| lkppost |
2008-10-15 16:58 |
Re:linux 下v4l2视频采集的问题
如题，流程基本调通，就是从内存读取数据保存的时候不知道该如何操作，请各位帮忙看一下。多谢。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>
#include <assert.h>
#include <getopt.h> // getopt_long()
#include <fcntl.h>
#include <unistd.h> // low-level i/o
#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>
#include <jpeglib.h>
using namespace std;
#define CLEAR(x) memset (&(x), 0, sizeof (x))
typedef enum {
IO_METHOD_READ,
IO_METHOD_MMAP,
IO_METHOD_USERPTR,
} io_method;
struct buffer {
void * start;
size_t length;
};
const char * dev_name= "/dev/video0";
static io_method io = IO_METHOD_MMAP;
const int pixel_format= V4L2_PIX_FMT_YUV420;
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;
}
int save_jpeg(char *buf, int size) //淇濆瓨閲囬泦鍒扮殑鍥惧儚鍒版枃浠朵腑
{
FILE *fp, *fp1;
static int inc=0;
fp=fopen(DEVICE,"w+")
char bewf[128];
sprintf(bewf, "image-%d.jpeg", inc);
if ((fp1=fopen(bewf, "w+"))==NULL) {
perror("open");
exit(1);
}
if(fwrite(buf, size, 1, fp)==NULL)
{
perror("write");
exit(1);
}
inc++;
fclose(fp1);
fclose(fp);
}
static void process_image(char * p, ssize_t size) {
save_jpeg((char *)p,size);
/*char * buf;
buf = (char *)p;
for(int i = 0;i<100;i++)
{
printf("%x \n",*buf++);
}*/
/*static int no_image = 0;
char filename[1024];
int fd;
ssize_t written = 0;
snprintf(fiename, sizeof(filename), "/tmp/webcam-%5.5d.%s", no_image++,
pixel_format == V4L2_PIX_FMT_YUV420 ? "yuv" : "raw");
fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, S_IRUSR | S_IWUSR);
if (fd < 0) {
fputc('*', stdout);
fflush(stdout);
return;
}
do {
int ret;
ret = write(fd, (char *)p + written, size - written);
if (ret < 0) {
fputc('+', stdout);
fflush(stdout);
return;
}
written += ret;
} while (written < size);
close(fd);*/
/*char picbuf[size];
unsigned char outbuf[size];
unsigned char i_tmp;
static int i_loop = 0;
char s_namebuf[128];
FILE *f_out;
sprintf(s_namebuf, "./vidout/out_%d.ppm", i_loop++);
cout<<s_namebuf<<endl;
f_out = fopen(s_namebuf, "w+");
memcpy(picbuf, p, size);
for (int i_swap=0; i_swap<size; i_swap+=3) {
outbuf[i_swap+0] = picbuf[i_swap+2];
outbuf[i_swap+1] = picbuf[i_swap+1];
outbuf[i_swap+2] = picbuf[i_swap+0];
}
fwrite(outbuf, size, 1,f_out);
fclose(f_out);
cout<<"******************"<<endl;*/
fputc('.', stdout);
fflush(stdout);
}
static int read_frame(void) {
struct v4l2_buffer buf;
unsigned int i;
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);
process_image((char *)buffers[buf.index].start, buf.length);
if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
errno_exit("VIDIOC_QBUF");
return 1;
}
static void mainloop(void) {
unsigned int count;
count = 10;
while (count-- > 0) {
for (;;) {
fd_set fds;
/*struct timeval tv;
int r;
FD_ZERO (&fds);
FD_SET (fd, &fds);
tv.tv_sec = 2;// Timeout.
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())
break;
}
}
}
static void stop_capturing(void) {
cout<<endl<<"stop_capturing"<<endl;
}
static void start_capturing(void) {
cout<<"start_capturing"<<endl;
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.start, buffers.length))
errno_exit("munmap");
free(buffers);
}
static void init_read(unsigned int buffer_size) {
buffers = (buffer *)calloc(1, sizeof (*buffers));
if (!buffers) {
fprintf(stderr, "Out of memory\n");
exit(EXIT_FAILURE);
}
buffers[0].length = buffer_size;
buffers[0].start = malloc(buffer_size);
if (!buffers[0].start) {
fprintf(stderr, "Out of memory\n");
exit(EXIT_FAILURE);
}
}
static void init_mmap(void) {
struct v4l2_requestbuffers req;
CLEAR (req);
req.count = 4;
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");
}
}
cout<<"VIDIOC_REQBUFS success!"<<endl;
if (req.count < 2) {
fprintf(stderr, "Insufficient buffer memory on %s\n",
dev_name);
exit(EXIT_FAILURE);
}
buffers = (buffer *)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");
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)
errno_exit("mmap");
}
}
static void init_userp(unsigned int buffer_size) {
struct v4l2_requestbuffers req;
unsigned int page_size;
page_size = getpagesize();
buffer_size = (buffer_size + page_size - 1) & ~(page_size - 1);
CLEAR (req);
req.count = 4;
req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_USERPTR;
if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req)) {
if (EINVAL == errno) {
fprintf(stderr, "%s does not support "
"user pointer i/o\n", dev_name);
exit(EXIT_FAILURE);
} else {
errno_exit("VIDIOC_REQBUFS");
}
}
cout<<"VIDIOC_REQBUFS success!"<<endl;
buffers = (buffer *)calloc(4, sizeof (*buffers));
if (!buffers) {
fprintf(stderr, "Out of memory\n");
exit(EXIT_FAILURE);
}
for (n_buffers = 0; n_buffers < 4; ++n_buffers) {
buffers[n_buffers].length = buffer_size;
buffers[n_buffers].start = memalign(page_size, buffer_size);
if (!buffers[n_buffers].start) {
fprintf(stderr, "Out of memory\n");
exit(EXIT_FAILURE);
}
}
}
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");
}
}
cout<<"VIDIOC_QUERYCAP success!"<<endl;
if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
fprintf(stderr, "%s is no video capture device\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 = 320;
fmt.fmt.pix.height = 240;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
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;
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;
init_mmap();
}
static void close_device(void) {
if (-1 == close(fd))
errno_exit("close");
fd = -1;
}
static void open_device(void) {
struct stat st;
cout<<"dev_name"<<dev_name<<endl;
if (-1 == stat(dev_name, &st)) {
fprintf(stderr, "Cannot identify 鈥?s鈥? %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 | O_NONBLOCK, 0);
if (-1 == fd) {
fprintf(stderr, "Cannot open 鈥?s鈥? %d, %s\n",
dev_name, errno, strerror (errno));
exit(EXIT_FAILURE);
}
cout<<"open success!"<<endl;
}
int main(int argc, char ** argv) {
io = IO_METHOD_MMAP;
open_device();
init_device();
start_capturing();
mainloop();
stop_capturing();
uninit_device();
close_device();
exit(EXIT_SUCCESS);
return 0;
} |
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