10-1. V4L2를 사용한 bitmap 촬영 C소스

출처 : https://ameblo.jp/sy-eng/entry-12072692011.html

saibara 씨의 소스 코드를 분할시켰다.

capture.h

	#ifndef __CAPTURE_H__
	#define __CAPTURE_H__
	#define OUTFILE_NAME "capture.bmp"
	#define COUNT_IGNORE 10 // frame count for initilize camera
	#define IMAGE_WIDTH 640
	#define IMAGE_HEIGHT 480
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <stdint.h>
	#include <assert.h>
	#include <fcntl.h> /* low-level i/o */
	#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> /* for videodev2.h */
	#include <linux/videodev2.h>
	#define CLEAR(x) memset (&(x), 0, sizeof (x))
	#define uchar unsigned char
	/* sequence
	*open_device();
	*init_device();
	*start_capturing();
	*mainloop();
	*stop_capturing();
	*uninit_device();
	*close_device();
	*exit(EXIT_SUCCESS);
	*/
	static void open_device(void);
	static void init_device(void);
	static void start_capturing(void);
	static void mainloop(void);
	static void stop_capturing (void);
	static void uninit_device(void);
	static void close_device(void);
	void captureBM(void);
	#endif //capture.h

capture.c

#include "capture.h"

struct buffer {

void * start;

size_t length;

};

static char * dev_name = "/dev/video0";

static int fd = -1;

struct buffer * buffers = NULL;

static unsigned int n_buffers = 0;

static void errno_exit(const char *s)

{

fprintf(stderr, "%s error %d, %s\n",s, errno, strerror(errno));

exit(EXIT_FAILURE);

}

static int xioctl(int fd,int request,void *arg)

{

int r;

do{ r = ioctl(fd, request, arg); }

while(-1 == r && EINTR == errno);

return r;

}

void saveBitmapFile(char* fileName, uchar* R, uchar* G, uchar* B, int width, int height){

FILE* fp;

int i;

fp = fopen(OUTFILE_NAME,"wb");

if(fp == NULL) return;

//file header

fprintf(fp, "BM");

//If (IMAGE_WIDTH * 3) is not the multiple of 4, some 0(s) must be added to make it multiple of 4.

uint32_t fileSize = 14 + 40 + (IMAGE_WIDTH*3)*IMAGE_HEIGHT;

fwrite(&fileSize, 4, 1, fp);

uint32_t reserved = 0;

fwrite(&reserved, 4, 1, fp);

uint32_t offset = 54;

fwrite(&offset, 4, 1, fp);

//information header

uint32_t size = 40;

fwrite(&size, 4, 1, fp);

int32_t tWidth =(int32_t)width;

fwrite(&tWidth, 4, 1, fp);

int32_t tHeight = (int32_t)height;

fwrite(&tHeight, 4, 1, fp);

uint16_t plane = 1;

fwrite(&plane, 2, 1, fp);

uint16_t bit = 24;

fwrite(&bit, 2, 1, fp);

uint32_t compression = 0;

fwrite(&compression, 4, 1, fp);

//No additional 0(s);

size = (IMAGE_WIDTH*3)*IMAGE_HEIGHT;

fwrite(&size, 4, 1, fp);

uint32_t zero = 0;

fwrite(&zero, 4, 1, fp);

fwrite(&zero, 4, 1, fp);

fwrite(&zero, 4, 1, fp);

fwrite(&zero, 4, 1, fp);

//image data

//no additional 0(s)

for(i = 0; i < IMAGE_WIDTH*IMAGE_HEIGHT; i++){

fwrite(B+i, 1, 1, fp);

fwrite(G+i, 1, 1, fp);

fwrite(R+i, 1, 1, fp);

}

fclose(fp);

printf("Saved\n");

return;

}

static void process_image(const void *p_buf,const int len_buf)

{

int i, width, height;

uchar *d1,*d2,buf;

uchar Y[IMAGE_WIDTH * IMAGE_HEIGHT];

uchar Cb[IMAGE_WIDTH * IMAGE_HEIGHT];

uchar Cr[IMAGE_WIDTH * IMAGE_HEIGHT];

uchar R[IMAGE_WIDTH * IMAGE_HEIGHT];

uchar G[IMAGE_WIDTH * IMAGE_HEIGHT];

uchar B[IMAGE_WIDTH * IMAGE_HEIGHT];

printf("Capture size : %d\n",len_buf);

