 
typedef enum {
        IO_METHOD_READ,
        IO_METHOD_MMAP,
        IO_METHOD_USERPTR,
} io_method;
 
struct buffer {
        void *                  start;
        size_t                  length;
};
 
static char * dev_name   = NULL;
static io_method  io = IO_METHOD_MMAP;
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,int len)
{
                unsigned short int *rep;
 rep=(unsigned short int *)p;
  int i=0,bits_per_pixel =16;                     
 int line_x =line_y = 0;
 int xres=600;
                int InfoHead.ciHeight=480;
 //向framebuffer中写BMP图片
 int ftp=open("/dev/fb0",O_RDWR);
 printf("ftp:%d\n",ftp);
 while(!feof(p))
 {
  PIXEL *pix;
    unsigned short int tmp;
  //rc = fread( (char *)&pix, 1, sizeof(unsigned short int), fp);
  //if (rc != sizeof(unsigned short int))
  //{
  // break;
  //}
  pix=*(rep+i++);
  location = line_x * bits_per_pixel / 8 + (InfoHead.ciHeight - line_y - 1) * xres * bits_per_pixel / 8;

  //显示每一个像素
  tmp=pix.red<<0 | pix.green<<5 | pix.blue<<11;
  *((unsigned short int*)(ftp + location)) = tmp;

  line_x++;
  if (line_x == InfoHead.ciWidth )
  {
   line_x = 0;
   line_y++;

   if(line_y == InfoHead.ciHeight)
   {
    break;
   }
  }
 }

        printf("len:%d\n",len);
        fputc ('.', stdout);
        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,buffers[buf.index].length);
 
                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,);
              if (-1 == xioctl (fd, VIDIOC_QBUF, &buf))
                      errno_exit ("VIDIOC_QBUF");
              break;
      }
      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 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 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 = 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;
        unsigned int page_size;
 
        page_size = getpagesize ();
        buffer_size = (buffer_size + page_size - 1) & ~(page_size - 1);
 
        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/o\n", 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 = memalign (/* boundary */ page_size,
                                                     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;
    fmt.fmt.pix.width       = 600; 
    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. */
    /* 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 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);
        }
}
 
static void usage (FILE *fp,    int   argc, char ** argv)
{
        fprintf (fp,
                 "Usage: %s [options]\n\n"
                 "Options:\n"
                 "-d | --device name   Video device name [/dev/video]\n"
                 "-h | --help          Print this message\n"
                 "-m | --mmap          Use memory mapped buffers\n"
                 "-r | --read          Use read() calls\n"
                 "-u | --userp         Use application allocated buffers\n"
                 "",
                 argv[0]);
}
 
static const char short_options [] = "d:hmru";
 
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' },
        { 0, 0, 0, 0 }
};
 

int main(int argc,  char **  argv)
{
        dev_name = "/dev/video0";
        for (;;)
 {
                int index;
                int c;   
                c = getopt_long (argc, argv, short_options, long_options,  &index); 
                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;
               default:
                       usage (stderr, argc, argv);
                       exit (EXIT_FAILURE);
               }
       }
       open_device();
       init_device();
       start_capturing();
       mainloop();
       stop_capturing();
       uninit_device();
       close_device();
       exit(EXIT_SUCCESS);
       return 0;
 }