基于V4L2摄像头采集图片程序设计

#ifndef __COMMON_H
#define __COMMON_H
//该头文件定义的是摄像头在屏幕上显示的宽度和高度
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<errno.h>
#include <stdint.h>

typedef unsigned char U8;
typedef unsigned int U32;
typedef unsigned short U16;

#define WIDTH  800
#define HEIGHT 600

#endif	//__COMMON_H

#ifndef __VIDEOCAPTURE_H
#define __VIDEOCAPTURE_H

#include"common.h"
#include<sys/mman.h>
#include<fcntl.h>
#include<linux/videodev2.h>

#define VIDEODEVNAME ("/dev/video0")
#define COUNT  4
//需要调用的摄像头相关的接口，包括初始化，开始，结束，采取一帧的数据并保存
int initCamera();
void unInitCamera();
int startCamera();
int stopCamera();
int getOneFrame(U8* pcYuvBuffer);

#endif	//__VIDEOCAPTURE_H

#include"videoCapture.h"

static U8* pcYuv[COUNT]={NULL};
static int vidDevFd = -1;
static int nLength = 0;
static struct v4l2_buffer dequeBuffer;
static struct v4l2_buffer queueBuffer;

//初始化摄像头程序
int initCamera()
{
	//open /dev/video*
	//open video device
	vidDevFd = open(VIDEODEVNAME, O_RDONLY);
	if (vidDevFd < 0)
	{
		fprintf(stderr, "open %s failed %s\n",VIDEODEVNAME, strerror(errno));
		return -1;
	}

	//printf("vidDevFd = %d!\n", vidDevFd);			

	//设置视频格式
	//set video device format
	struct v4l2_format vidDevFmt;
	vidDevFmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	vidDevFmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
	vidDevFmt.fmt.pix.width = WIDTH;
	vidDevFmt.fmt.pix.height = HEIGHT;

	if (0 != ioctl(vidDevFd, VIDIOC_S_FMT, &vidDevFmt))
	{
		fprintf(stderr, "VIDIOC_S_FMT failed %s\n", strerror(errno));
		unInitCamera();
		return -1;
	}

	//request buffers
	//max count need to be considered
	struct v4l2_requestbuffers reqBuffer;
	reqBuffer.count = COUNT;
	reqBuffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	reqBuffer.memory = V4L2_MEMORY_MMAP;

	if (0 != ioctl(vidDevFd, VIDIOC_REQBUFS, &reqBuffer))
	{
		fprintf(stderr, "VIDIOC_REQBUFS failed %s\n", strerror(errno));
		unInitCamera();
		return -1;
	}

	//query buffers
	int i = 0;
	struct v4l2_buffer qryBuffer;
	qryBuffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	qryBuffer.memory = V4L2_MEMORY_MMAP;

	for (i = 0; i < COUNT; i++)
	{
		qryBuffer.index = i;

		if (0 != ioctl(vidDevFd, VIDIOC_QUERYBUF, &qryBuffer))
		{
			fprintf(stderr, "VIDIOC_QUERYBUF failed %s\n", strerror(errno));
			unInitCamera();
			return -1;
		}

		printf("qryBuffer.m.offset=%d, qryBuffer.lenght=%d\n", qryBuffer.m.offset, qryBuffer.length);
		//mmap video device memory allocated by VIDIOC_REQBUFS
		pcYuv[i] = mmap(NULL, qryBuffer.length, PROT_READ, MAP_SHARED, vidDevFd, qryBuffer.m.offset);
		nLength = qryBuffer.length;

		//queue buffers
		struct v4l2_buffer queBuffer;
		queBuffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		queBuffer.memory = V4L2_MEMORY_MMAP;
		queBuffer.index = qryBuffer.index;
		if (0 != ioctl(vidDevFd, VIDIOC_QBUF, &queBuffer))
		{
			fprintf(stderr, "init VIDIOC_QBUF failed %s\n", strerror(errno));
			unInitCamera();
			return -1;
		}

