V4L2摄像头获取单幅图片测试程序
2013-12-19 20:43
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#include
<stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include
<getopt.h>
#include
<fcntl.h>
#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>
#include
<linux/videodev2.h>
#define CLEAR(x) memset
(&(x), 0, sizeof (x))
struct buffer {
void
*
start;
size_t
length;
};
static char
*
dev_name
= "/dev/video0";
static
int
fd
= -1;
struct buffer
*
buffers
= NULL;
FILE *file_fd;
static unsigned long file_length;
static unsigned char *file_name;
int main (int argc,char **
argv)
{
struct v4l2_capability cap;
struct v4l2_format fmt;
file_fd = fopen("test.jpg",
"w");
fd = open (dev_name, O_RDWR | O_NONBLOCK,
0);
ioctl (fd, VIDIOC_QUERYCAP,
&cap);
CLEAR (fmt);
fmt.type
= V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width
= 640;
fmt.fmt.pix.height
= 480;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
fmt.fmt.pix.field
= V4L2_FIELD_INTERLACED;
ioctl (fd, VIDIOC_S_FMT,
&fmt);
file_length =
fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
buffers = calloc (1, sizeof
(*buffers));
buffers[0].length = file_length;
buffers[0].start = malloc (file_length);
for
(;;)
{
fd_set fds;
struct timeval tv;
int r;
FD_ZERO
(&fds);
FD_SET (fd,
&fds);
tv.tv_sec = 3;
tv.tv_usec = 0;
r = select (fd + 1,
&fds, NULL, NULL,
&tv);
if (-1 == r)
{
if (EINTR ==
errno)
continue;
printf
("select");
}
if (0 == r)
{
fprintf
(stderr, "select timeout/n");
exit
(EXIT_FAILURE);
}
if
(read (fd, buffers[0].start, buffers[0].length))
break;
}
fwrite(buffers[0].start,
buffers[0].length, 1, file_fd);
free
(buffers[0].start);
close (fd);
fclose (file_fd);
exit (EXIT_SUCCESS);
return 0;
}
MMAP方式：
#Rockie Cheng
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include
<getopt.h>
#include
<fcntl.h>
#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>
#include
<linux/videodev2.h>
#define CLEAR(x) memset
(&(x), 0, sizeof (x))
struct buffer {
void
*
start;
size_t
length;
};
static char
*
dev_name
= "/dev/video0";//摄像头设备名
static
int
fd
= -1;
struct buffer
*
buffers
= NULL;
static unsigned
int
n_buffers
= 0;
FILE *file_fd;
static unsigned long file_length;
static unsigned char *file_name;
//////////////////////////////////////////////////////
//获取一帧数据
//////////////////////////////////////////////////////
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;
ioctl (fd, VIDIOC_DQBUF,
&buf); //出列采集的帧缓冲
assert (buf.index
< n_buffers);
printf ("buf.index dq is
%d,/n",buf.index);
fwrite(buffers[buf.index].start,
buffers[buf.index].length, 1, file_fd); //将其写入文件中
ioctl (fd, VIDIOC_QBUF,
&buf); //再将其入列
return 1;
}
int main (int argc,char **
argv)
{
struct v4l2_capability cap;
struct v4l2_format fmt;
unsigned int i;
enum v4l2_buf_type type;
file_fd =
fopen("test-mmap.jpg", "w");//图片文件名
fd = open (dev_name, O_RDWR | O_NONBLOCK,
0);//打开设备
ioctl (fd, VIDIOC_QUERYCAP,
&cap);//获取摄像头参数
CLEAR (fmt);
fmt.type
= V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width
= 640;
fmt.fmt.pix.height
= 480;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
fmt.fmt.pix.field
= V4L2_FIELD_INTERLACED;
ioctl (fd, VIDIOC_S_FMT,
&fmt); //设置图像格式
file_length =
fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
//计算图片大小
struct v4l2_requestbuffers
req;
CLEAR (req);
req.count
= 4;
req.type
