C语言高级应用---操作linux下V4L2摄像头应用程序

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include "j-yuv.h"
#include "CameralOpt.h"
#include "FrameBufferOpt.h"

#define    WIDTH   640
#define    HIGHT   480

int main(void)
{
	char yuyv[WIDTH*HIGHT*2];
	char bmp[WIDTH*HIGHT*3];

//	set_bmp_header((struct bmp_header_t *)bmp, WIDTH, HIGHT);
	//初始化摄像头
	Init_Cameral(WIDTH , HIGHT );
	//初始化framebuffer
	Init_FrameBuffer(WIDTH , HIGHT ); 

	//开启摄像头
	Start_Cameral();
	//采集一张图片
	int count = 0 ; 
	while(1)
	{
		Get_Picture(yuyv);
		yuyv2rgb24(yuyv, bmp, WIDTH, HIGHT);
		Write_FrameBuffer(bmp);
//		printf("count:%d \n" , count++);
	}
	//关闭摄像头
	Stop_Cameral();
	//关闭Framebuffer
	Exit_Framebuffer();
	//退出
	Exit_Cameral();
	
	return 0;
}

#ifndef __JYUV_H
#define __JYUV_H

typedef unsigned char  u8;
typedef unsigned short u16;
typedef unsigned int   u32;

#pragma pack(1)
//定义bmp头
struct bmp_header_t{
    u16        magic;
    u32       file_size;
    u32       RESERVED1;
    u32       offset;         //54 bytes 表示54个偏移量

    u32       head_num;    //40
    u32       width;
    u32       height;
    u16       color_planes; //1
    u16       bit_count;
    u32       bit_compression; //0
    u32       image_size; //except the size of header
    u32       h_resolution;
    u32       v_resolution;
    u32       color_num;
    u32       important_colors;
};

#pragma pack()

void set_bmp_header(struct bmp_header_t * header, u32 width, u32 height);
int yuyv2rgb24(u8 *yuyv, u8 *rgb, u32 width, u32 height);

#endif /* __JYUV_H */ 

#include "j-yuv.h"

#define BIT_COUNT   24

void set_bmp_header(struct bmp_header_t *header, u32 width, u32 height)
{
    header->magic = 0x4d42;
    header->image_size = width * height * BIT_COUNT/8;
    header->file_size = header->image_size + 54;
    header->RESERVED1 = 0;
    header->offset = 54;

    header->head_num = 40;
    header->width = width;
    header->height = height;
    header->color_planes = 1;
    header->bit_count = BIT_COUNT;
    header->bit_compression = 0;
    header->h_resolution = 0;
    header->v_resolution = 0;
    header->color_num = 0;
    header->important_colors = 0;
}
//yuyv转rgb24的算法实现
int yuyv2rgb24(u8 *yuyv, u8 *rgb, u32 width, u32 height)
{
    u32 i, in, rgb_index = 0;
    u8 y0, u0, y1, v1;
    int r, g, b;
    u32 out = 0, x, y;
 
    for(in = 0; in < width * height * 2; in += 4)
    {
	y0 = yuyv[in+0];
	u0 = yuyv[in+1];
	y1 = yuyv[in+2];
	v1 = yuyv[in+3];

	for (i = 0; i < 2; i++)
	{
		if (i)
			y = y1;
		else
			y = y0;	
		r = y + (140 * (v1-128))/100;  //r
		g = y - (34 * (u0-128))/100 - (71 * (v1-128))/100; //g
 		b = y + (177 * (u0-128))/100; //b
		if(r > 255)   r = 255;
        	if(g > 255)   g = 255;
        	if(b > 255)   b = 255;
       		if(r < 0)     r = 0;
        	if(g < 0)     g = 0;
	        if(b < 0)     b = 0;

		y = height - rgb_index/width -1;
		x = rgb_index%width;
		rgb[(y*width+x)*3+0] = b;
		rgb[(y*width+x)*3+1] = g;
		rgb[(y*width+x)*3+2] = r;
		rgb_index++;
	}
    }
    return 0;
}

#include "FrameBufferOpt.h"

static int Frame_fd ; 
static int *FrameBuffer = NULL ; 
static int W , H ;

//初始化framebuffer
int Init_FrameBuffer(int Width , int Higth)
{
	W = Width ; 
	H = Higth ; 
	Frame_fd = open("/dev/fb" , O_RDWR);
	if(-1 == Frame_fd)
	{
		perror("open frame buffer fail");
		return -1 ; 
	}

//根本就不用CPU搬运   用DMA做为搬运工
FrameBuffer = mmap(0, 1280*1024*4 , PROT_READ | PROT_WRITE , MAP_SHARED , Frame_fd ,0 );
	if(FrameBuffer == (void *)-1)
	{
		perror("memory map fail");
		return -2 ;
	}
	return 0 ; 
}

//写入framebuffer
int Write_FrameBuffer(const char *buffer)
{
	int row  , col ; 
	char *p = NULL ; 
	for(row = 0 ; row <1024 ; row++)
	{
		for(col = 0 ; col < 1280 ;  col++)
		{
			if((row < H)  && (col < W))
			{
				p = (char *)(buffer + (row * W+ col ) * 3); 
				FrameBuffer[row*1280+col] = RGB((unsigned char)(*(p+2)),(unsigned char)(*(p+1)),(unsigned char )(*p));
			}
		}
	}
	return 0 ; 
}

//退出framebuffer
int Exit_Framebuffer(void)
{
	munmap(FrameBuffer ,  W*H*4);
	close(Frame_fd);
	return 0 ; 
}

