Linux下V4L2拍照测试用例

一、源码test.c

 #include
 #include
 #include
 #include

 int main(){
   //////
   int fd = open("/dev/video0",O_RDWR);
   printf("TK------->>>fd is %d\n",fd);
   //////
   struct v4l2_capability cap;
   ioctl(fd,VIDIOC_QUERYCAP,&cap);
   printf("TK---------->>>>>Driver Name:%s\nCard Name:%s\nBus info:%s\n",cap.driver,cap.card,cap.bus_info);
   //////
   struct v4l2_fmtdesc fmtdesc;
   fmtdesc.index = 0; fmtdesc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
   while(ioctl(fd,VIDIOC_ENUM_FMT,&fmtdesc) != -1){
    printf("TK-------->>>>>fmtdesc.description is %s\n",fmtdesc.description);
    fmtdesc.index ++;
   }
   //////
   struct v4l2_format fmt;
   fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
   ioctl(fd,VIDIOC_G_FMT,&fmt);
   printf("TK----------->>>>>fmt.fmt.width is %d\nfmt.fmt.pix.height is %d\nfmt.fmt.pix.colorspace is %d\n",fmt.fmt.pix.width,fmt.fmt.pix.height,fmt.fmt.pix.colorspace);
   //////
   struct v4l2_requestbuffers req;
   req.count = 4;
   req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
   req.memory = V4L2_MEMORY_MMAP;
   ioctl(fd,VIDIOC_REQBUFS,&req);
   struct buffer{
     void *start;
     unsigned int length;
   }*buffers;
   buffers = (struct buffer*)calloc (req.count, sizeof(*buffers));
   unsigned int n_buffers = 0;
   for(n_buffers = 0; n_buffers < req.count; ++n_buffers){
     struct v4l2_buffer buf;
     memset(&buf,0,sizeof(buf));
     buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
     buf.memory = V4L2_MEMORY_MMAP;
     buf.index = n_buffers;
     if(ioctl(fd,VIDIOC_QUERYBUF,&buf) == -1){
       printf("TK---------_>>>>>>error\n");
       close(fd);
       exit(-1);
     }
     buffers[n_buffers].length = buf.length;
     buffers[n_buffers].start = mmap(NULL,buf.length,PROT_READ|PROT_WRITE,MAP_SHARED,fd,buf.m.offset);
     if(MAP_FAILED == buffers[n_buffers].start){
       printf("TK--------__>>>>>error 2\n");
       close(fd);
       exit(-1);
     }
   }
   ////
   unsigned int i;
   enum v4l2_buf_type type;
   for(i = 0; i < 4; i++){
     struct v4l2_buffer buf;
     buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
     buf.memory = V4L2_MEMORY_MMAP;
     buf.index = i;
     ioctl(fd,VIDIOC_QBUF,&buf);
   }
   type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
   ioctl(fd,VIDIOC_STREAMON,&type);
   ////
   struct v4l2_buffer buf;
   buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
   buf.memory = V4L2_MEMORY_MMAP;
   ioctl(fd,VIDIOC_DQBUF,&buf);
   char path[20];
   snprintf(path,sizeof(path),"./yuyv%d",buf.index);
   int fdyuyv = open(path,O_WRONLY|O_CREAT,00700);
   printf("TK--------->>>>fdyuyv is %d\n",fdyuyv);
   int resultyuyv = write(fdyuyv,buffers[buf.index].start,1280*720*2);
   printf("TK--------->>>resultyuyv is %d\n",resultyuyv);
   close(fdyuyv);
   ////
   close(fd);
   return 0;
 }

二、编译运行

gcc test.c -o rest

./test

三、结果

在本目录下生成yuyv0这样一个文件，是jpeg编码后的文件。

四、极力推荐一款window下的图像查看工具YUVviewerPlus

  该工具可以将原始yuyv（如yuv422选择yuy2，需要后缀改为.yuv），rgb（rgb24选择gbmp24，需要后缀改为.bmp）等数据文件显示出来。

  另外说明：yuyv和jpeg数据大小为width*height*2；rgb为width*height*3；单位为Bytes。

  附免费下载地址：http://download.csdn.net/detail/tankai19880619/6617647