// mmm... swap byte order

/*

for(i=0;i<len_buf;i+=2)

{

d1 = (char *)(p_buf) + i;

d2 = (char *)(p_buf) + i + 1;

buf = *d1;

*d1 = *d2;

*d2 = buf;

}

*/

//The format must be Y0CbY1Cr

d1 = (uchar *)(p_buf);

int index = 0;

for(height = 0; height < IMAGE_HEIGHT; height++){

for(width = 0; width < IMAGE_WIDTH; width += 2){

Y[index] = *d1;

d1++;

Cb[index] = *d1;

index++;

Cb[index] = *d1;

d1++;

Y[index] = *d1;

d1++;

Cr[index-1] = *d1;

Cr[index] = *d1;

d1++;

index++;

}

}

int imageSize = IMAGE_WIDTH*IMAGE_HEIGHT;

for(index = 0; index < imageSize; index++){

double U = Cb[index] - 128;

double V = Cr[index] - 128;

R[index] = (uchar)(Y[index] + 1.402*V);

G[index] = (uchar)(Y[index] - 0.344*U -0.714*V);

B[index] = (uchar)(Y[index] + 1.772*U);

//printf("%d %d %d\n", R[index], G[index], B[index]);

}

saveBitmapFile(OUTFILE_NAME, R, G, B, IMAGE_WIDTH, IMAGE_HEIGHT);

}

static int read_frame(int count)

{

struct v4l2_buffer buf;

CLEAR(buf);

buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

buf.memory = V4L2_MEMORY_MMAP;

if(-1 == xioctl(fd, VIDIOC_DQBUF, &buf))

{

switch(errno)

{

case EAGAIN:

return 0;

case EIO:

/* Could ignore EIO, see spec. */

/* fall through */

default:

errno_exit("VIDIOC_DQBUF");

}

}

assert(buf.index < n_buffers);

if(count == 0)

process_image(buffers[buf.index].start,buffers[buf.index].length);

if(-1 == xioctl(fd, VIDIOC_QBUF, &buf))

errno_exit("VIDIOC_QBUF");

return 1;

}

static void mainloop(void)

{

unsigned int count;

count = COUNT_IGNORE;

while(count-- > 0)

{

for(;;)

{

fd_set fds;

struct timeval tv;

int r;

FD_ZERO(&fds);

FD_SET(fd, &fds);

/* Timeout. */

tv.tv_sec = 2;

tv.tv_usec = 0;

r = select(fd + 1, &fds, NULL, NULL, &tv);

if(-1 == r)

{

if(EINTR == errno)

continue;

errno_exit("select");

}

if(0 == r)

{

fprintf(stderr, "select timeout\n");

exit(EXIT_FAILURE);

}

if(read_frame(count))

break;

/* EAGAIN - continue select loop. */

}

}

}

static void stop_capturing (void)

{

enum v4l2_buf_type type;

type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

if(-1 == xioctl(fd, VIDIOC_STREAMOFF, &type))

errno_exit("VIDIOC_STREAMOFF");

}

static void start_capturing(void)

{

unsigned int i;

enum v4l2_buf_type type;

for(i = 0; i < n_buffers; ++i)

{

struct v4l2_buffer buf;

CLEAR(buf);

buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

buf.memory = V4L2_MEMORY_MMAP;

buf.index = i;

if(-1 == xioctl(fd, VIDIOC_QBUF, &buf))

errno_exit("VIDIOC_QBUF");

}

type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

if(-1 == xioctl(fd, VIDIOC_STREAMON, &type))

errno_exit("VIDIOC_STREAMON");

}

static void uninit_device(void)

{

unsigned int i;

for(i = 0; i < n_buffers; ++i)

if(-1 == munmap(buffers[i].start, buffers[i].length))

errno_exit("munmap");

free(buffers);

}

static void init_mmap(void)

{

struct v4l2_requestbuffers req;

CLEAR(req);

req.count = 8;

req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

req.memory = V4L2_MEMORY_MMAP;

if(-1 == xioctl(fd, VIDIOC_REQBUFS, &req))

{

if(EINVAL == errno)

{

fprintf(stderr, "%s does not support "

"memory mapping\n", dev_name);

exit(EXIT_FAILURE);

}

else

{

errno_exit("VIDIOC_REQBUFS");

}

}

if(req.count < 2)

{

fprintf(stderr, "Insufficient buffer memory on %s\n",

dev_name);

exit(EXIT_FAILURE);

