V4L(Video for Linux)使用摄像头实验笔记(3)

我验证了一下这个解决方法。

把v4l.h头文件修改为v4l2.h，v4l2.h如下

#ifndef _V4L2_H_
#define _V4L2_H_

#include <stdio.h>
#include <stdlib.h> //stdio.h and stdlib.h are needed by perror function
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h> //O_RDWR
#include <unistd.h>
#include <sys/mman.h> //unistd.h and sys/mman.h are needed by mmap function
#include <stdbool.h>//false and true
#include <sys/ioctl.h>
#include <linux/videodev2.h>//v4l2 API

typedef struct _v4l2_struct
{
 int fd;
 struct v4l2_capability capability;
}v4l2_device;

extern int v4l2_open(char*,v4l2_device*);
extern int v4l2_close(v4l2_device*);
extern int v4l2_get_capability(v4l2_device*);

#define DEFAULT_DEVICE "/dev/video0"
int v4l2_open(char *dev,v4l2_device *vd)
{
 if(!dev)
 dev=DEFAULT_DEVICE;
 if((vd->fd=open(dev,O_RDWR))<0)
 {
  perror("v4l2_open fail");
  return -1;
 }
 if(v4l2_get_capability(vd))
  return -1;
 printf("video capture device name:%s\n",vd->capability.driver);
 return 0;
}

int v4l2_close(v4l2_device *vd)
{
 close(vd->fd);
 return 0;
}

int v4l2_get_capability(v4l2_device *vd)
{
 if(ioctl(vd->fd,VIDIOC_QUERYCAP,&vd->capability)<0)
 { 
  perror("v4l2_get_capability fail");
  return -1;
 }
 return 0; 
}

#endif

把测试程序app-camera.c改为test.c，test.c如下

#include "v4l2.h"

v4l2_device vd;

void main()
{
 v4l2_open(DEFAULT_DEVICE,&vd);
 v4l2_close(&vd);
}

运行结果如图7所示。

图7

我得到了我想要的结果。