#ifndef  _FRAMEBUFFEROPT_H
#define  _FRAMEBUFFEROPT_H

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>


#define    RGB(r,g,b)		((r<<16)|(g<<8)|b)

//初始化ramebuffer
int Init_FrameBuffer(int Width , int Higth);

//写数据到framebuffer
int Write_FrameBuffer(const char *buffer);

//退出framebuffer
int Exit_Framebuffer(void);



#endif //_FRAMEBUFFEROPT_H

#ifndef  _CAMERALOPT_H
#define  _CAMERALOPT_H

#include <stdio.h>
#include <linux/videodev2.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>

#define   COUNT  3
//初始化摄像头
int Init_Cameral(int Width , int Hight);
int Exit_Cameral(void); //退出摄像头
//摄像头开始采集
int Start_Cameral(void);
int Stop_Cameral(void);//停止摄像头
//获取摄像头的数据
int Get_Picture(char *buffer);

#endif  //_CAMERALOPT_H

#include "CameralOpt.h"
int video_fd ; 
int length ; 
char *yuv[COUNT] ; 
struct v4l2_buffer  enqueue  , dequeue ;  //定义出入队的操作结构体成员

int Init_Cameral(int Width , int Hight)
{
	//参数检查
	char *videodevname = NULL ; 
	videodevname = "/dev/video0" ; 
	
	//打开设备
	video_fd = open(videodevname , O_RDWR);
	if(-1 == video_fd )
	{
		perror("open video device fail");
		return -1 ; 
	}

	int i ; 
	int ret ; 
	struct v4l2_format  format ; 
	format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE ; 
	format.fmt.pix.width  = Width; 
	format.fmt.pix.height = Hight; 
	format.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV ;  //我支持的格式是这个

	ret = ioctl(video_fd , VIDIOC_S_FMT , &format);
	if(ret != 0)
	{
		perror("set video format fail");
		return -2 ; 
	}


	//申请buffer,切割成几个部分
	//3
	struct v4l2_requestbuffers  requestbuffer ; 
	requestbuffer.count = COUNT ; 
	requestbuffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE ; 
	requestbuffer.memory = V4L2_MEMORY_MMAP ; 

	ret = ioctl(video_fd , VIDIOC_REQBUFS , &requestbuffer);
	if(ret != 0)
	{
		perror("request buffer fail ");
		return -3  ;
	}
	
	
	//querybuffer
	struct v4l2_buffer querybuffer ; 
	querybuffer.type =  V4L2_BUF_TYPE_VIDEO_CAPTURE ; 
	querybuffer.memory = V4L2_MEMORY_MMAP ; 

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

		ret = ioctl(video_fd , VIDIOC_QUERYBUF , &querybuffer);
		if(ret != 0)
		{
			perror("query buffer fail");
			return -4 ; 
		}
	
//		printf("index:%d length:%d  offset:%d \n" , 
//		querybuffer.index , querybuffer.length , querybuffer.m.offset);
		length = querybuffer.length ; 

		//将摄像头内存印射到进程的内存地址
		yuv[i] = mmap(0,querybuffer.length , PROT_READ | PROT_WRITE , MAP_SHARED , video_fd , querybuffer.m.offset );


		//列队
		
		struct v4l2_buffer  queuebuffer ; 
		queuebuffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE ; 
		queuebuffer.memory =  V4L2_MEMORY_MMAP ; 
		queuebuffer.index = i ; 	

		ret = ioctl(video_fd , VIDIOC_QBUF , &queuebuffer);
		if(ret != 0)
		{
			perror("queuebuffer fail");
			return -5 ; 
		}
	}
	//初始化入队出队
	enqueue.type = V4L2_BUF_TYPE_VIDEO_CAPTURE ; 
	dequeue.type = V4L2_BUF_TYPE_VIDEO_CAPTURE ; 
	enqueue.memory = V4L2_MEMORY_MMAP ; 
	dequeue.memory = V4L2_MEMORY_MMAP ; 

	return 0 ; 
}

int Exit_Cameral(void)
{
	int i ; 
	for(i = 0 ; i < COUNT ; i++)
		munmap(yuv+i , length);
	close(video_fd);
	return 0 ; 
}

int Start_Cameral(void)
{
	//开启摄像头
	int ret ; 
	int on = 1 ; 
	ret = ioctl(video_fd , VIDIOC_STREAMON , &on);
	if(ret != 0)
	{
		perror("start Cameral fail");
		return -1 ; 
	}
	return 0 ; 
}
int Stop_Cameral(void)
{
	//停止摄像头
	int ret ; 
	int off= 1 ; 
	ret = ioctl(video_fd , VIDIOC_STREAMOFF, &off);
	if(ret != 0)
	{
		perror("stop Cameral fail");
		return -1 ; 
	}
	return 0 ;
}

int Get_Picture(char *buffer)
{
	int ret ; 
	//出队
	ret = ioctl(video_fd , VIDIOC_DQBUF , &dequeue);
	if(ret != 0)
	{
		perror("dequeue fail");
		return -1 ; 
	}

	//获取图片数据 YUV   yuv[dequeue.index]
	memcpy(buffer , yuv[dequeue.index] , dequeue.length);
//	write(yuyv_fd , yuv[dequeue.index] , dequeue.length);

	enqueue.index = dequeue.index ; 
	ret = ioctl(video_fd , VIDIOC_QBUF , &enqueue);
	if(ret != 0)
	{
		perror("enqueue fail");
		return -2 ; 
	}
	return 0 ; 
}