= V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory
= V4L2_MEMORY_MMAP;
ioctl (fd, VIDIOC_REQBUFS,
&req); //申请缓冲，count是申请的数量
if (req.count
< 2)
printf("Insufficient buffer
memory/n");
buffers = calloc (req.count, sizeof
(*buffers));//内存中建立对应空间
for (n_buffers = 0;
n_buffers < req.count;
++n_buffers)
{
struct v4l2_buffer
buf; //驱动中的一帧
CLEAR (buf);
buf.type
= V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory
= V4L2_MEMORY_MMAP;
buf.index
= n_buffers;
if (-1 == ioctl (fd,
VIDIOC_QUERYBUF, &buf)) //映射用户空间
printf
("VIDIOC_QUERYBUF error/n");
buffers[n_buffers].length = buf.length;
buffers[n_buffers].start
=
mmap (NULL
,
//通过mmap建立映射关系
buf.length,
PROT_READ |
PROT_WRITE ,
MAP_SHARED
,
fd,
buf.m.offset);
if (MAP_FAILED ==
buffers[n_buffers].start)
printf
("mmap failed/n");
}
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 == ioctl (fd, VIDIOC_QBUF,
&buf))//申请到的缓冲进入列队
printf
("VIDIOC_QBUF failed/n");
}
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (-1
== ioctl (fd,
VIDIOC_STREAMON, &type))
//开始捕捉图像数据
printf ("VIDIOC_STREAMON
failed/n");
for (;;)
//这一段涉及到异步IO
{
fd_set fds;
struct timeval tv;
int r;
FD_ZERO
(&fds);//将指定的文件描述符集清空
FD_SET (fd,
&fds);//在文件描述符集合中增加一个新的文件描述符
tv.tv_sec = 2;
tv.tv_usec = 0;
r = select (fd + 1,
&fds, NULL, NULL,
&tv);//判断是否可读（即摄像头是否准备好），tv是定时
if (-1 == r)
{
if (EINTR ==
errno)
continue;
printf
("select err/n");
}
if (0 == r) {
fprintf
(stderr, "select timeout/n");
exit
(EXIT_FAILURE);
}
if (read_frame ())//如果可读，执行read_frame
()函数，并跳出循环
break;
}
unmap:
for (i = 0; i < n_buffers; ++i)
if (-1 == munmap
(buffers[i].start, buffers[i].length))
printf
("munmap error");
close (fd);
fclose (file_fd);
exit (EXIT_SUCCESS);
return 0;
}
<stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include
<getopt.h>
#include
<fcntl.h>
#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>
#include
<linux/videodev2.h>
#define CLEAR(x) memset
(&(x), 0, sizeof (x))
struct buffer {
void
*
start;
size_t
length;
};
static char
*
dev_name
= "/dev/video0";
static
int
fd
= -1;
struct buffer
*
buffers
= NULL;
FILE *file_fd;
static unsigned long file_length;
static unsigned char *file_name;
int main (int argc,char **
argv)
{
struct v4l2_capability cap;
struct v4l2_format fmt;
file_fd = fopen("test.jpg",
"w");
fd = open (dev_name, O_RDWR | O_NONBLOCK,
0);
ioctl (fd, VIDIOC_QUERYCAP,
&cap);
CLEAR (fmt);
fmt.type
= V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width
= 640;
fmt.fmt.pix.height
= 480;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
fmt.fmt.pix.field
= V4L2_FIELD_INTERLACED;
ioctl (fd, VIDIOC_S_FMT,
&fmt);
file_length =
fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
buffers = calloc (1, sizeof
(*buffers));
buffers[0].length = file_length;
buffers[0].start = malloc (file_length);
for
(;;)
{
fd_set fds;
struct timeval tv;
int r;
FD_ZERO
(&fds);
FD_SET (fd,
&fds);
tv.tv_sec = 3;
tv.tv_usec = 0;
r = select (fd + 1,
&fds, NULL, NULL,
&tv);
if (-1 == r)
{
if (EINTR ==
errno)
continue;
printf
("select");
}
if (0 == r)
{
fprintf
(stderr, "select timeout/n");
exit
(EXIT_FAILURE);
}
if
(read (fd, buffers[0].start, buffers[0].length))
break;
}
fwrite(buffers[0].start,
buffers[0].length, 1, file_fd);
free
(buffers[0].start);
close (fd);
fclose (file_fd);
exit (EXIT_SUCCESS);
return 0;
}
MMAP方式：
#Rockie Cheng
