Z301摄像头linux下采集图片程序
Z301摄像头linux下采集图片程序
以下为中星微z301摄像头在linux下的应用程序。现在内核基本包含z301摄像头驱动，下列为应用程序，将USB摄像头插在开发板上，若有打印如
下，说明内核包含此摄像头驱动，并且创建/dev/video2设备。(将下列应用程序的设备修改为/dev/video2)
/dev/videousb 1-1.2: new full speed USB device using s3c2410-ohci and address3
usb 1-1.2: New USB device found, idVendor=0ac8, idProduct=301b
usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 1-1.2: Product: PC Camera
usb 1-1.2: Manufacturer: Vimicro Corp.
gspca: probing 0ac8:301b
zc3xx: probe 2wr ov vga 0x0000
zc3xx: probe sensor -> 0011
zc3xx: Find Sensor HV7131R
input: zc3xx as /devices/platform/s3c2410-ohci/usb1/1-1/1-1.2/input/input1
gspca: video2 created
应用程序：
#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/video2"; //摄像头设备名
static int fd = -1;
struct buffer * buffers = NULL;
static unsigned int n_buffers = 0;
FILE *file_fd; //文件描述字符
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;
/*8.出队列以取得已采集数据的帧缓冲，取得原始采集数据。VIDIOC_DQBUF*/
int ff = ioctl(fd, VIDIOC_DQBUF, &buf);
if (ff < 0)
printf("failture\n"); //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
/*9.将缓冲重新入队列尾,这样可以循环采集。VIDIOC_QBUF*/
ff = ioctl(fd, VIDIOC_QBUF, &buf); //再将其入列
if (ff < 0)//把数据从缓存中读取出来
printf("failture VIDIOC_QBUF\n");
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
/*1.打开设备文件。 int fd=open(”/dev/video0″,O_RDWR);*********/
fd = open(dev_name, O_RDWR /* required */| O_NONBLOCK, 0);//打开设备
/*2.取得设备的capability，看看设备具有什么功能，比如是否具有视频输入,或者音频输入输出等。VIDIOC_QUERYCAP,struct v4l2_capability*/
int ff = ioctl(fd, VIDIOC_QUERYCAP, &cap);//获取摄像头参数
if (ff < 0)
printf("failture VIDIOC_QUERYCAP\n");
/*3.设置视频的制式和帧格式，制式包括PAL，NTSC，帧的格式个包括宽度和高度等。*/
struct v4l2_fmtdesc fmt1;
int ret;
memset(&fmt1, 0, sizeof(fmt1));
fmt1.index = 0;
fmt1.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
//获取当前驱动支持的视频格式
printf("we are here11\n");
while ((ret = ioctl(fd, VIDIOC_ENUM_FMT, &fmt1)) == 0)
{
fmt1.index++;
printf("{ pixelformat = '%c%c%c%c', description = '%s' }\n",
fmt1.pixelformat & 0xFF, (fmt1.pixelformat >> 8) & 0xFF,
(fmt1.pixelformat >> 16) & 0xFF,
(fmt1.pixelformat >> 24) & 0xFF, fmt1.description);
}
//帧的格式，比如宽度，高度等
CLEAR (fmt);
printf("we are here22\n");
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; //数据流类型，必须永远是V4L2_BUF_TYPE_VIDEO_CAPTURE
fmt.fmt.pix.width = 640;//宽，必须是16的倍数
fmt.fmt.pix.height = 480;////高，必须是16的倍数
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_JPEG;//视频数据存储类型//V4L2_PIX_FMT_YUYV;//V4L2_PIX_FMT_YVU420;//V4L2_PIX_FMT_YUYV;
fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
//设置当前驱动的频捕获格式
ff = ioctl(fd, VIDIOC_S_FMT, &fmt);
if (ff < 0)
printf("failture VIDIOC_S_FMT\n");
//计算图片大小
printf("we are here33\n");
file_length = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
/*4.向驱动申请帧缓冲，一般不超过5个。struct v4l2_requestbuffers*/
struct v4l2_requestbuffers req;
CLEAR (req);
req.count = 1;//缓存数量，也就是说在缓存队列里保持多少张照片
req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_MMAP;//或V4L2_MEMORY_USERPTR
ff = ioctl(fd, VIDIOC_REQBUFS, &req); //申请缓冲，count是申请的数量
if (ff < 0)
printf("failture VIDIOC_REQBUFS\n");
if (req.count < 1)
printf("Insufficient buffer memory\n");
buffers = (struct buffer*) calloc(req.count, sizeof(*buffers));//内存中建立对应空间
printf("we are here44\n");
/*5.将申请到的帧缓冲映射到用户空间，这样就可以直接操作采集到的帧了，而不必去复制。mmap*/
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;
//把VIDIOC_REQBUFS中分配的数据缓存转换成物理地址
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 /* start anywhere */, buf.length,
PROT_READ | PROT_WRITE /* required */,
MAP_SHARED /* recommended */, fd, buf.m.offset);//通过mmap建立映射关系,返回映射区的起始地址
if (MAP_FAILED == buffers[n_buffers].start)
printf("mmap failed\n");
}
printf("we are here55\n");
/*6.将申请到的帧缓冲全部入队列，以便存放采集到的数据.VIDIOC_QBUF,struct v4l2_buffer*/
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;
//把数据从缓存中读取出来
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;
/*7.开始视频的采集。VIDIOC_STREAMON*/
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?件描述符集清空
FD_SET(fd, &fds);//在文件描述符集合中增鍔????个新的文件描述符
/* Timeout. */
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->start, buffers->length))
printf("munmap error");
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
/*10.停止视频的采集。VIDIOC_STREAMOFF*/
if (-1 == ioctl(fd, VIDIOC_STREAMOFF, &type))
printf("VIDIOC_STREAMOFF");
/*11.关闭视频设备。close(fd);*/
close(fd);
fclose(file_fd);
exit(EXIT_SUCCESS);
return 0;
}
编译执行：
将上述程序复制到capture.c，编译arm-linux-gcc capture.c –o capture。
将应用程序capture放到开发板上执行即可，即./capture。
转载：http://bbs.chinaunix.net/thread-4083328-1-1.html
