cam.cpp

一个linux下的摄像头编程

#include "cam.h"

// include other stuff

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#define CONV(a) (a) < 0 ? 0 : (a) > 255 ? 255 : a

CCamera :: CCamera()
{
	;
}

CCamera::~CCamera()
{
	;
}

bool CCamera :: connect(int i)
{

	char videofile[14] = "/dev/video";
	char buff[2];
	sprintf(buff,"%i",i);
	strcat(videofile,buff);

	printf("connecting to videodevice %s\n",videofile);
	cam_fd = open(videofile, O_RDONLY);
    if (ioctl(cam_fd, VIDIOCGCAP, &vcap) < 0)
	{
		printf("failed to connect");
		return false;
	}
	else
	{
		int type;
		if (sscanf(vcap.name, "Philips %d webcam", &type) < 1)
     		{
			printf("No Philips webcam detected.\n");
			return false;
		}
   		else
     		{	
				printf("Philips webcam type %d detected.\n", type);
              float bpp = 1.5;
				ioctl(cam_fd, VIDIOCGWIN, &vwin);           	
    		   camsize = cvSize(vwin.width,vwin.height);
				printf("initial camera size%i %i\n", vwin.width,vwin.height);
				buffer = (char*)malloc((int)(vwin.width * vwin.height * bpp));
				printf("camera memory buffer created\n");
				return true;
		}
	}


}

void CCamera :: disconnect()
{
	close(cam_fd);
}

/*
inline char fix(int a)
{
	if(a < 0) return 0;
	else if(a > 255) return 255;
	     else return (a);
}

// slow but easy to follow
void CCamera :: capture(IplImage* img)
{
   int w = camsize.width;
	int h = camsize.height;

	int wh = w * h;
	float wh54 = (w * h * 5.0) / 4.0;
   int length = (int)(w *  h * 1.5 );
 	read(cam_fd, buffer, length);
	
	char* src = img->imageData;
   for(int y = 0; y < img->height; y++, src += img->widthStep )
     	for(int x = 0; x < img->width; x++ )
			{
				int Uj = (y+1)/2;

				unsigned char Y = buffer[y * w + x];
			 	unsigned char U = buffer[(int)(wh + (Uj * w + x) / 2)];
				unsigned char V = buffer[(int)(wh54 + (Uj * w + x) / 2)];



	          	src[x * img->nChannels] = fix(Y + (1.7 * (U -128))); // B;
				src[x * img->nChannels + 1] = fix(Y - (0.7 * (V-128)) - (0.34 * (U-128))); // G;
				src[x * img->nChannels + 2] = fix(Y + (1.37 * (V-128)));  // R;

		//		src[x * img->nChannels] = fix(Y + (1.732446 * (U-128))); // B;
		//		src[x * img->nChannels + 1] = fix(Y - (0.698001 * (V-128)) - (0.337633 * (U-128))); // G;
		//		src[x * img->nChannels + 2] = fix(Y + (1.370705 * (V-128)));  // R;
			}
}
  */

// much faster.
// probably it still can faster, but how?
void CCamera :: capture(IplImage* img)
{
   int w = camsize.width;
	int h = camsize.height;

	const int wh = w * h;
	const int wh54 = (int)((wh * 5.0) / 4.0);
   int length = (int)(wh * 1.5 );
 	read(cam_fd, buffer, length);
	
	char* src = img->imageData;

	// Copy the Y component into the B channel of the IplImage
	for(int i=0;i<wh;i++)
	{	
		src[3*i] = buffer[i];
	}

	for(int j=0;j<wh/4;j++)
	{
		unsigned char U = buffer[wh + j];
		unsigned char V = buffer[wh54 + j];
		
		int badd = (int)(1.7 * (U-128));
		int gadd =  (int)(-(0.7 * (V-128)) - (0.34 * (U-128)));
		int radd =   (int)(1.37 * (V-128));

//		int col = 2 * j / w;
//		int row = j%(w/2);
//		int pos = 6 * (col * w + row);		
		int pos = 6 * (( 2 * j / w) * w +  (j%(w/2)));  		

		unsigned char Y = src[pos];
		src[pos] = CONV(Y + badd);
		src[pos+1] = CONV(Y + gadd);
		src[pos+2] = CONV(Y + radd);
	
		pos += 3;

		Y = src[pos];
		src[pos] = CONV(Y + badd);
		src[pos+1] = CONV(Y + gadd);
  		src[pos+2] = CONV(Y + radd);

		pos += 3 *w; 		

		Y = src[pos];
		src[pos] = CONV(Y + badd);
		src[pos+1] = CONV(Y + gadd);
		src[pos+2] = CONV(Y + radd);

		pos -= 3;

		Y = src[pos];
		src[pos] = CONV(Y + badd);
		src[pos+1] = CONV(Y + gadd);
		src[pos+2] = CONV(Y + radd);
	}
}



bool CCamera :: setSize(CvSize sz)
{

	ioctl(cam_fd,VIDIOCGWIN, &vwin);
	vwin.width = sz.width;
	vwin.height = sz.height;
	if(ioctl(cam_fd,VIDIOCSWIN,&vwin) < 0)
	return false;
	else
	{
		free(buffer);
		buffer = (char*)malloc((int)(vwin.width * vwin.height * 1.5));
		camsize = CvSize(sz);
		printf("cam size changed to %i %i \n",camsize.width,camsize.height);
		return true;
	}
}


bool CCamera :: setFrameRate(int newframerate)
{
	ioctl(cam_fd, VIDIOCGWIN, &vwin);
	printf("Camera has framerate setting; current framerate: %d fps\n", (vwin.flags & PWC_FPS_FRMASK) >> PWC_FPS_SHIFT);
	/* Set new framerate */
	vwin.flags &= ~PWC_FPS_FRMASK;
   vwin.flags |= (newframerate << PWC_FPS_SHIFT);
   ioctl(cam_fd, VIDIOCSWIN, &vwin);
	printf(" framerate changed to : %d fps\n", (vwin.flags & PWC_FPS_FRMASK) >> PWC_FPS_SHIFT);
    return true;
}

// not working with my own cams
bool CCamera :: setBlinkMode(int mode)
{
        struct pwc_leds LED;

	    if(mode == 0)
	{        /* Turn LED off */
        LED.led_on = 0;
        LED.led_off = 0;
        ioctl(cam_fd, VIDIOCPWCSLED, &LED);
}
   else if (mode == 1)
 {
        /* Turn LED on solid */
        LED.led_on = 100;
        LED.led_off = 0;
        ioctl(cam_fd, VIDIOCPWCSLED, &LED);
  }
else if(mode == 2)
{
	       LED.led_on = 50;
        LED.led_off = 50;
        ioctl(cam_fd, VIDIOCPWCSLED, &LED);
}
return true;

}