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include
<getopt.h>
#include
<fcntl.h>
#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>
#include
<linux/videodev2.h>
#define CLEAR(x) memset
(&(x), 0, sizeof (x))
struct buffer {
void
*
start;
size_t
length;
};
static char
*
dev_name
= "/dev/video0";//摄像头设备名
static
int
fd
= -1;
struct buffer
*
buffers
= NULL;
static unsigned
int
n_buffers
= 0;
FILE *file_fd;
static unsigned long file_length;
static unsigned char *file_name;
//////////////////////////////////////////////////////
//获取一帧数据
//////////////////////////////////////////////////////
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;
ioctl (fd, VIDIOC_DQBUF,
&buf); //出列采集的帧缓冲
assert (buf.index
< n_buffers);
printf ("buf.index dq is
%d,/n",buf.index);
fwrite(buffers[buf.index].start,
buffers[buf.index].length, 1, file_fd); //将其写入文件中
ioctl (fd, VIDIOC_QBUF,
&buf); //再将其入列
return 1;
}
int main (int argc,char **
argv)
{
struct v4l2_capability cap;
struct v4l2_format fmt;
unsigned int i;
enum v4l2_buf_type type;
file_fd =
fopen("test-mmap.jpg", "w");//图片文件名
fd = open (dev_name, O_RDWR | O_NONBLOCK,
0);//打开设备
ioctl (fd, VIDIOC_QUERYCAP,
&cap);//获取摄像头参数
CLEAR (fmt);
fmt.type
= V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width
= 640;
fmt.fmt.pix.height
= 480;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
fmt.fmt.pix.field
= V4L2_FIELD_INTERLACED;
ioctl (fd, VIDIOC_S_FMT,
&fmt); //设置图像格式
file_length =
fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
//计算图片大小
struct v4l2_requestbuffers
req;
CLEAR (req);
req.count
= 4;
req.type
= V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory
= V4L2_MEMORY_MMAP;
ioctl (fd, VIDIOC_REQBUFS,
&req); //申请缓冲，count是申请的数量
if (req.count
< 2)
printf("Insufficient buffer
memory/n");
buffers = calloc (req.count, sizeof
(*buffers));//内存中建立对应空间
for (n_buffers = 0;
n_buffers < req.count;
++n_buffers)
{
struct v4l2_buffer
buf; //驱动中的一帧
CLEAR (buf);
buf.type
= V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory
= V4L2_MEMORY_MMAP;
buf.index
= n_buffers;
if (-1 == ioctl (fd,
VIDIOC_QUERYBUF, &buf)) //映射用户空间
printf
("VIDIOC_QUERYBUF error/n");
buffers[n_buffers].length = buf.length;
buffers[n_buffers].start
=
mmap (NULL
,
//通过mmap建立映射关系
buf.length,
PROT_READ |
PROT_WRITE ,
MAP_SHARED
,
fd,
buf.m.offset);
if (MAP_FAILED ==
buffers[n_buffers].start)
printf
("mmap failed/n");
}
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 == ioctl (fd, VIDIOC_QBUF,
&buf))//申请到的缓冲进入列队
printf
("VIDIOC_QBUF failed/n");
}
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (-1
== ioctl (fd,
VIDIOC_STREAMON, &type))
//开始捕捉图像数据
printf ("VIDIOC_STREAMON
failed/n");
for (;;)
//这一段涉及到异步IO
{
fd_set fds;
struct timeval tv;
int r;
FD_ZERO
(&fds);//将指定的文件描述符集清空
FD_SET (fd,
&fds);//在文件描述符集合中增加一个新的文件描述符
tv.tv_sec = 2;
tv.tv_usec = 0;
r = select (fd + 1,
&fds, NULL, NULL,
&tv);//判断是否可读（即摄像头是否准备好），tv是定时
if (-1 == r)
{
if (EINTR ==
errno)
continue;
printf
("select err/n");
}
if (0 == r) {
fprintf
(stderr, "select timeout/n");
exit
(EXIT_FAILURE);
}
if (read_frame ())//如果可读，执行read_frame
()函数，并跳出循环
break;
}
unmap:
for (i = 0; i < n_buffers; ++i)
if (-1 == munmap
(buffers[i].start, buffers[i].length))
printf
("munmap error");
close (fd);
fclose (file_fd);
exit (EXIT_SUCCESS);
return 0;
}
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