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

  1 #include <stdio.h>
  2 #include <string.h>
  3 #include <errno.h>
  4  
  5 #include <sys/types.h>
  6  #include <sys/stat.h>
  7  #include <fcntl.h>
  8  
  9 #include <linux/videodev2.h>
 10  //#include <linux/videodev.h>
 11  #include <libv4l1-videodev.h>  
 12 
 13  /*
 14    0 -- 不是v4l设备
 15    1 -- v4l 设备
 16    2 -- v4l2 设备
 17  */
 18  int test_v4l_version(int fd)
 19  {
 20     int ret = 0;
 21     char dummy[256]; 
 22 
 23     if (-1 != ioctl(fd,VIDIOC_QUERYCAP,dummy)) {
 24          ret = 2;
 25      }
 26    
 27      else if (-1 != ioctl(fd,VIDIOCGCAP,dummy)) {
 28  
 29         ret = 1;
 30      }
 31  
 32     return ret;
 33  }
 34  
 35  int v4l_open(char *dev, v4l_device *vd)
 36  {
 37  if (!dev)
 38  dev = ”/dev/video0”;
 39  if ((vd ->fd = open(dev, O_RDWR)) < 0) {
 40  perror("v4l_open:");
 41  return -1;
 42  }
 43  if (v4l_get_capability(vd))
 44  return -1;
 45  if (v4l_get_picture(vd))
 46  retu rn -1;
 47  return 0;
 48  }
 49  
 50  int v4l_get_capability(v4l_device *vd)
 51  {
 52  if (ioctl(vd ->fd, VIDIOCGCAP, &(vd->capability)) < 0) {
 53  perror("v4l_get_capability:");
 54  return -1;
 55  }
 56  return 0;
 57  }
 58  
 59 
 60 int main(int argc,char * argv[])
 61  {
 62     char dev_name[64] = "/dev/video0";
 63     int cam_fd =-1;
 64  
 65    if(argc>1)
 66         {
 67          strncpy(dev_name,argv[1],sizeof(dev_name)-1);
 68         }
 69  
 70    printf("open device %s\n",dev_name);
 71      cam_fd = open(dev_name,O_RDWR|O_NONBLOCK);
 72  
 73     if(cam_fd == -1)
 74          {
 75           printf("open failure \n");
 76           return -1;
 77          }
 78  
 79    switch(test_v4l_version(cam_fd))
 80         {
 81         case 0:
 82          printf("%s:fd %d isn't v4l deivce\n",dev_name,cam_fd);
 83          return -1;
 84          break;
 85      case 1:
 86          printf("\n### video4linux device info [%s] ###\n",dev_name); 
 87         return -2;
 88          break;
 89      case 2:
 90          printf("\n### v4l2 device info [%s] ###\n",dev_name);
 91          break;
 92         }
 93      
 94  
 95     
 96    
 97      close(cam_fd);
 98  
 99    return 0;
100      
101  }

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