Linux下V4L2拍照测试用例

一、源码test.c

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#include <fcntl.h>

#include <stdlib.h>

#include <sys/mman.h>

#include <linux/videodev2.h>

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