}

buffers = calloc(req.count, sizeof(*buffers));

if(!buffers)

{

fprintf(stderr, "Out of memory\n");

exit(EXIT_FAILURE);

}

for(n_buffers = 0; n_buffers < req.count; ++n_buffers)

{

struct v4l2_buffer buf;

CLEAR(buf);

buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

buf.memory = V4L2_MEMORY_MMAP;

buf.index = n_buffers;

if(-1 == xioctl(fd, VIDIOC_QUERYBUF, &buf))

errno_exit("VIDIOC_QUERYBUF");

// printf("Buffer length : %d : %d\n",n_buffers,buf.length);

buffers[n_buffers].length = buf.length;

buffers[n_buffers].start =

mmap(NULL /* start anywhere */,

buf.length,

PROT_READ | PROT_WRITE /* required */,

MAP_SHARED /* recommended */,

fd, buf.m.offset);

if(MAP_FAILED == buffers[n_buffers].start)

errno_exit("mmap");

}

}

static void init_device(void)

{

struct v4l2_capability cap;

struct v4l2_cropcap cropcap;

struct v4l2_crop crop;

struct v4l2_format fmt;

unsigned int min;

if(-1 == xioctl(fd, VIDIOC_QUERYCAP, &cap))

{

if(EINVAL == errno)

{

fprintf(stderr, "%s is no V4L2 device\n",dev_name);

exit(EXIT_FAILURE);

}

else

{

errno_exit("VIDIOC_QUERYCAP");

}

}

if(!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE))

{

fprintf(stderr, "%s is no video capture device\n",dev_name);

exit(EXIT_FAILURE);

}

if(!(cap.capabilities & V4L2_CAP_STREAMING))

{

fprintf(stderr, "%s does not support streaming i/o\n",

dev_name);

exit(EXIT_FAILURE);

}

/* Select video input, video standard and tune here. */

CLEAR(cropcap);

cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

if(0 == xioctl(fd, VIDIOC_CROPCAP, &cropcap))

{

crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

crop.c = cropcap.defrect; /* reset to default */

if(-1 == xioctl(fd, VIDIOC_S_CROP, &crop))

{

switch(errno)

{

case EINVAL:

/* Cropping not supported. */

break;

default:

/* Errors ignored. */

break;

}

}

}

else

{

/* Errors ignored. */

}

CLEAR(fmt);

fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

fmt.fmt.pix.width = IMAGE_WIDTH;

fmt.fmt.pix.height = IMAGE_HEIGHT;

fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;

//fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;

fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;

if(-1 == xioctl(fd, VIDIOC_S_FMT, &fmt)) errno_exit("VIDIOC_S_FMT");

/* Note VIDIOC_S_FMT may change width and height. */

/* Buggy driver paranoia. */

min = fmt.fmt.pix.width * 2;

//min = fmt.fmt.pix.width * 3;

if(fmt.fmt.pix.bytesperline < min) fmt.fmt.pix.bytesperline = min;

min = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;

if(fmt.fmt.pix.sizeimage < min) fmt.fmt.pix.sizeimage = min;

printf("%d\n", fmt.fmt.pix.sizeimage);

init_mmap();

}

static void close_device(void)

{

if(-1 == close(fd)) errno_exit("close");

fd = -1;

}

static void open_device(void)

{

struct stat st;

if(-1 == stat(dev_name, &st))

{

fprintf(stderr, "Cannot identify '%s': %d, %s\n",

dev_name, errno, strerror(errno));

exit(EXIT_FAILURE);

}

if(!S_ISCHR(st.st_mode))

{

fprintf(stderr, "%s is no device\n", dev_name);

exit(EXIT_FAILURE);

}

fd = open(dev_name, O_RDWR /* required */ | O_NONBLOCK, 0);

if(-1 == fd)

{

fprintf(stderr, "Cannot open '%s': %d, %s\n",

dev_name, errno, strerror(errno));

exit(EXIT_FAILURE);

}

}

/*

int main (int argc,char **argv)

{

dev_name = "/dev/video0";

open_device();

init_device();

start_capturing();

mainloop();

stop_capturing();

uninit_device();

close_device();

exit(EXIT_SUCCESS);

return 0;

}

*/

void captureBM(void)

{

open_device();

init_device();

start_capturing();

mainloop();

stop_capturing();

uninit_device();

close_device();

}