	}

	dequeBuffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	dequeBuffer.memory = V4L2_MEMORY_MMAP;
	queueBuffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	queueBuffer.memory = V4L2_MEMORY_MMAP;

	return 0;
}

//取消摄像头
void unInitCamera()
{
	int i = 0;

	for (i = 0; i < COUNT; i++)
	{
		if (NULL != pcYuv[i])
		{
			if (-1 == munmap(pcYuv[i], nLength));
			{
				//fprintf(stderr,"munmap error:%s!\n",strerror(errno));
			}
			pcYuv[i] = NULL;
		}
	}

	if (vidDevFd >= 0)
		close(vidDevFd);
}
//摄像头开始
int startCamera()
{
	//start camera		

	int nArg = 1;
	if (0 != ioctl(vidDevFd, VIDIOC_STREAMON, &nArg))
	{
		fprintf(stderr, "VIDIOC_STREAMON failed %s\n", strerror(errno));
		unInitCamera();
		return -1;
	}

	return 0;
}

//停止摄像头
int stopCamera()
{
	//stop camera		

	int nArg = 1;
	if (0 != ioctl(vidDevFd, VIDIOC_STREAMOFF, &nArg))
	{
		fprintf(stderr, "VIDIOC_STREAMOFF failed %s\n", strerror(errno));
		unInitCamera();
		return -1;
	}

	return 0;
}

//获取Frame
int getOneFrame(unsigned char* pcYuyvBuffer)
{
	if (0 != ioctl(vidDevFd, VIDIOC_DQBUF, &dequeBuffer))
	{
		fprintf(stderr, "VIDIOC_DQBUF failed %s\n", strerror(errno));
		unInitCamera();
		return -1;
	}

	//get frame
	memcpy(pcYuyvBuffer, pcYuv[dequeBuffer.index], dequeBuffer.length);
	printf("len=%d\n",dequeBuffer.length);

	//queue
	queueBuffer.index = dequeBuffer.index;
	if (0 != ioctl(vidDevFd, VIDIOC_QBUF, &queueBuffer))
	{
		fprintf(stderr, "VIDIOC_QBUF failed %s\n", strerror(errno));
		unInitCamera();
		return -1;
	}
	return 0;
}

#include"videoCapture.h"

int main(void )
{
	int nRet = 0;
	//char yuyv[WIDTH*HEIGHT*2];
	char* pcYuvBuffer = NULL; 

	if(-1 == initCamera())
	{
		printf("initCamera failed!\n");
		goto ERR;
	}

	if (-1 == startCamera())
	{
		printf("startCamera failed!\n");
		goto ERR;
	}

	pcYuvBuffer = (char*)malloc((WIDTH*HEIGHT*2)*sizeof(char));
	if (NULL == pcYuvBuffer)
	{
		printf("malloc YUYV buffer failed!\n");
		goto ERR;
	}

	int nDstFd = open("mytest.yuv", O_CREAT|O_EXCL|O_RDWR|O_TRUNC, 0777);
	if (nDstFd == -1)
	{
		fprintf(stderr, "open mytest.yuv failed:%s\n", strerror(errno));
	}

	int nFrameNum = 0;

	while(1)
	{
		if (20 == nFrameNum)
			break;

		memset(pcYuvBuffer, 0, WIDTH*HEIGHT*2);

		//if (-1 == getOneFrame(yuyv))
		if (-1 == getOneFrame(pcYuvBuffer))
		{
			printf("getOneFrame error!\n");
			goto ERR;
		}

		//if (-1 == write(nDstFd, yuyv, WIDTH*HEIGHT*2))
		if (-1 == write(nDstFd, pcYuvBuffer, WIDTH*HEIGHT*2))
		{
			fprintf(stderr, "write error:%s\n", strerror(errno));
			goto ERR;
		}

		nFrameNum++;
	}

	if (-1 == stopCamera())
	{
		printf("stopCamera error!\n");
	}

ERR:
	if (NULL != pcYuvBuffer)
	{
		free(pcYuvBuffer);
		pcYuvBuffer = NULL;
	}

	unInitCamera();

	close(nDstFd);
	nDstFd = -1;

	return 0;
}