Linux 验证当前 Video0 不否是v4l设备 linux v4l 编程(1) Video 4 Linux 简介

 #include <stdio.h>

 #include <string.h>

 #include <errno.h>

 #include <sys/types.h>

  #include <sys/stat.h>

  #include <fcntl.h>

 #include <linux/videodev2.h>

  //#include <linux/videodev.h>

  #include <libv4l1-videodev.h>  

  /*

    0 -- 不是v4l设备

    1 -- v4l 设备

    2 -- v4l2 设备

  */

  int test_v4l_version(int fd)

  {

     int ret = ;

     char dummy[]; 

     if (- != ioctl(fd,VIDIOC_QUERYCAP,dummy)) {

          ret = ;

      }

      else if (- != ioctl(fd,VIDIOCGCAP,dummy)) {

         ret = ;

      }

     return ret;

  }

  int v4l_open(char *dev, v4l_device *vd)

  {

  if (!dev)

  dev = ”/dev/video0”;

  if ((vd ->fd = open(dev, O_RDWR)) < ) {

  perror("v4l_open:");

  return -;

  }

  if (v4l_get_capability(vd))

  return -;

  if (v4l_get_picture(vd))

  retu rn -;

  return ;

  }

  int v4l_get_capability(v4l_device *vd)

  {

  if (ioctl(vd ->fd, VIDIOCGCAP, &(vd->capability)) < ) {

  perror("v4l_get_capability:");

  return -;

  }

  return ;

  }

 int main(int argc,char * argv[])

  {

     char dev_name[] = "/dev/video0";

     int cam_fd =-;

    if(argc>)

         {

          strncpy(dev_name,argv[],sizeof(dev_name)-);

         }

    printf("open device %s\n",dev_name);

      cam_fd = open(dev_name,O_RDWR|O_NONBLOCK);

     if(cam_fd == -)

          {

           printf("open failure \n");

           return -;

          }

    switch(test_v4l_version(cam_fd))

         {

         case :

          printf("%s:fd %d isn't v4l deivce\n",dev_name,cam_fd);

          return -;

          break;

      case :

          printf("\n### video4linux device info [%s] ###\n",dev_name);

         return -;

          break;

      case :

          printf("\n### v4l2 device info [%s] ###\n",dev_name);

          break;

         }

      close(cam_fd);

    return ;

  }