利用摄像头进行图片采集，出不来图片

发布于 2022-10-15 06:25:51 字数 9427 浏览 29 评论 0

用中星微芯片的摄像头zc301p,最后保存为jpg图品，为什么查看图片是空的，但是图片有大小，有48KB。
程序如下：
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <error.h>
#include <assert.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <linux/videodev.h>
#include <unistd.h>

typedef struct v4l
{
int fd;
struct video_capability capability;
struct video_buffer buffer;
struct video_window window;
struct video_channel channel[8];
struct video_picture picture;
struct video_tuner tuner;
struct video_audio audio[8];
struct video_mmap mmap;
struct video_mbuf mbuf;
unsigned char *map;
int frame_current;
int frame_using[VIDEO_MAX_FRAME];
}v4l;

#define ERR_FRAME_BUFFER 1
#define ERR_VIDEO_OPEN 2
#define ERR_VIDEO_GCAP 3
#define ERR_VIDEO_GPIC 4
#define ERR_VIDEO_SPIC 5
#define ERR_SYNC 6
#define ERR_FRAME_USING 7
#define ERR_GET_FRAME 8

#define V4L_FILE "/dev/video0"
#define IMAGINE_SIZE 50000

int open_video(char * fileptr,v4l *vd,int dep,int pal,int width,int height)
{
if ((vd->fd = open(fileptr, O_RDWR)) < 0) {
   perror("v4l_open:");
   return ERR_VIDEO_OPEN;
}
printf("open video success!\n");

//获取设备
if (ioctl(vd->fd, VIDIOCGCAP, &(vd->capability)) < 0) {
   perror("v4l_get_capability:");
   return ERR_VIDEO_GCAP;
}
printf("get device success!");

//获取图象
if (ioctl(vd->fd, VIDIOCGPICT, &(vd->picture)) < 0) {
   perror("v4l_get_picture");
   return ERR_VIDEO_GPIC;
}
printf("get picture success!\n");

//设置图像
vd->picture.palette =pal;
vd->picture.depth = dep;
if (ioctl(vd->fd, VIDIOCSPICT, &(vd->picture)) < 0) {
   perror("v4l_set_palette");
   return ERR_VIDEO_SPIC;
}
vd->mmap.format=pal;
vd->mmap.width=width;
vd->mmap.height=height;
vd->mmap.format=vd->picture.palette;

vd->frame_current = 0;
vd->frame_using[0] = 0;
vd->frame_using[1] = 0;

//获取缓冲映射信息
if (ioctl(vd->fd, VIDIOCGMBUF, &(vd->mbuf)) < 0) {
   perror("v4l_get_mbuf");
   return -1;
}

//建立设备内存映射
vd->map = mmap(0, vd->mbuf.size, PROT_READ|PROT_WRITE, MAP_SHARED, vd->fd, 0);
if(vd->map<0)
{
   perror("v4l_mmap_init:mmap");
   return -1;
}
printf("the video device was opened successfully.\n");
return 0;
}

int get_grab_frame(v4l *vd, int frame)
{
if (vd->frame_using[frame]) {
   fprintf(stderr, "v4l_grab_frame: frame %d is already used.\n", frame);
   return ERR_FRAME_USING;
}
vd->mmap.frame = frame;
if (ioctl(vd->fd, VIDIOCMCAPTURE, &(vd->mmap)) < 0) {
   perror("v4l_grab_frame");
   return ERR_GET_FRAME;
}
vd->frame_using[frame] = 1;
vd->frame_current = frame;
return 0;
}

int get_frist_frame(v4l * vd)
{
int ret;
vd->frame_current=0;
ret=get_grab_frame(vd,vd->frame_current);
if(ret<0)
return ret;
//等待帧同步
   if (ioctl(vd->fd, VIDIOCSYNC, &(vd->frame_current)) < 0) {
   perror("v4l_grab_sync");
   return ERR_SYNC;
}
vd->frame_using[vd->frame_current] = 0;
return 0;
}

unsigned char * get_frame_address(v4l * vd)
{
return (vd->map+vd->mbuf.offsets[vd->frame_current]);
}

int get_next_frame(v4l * vd)
{
int ret;
vd->frame_current^=1;
ret=get_grab_frame(vd,vd->frame_current);
if(ret<0)
return ret;

if(ioctl(vd->fd, VIDIOCSYNC, &(vd->frame_current)) < 0) {
perror("v4l_grab_sync");
return ERR_SYNC;
}
vd->frame_using[vd->frame_current] = 0;
return 0;
}

int save_picture(unsigned char *image,unsigned char *name)
{
FILE *fp;

if(image==NULL)
{
printf("Cannt save picture\n");
return -1;
}

fp=fopen(name,"w");
fwrite(image,IMAGINE_SIZE,1,fp);

fclose(fp);
printf("Capture picture:%s\n",name);
return 0;
}

int main()
{
v4l vd;
int ret,i;
unsigned char *imageptr;
ret=open_video(V4L_FILE,&vd,8,21,320,240);
if(0!=ret)
{
goto err;
}

printf("Name : %s \n",vd.capability.name);
printf("Type: %d \n",vd.capability.type);
printf("Channels: %d \n",vd.capability.channels);
printf("Audios : %d \n",vd.capability.audios);
printf("picture size:%d\n",vd.mbuf.size);

while(1)
{
imageptr=get_frame_address(&vd);
save_picture(imageptr,"haha.jpg");
if(get_next_frame(&vd)!=0)
{
goto err;
}
}
err:
if(vd.fd)
close(vd.fd);
exit(0);
return 0;
}