基于Linux的摄像头采集v4l2

来源：互联网发布：美工多少钱一个月编辑：程序博客网时间：2024/04/29 09:29

集体的源码如下：

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <assert.h>#include <getopt.h>           #include <fcntl.h>            #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>        #include <linux/videodev2.h>  struct buffer {        void *                  start;        size_t                  length;}; struct buffer *buffers;unsigned long  n_buffers;unsigned long file_length;int file_fd;char *dev_name = "/dev/video3";int fd;static int read_frame (void){     struct v4l2_buffer buf;          /*帧出列*/     buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;     buf.memory = V4L2_MEMORY_MMAP;     ioctl (fd, VIDIOC_DQBUF, &buf);     write(file_fd,buffers[buf.index].start,buffers[buf.index].length);          /*buf入列*/     ioctl(fd, VIDIOC_QBUF, &buf);     return 1;} int main (int argc,char ** argv){     struct v4l2_capability cap;     struct v4l2_format fmt;     struct v4l2_requestbuffers req;     struct v4l2_buffer buf;      unsigned int i;     enum v4l2_buf_type type;               file_fd = open("test.jpg", O_RDWR | O_CREAT, 0777);         fd = open (dev_name, O_RDWR | O_NONBLOCK, 0);     /*获取驱动信息*/      ioctl (fd, VIDIOC_QUERYCAP, &cap);      printf("Driver Name:%s\n Card Name:%s\n Bus info:%s\n\n",cap.driver,cap.card,cap.bus_info);               /*设置图像格式*/     fmt.type                = V4L2_BUF_TYPE_VIDEO_CAPTURE;     fmt.fmt.pix.width       = 320;     fmt.fmt.pix.height      = 240;     fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;     fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;     ioctl (fd, VIDIOC_S_FMT, &fmt) ;           /*申请图像缓冲区*/     req.count               = 4;     req.type                = V4L2_BUF_TYPE_VIDEO_CAPTURE;     req.memory              = V4L2_MEMORY_MMAP;     ioctl (fd, VIDIOC_REQBUFS, &req);             buffers = calloc (req.count, sizeof (*buffers));           for (n_buffers = 0; n_buffers < req.count; ++n_buffers)     {            /*获取图像缓冲区的信息*/           buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;           buf.memory      = V4L2_MEMORY_MMAP;           buf.index       = n_buffers;            ioctl (fd, VIDIOC_QUERYBUF, &buf);                         buffers[n_buffers].length = buf.length;                       // 把内核空间中的图像缓冲区映射到用户空间          buffers[n_buffers].start = mmap (NULL ,    //通过mmap建立映射关系                                        buf.length,                                        PROT_READ | PROT_WRITE ,                                        MAP_SHARED ,                                        fd,                                        buf.m.offset);     }             /*图像缓冲入队*/               for (i = 0; i < n_buffers; ++i)       {               buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;               buf.memory      = V4L2_MEMORY_MMAP;               buf.index       = i;                ioctl (fd, VIDIOC_QBUF, &buf);                      }        //开始捕捉图像数据      type = V4L2_BUF_TYPE_VIDEO_CAPTURE;    ioctl (fd, VIDIOC_STREAMON, &type);   fd_set fds;   FD_ZERO (&fds);   FD_SET (fd, &fds);   select(fd + 1, &fds, NULL, NULL, NULL);      /*读取一幅图像*/   read_frame();   for (i = 0; i < n_buffers; ++i)      munmap (buffers[i].start, buffers[i].length);       close (fd);   close (file_fd);   printf("Camera Done.\n");   return 0;}

主要的框架上面的东西。

这只是一个比较简单的流程，对于实际的操作我们或许可以将摄像头的数据通过主控制器进行处理，然后在通过Framebuffer进行渲染。具体的框图如下：

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