USB摄像头使用记录
文章目录
1.概述
1.1 v4l2介绍
2.使用
2.1linux应用
2.1.1获取并打印摄像头参数
自己编写思路：
utils的结构体定义：明天处理下
/*
* @Descripttion:
* @version:
* @Author: Andy
* @Date: 2024-06-06 00:18:52
* @LastEditors: Andy
* @LastEditTime: 2024-06-06 00:24:12
*/
#ifndef __CAMERA_UTILS_H__
#define __CAMERA_UTILS_H__
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <linux/types.h> /* for videodev2.h */
#include <linux/videodev2.h>
typedef struct my_camera_ctrl
{
int fd; //file_handle
struct v4l2_fmtdesc fmtdesc;
} camera_ctrl_t;
#endif
#include"main.h"
/*
* @Descripttion:
* @version:
* @Author: Andy
* @Date: 2024-06-03 23:21:25
* @LastEditors: Andy
* @LastEditTime: 2024-06-06 00:30:37
*/
int main(int argc, char const *argv[])
{
//打开文件
//调用自定义的打印摄像头接口
//其他操作
目前先将摄像头的应用层功能遍历操作一遍后再深究驱动,接着移植qt,实现界面驱动硬件的项目模块化集成过程
return 0;
}
2.2linux驱动
3.调试
3.1应用调试
常用的VIDIOC命令：
1. VIDIOC_QUERYCAP （查询设备属性）
2. VIDIOC_ENUM_FMT (显示所有支持的格式)
3. VIDIOC_S_FMT （设置视频捕获格式）
4. VIDIOC_G_FMT （获取硬件现在的视频捕获格式）
5. VIDIOC_TRY_FMT （检查是否支持某种帧格式）
6. VIDIOC_ENUM_FRAMESIZES （枚举设备支持的分辨率信息）
7. VIDIOC_ENUM_FRAMEINTERVALS (获取设备支持的帧间隔)
8. VIDIOC_S_PARM && VIDIOC_G_PARM (设置和获取流参数)
9. VIDIOC_QUERYCAP (查询驱动的修剪能力)
10. VIDIOC_S_CROP (设置视频信号的边框)
11. VIDIOC_G_CROP (读取设备信号的边框)
12. VIDIOC_REQBUFS (向设备申请缓存区)
13. VIDIOC_QUERYBUF (获取缓存帧的地址、长度)
14. VIDIOC_QBUF (把帧放入队列)
15. VIDIOC_DQBUF (从队列中取出帧)
16. VIDIOC_STREAMON && VIDIOC_STREAMOFF (启动/停止视频数据流)
原文链接：https://blog.youkuaiyun.com/mark_minge/article/details/81427489
3.1.1 获取并打印摄像头参数
头文件：
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <linux/types.h>
#include <linux/videodev2.h> /* for videodev2.h */
关键结构体：
struct v4l2_fmtdesc
{
u32 index; // 要查询的格式序号，应用程序设置
enum v4l2_buf_type type; // 帧类型，应用程序设置
u32 flags; // 是否为压缩格式
u8 description[32]; // 格式名称
u32 pixelformat; // 格式
u32 reserved[4]; // 保留
};
struct v4l2_frmsizeenum {
__u32 index; /* Frame size number */
__u32 pixel_format; /* 像素格式 */
__u32 type; /* type */
union { /* Frame size */
struct v4l2_frmsize_discrete discrete;
struct v4l2_frmsize_stepwise stepwise;
};
__u32 reserved[2]; /* Reserved space for future use */
};
struct v4l2_frmsize_discrete {
__u32 width; /* Frame width [pixel] */
__u32 height; /* Frame height [pixel] */
};
.c
/*
* @Descripttion:
* @version:
* @Author: Andy
* @Date: 2024-05-26 00:03:08
* @LastEditors: Andy
* @LastEditTime: 2024-05-26 00:06:05
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <linux/types.h> /* for videodev2.h */
#include <linux/videodev2.h>
/* ./video_test </dev/video0> */
int main(int argc, char **argv)
{
int fd;
struct v4l2_fmtdesc fmtdesc;
struct v4l2_frmsizeenum fsenum;
int fmt_index = 0;
int frame_index = 0;
if (argc != 2)
{
printf("Usage: %s </dev/videoX>, print format detail for video device\n", argv[0]);
return -1;
}
/* open */
fd = open(argv[1], O_RDWR);
if (fd < 0)
{
printf("can not open %s\n", argv[1]);
return -1;
}
while (1)
{
/* 枚举格式 */
fmtdesc.index = fmt_index; // 比如从0开始
fmtdesc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; // 指定type为"捕获"
if (0 != ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc))
break;
frame_index = 0;
while (1)
{
/* 枚举这种格式所支持的帧大小 */
memset(&fsenum, 0, sizeof(struct v4l2_frmsizeenum));
fsenum.pixel_format = fmtdesc.pixelformat;
fsenum.index = frame_index;
if (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &fsenum) == 0)
{
printf("format %s,%d, framesize %d: %d x %d\n", fmtdesc.description, fmtdesc.pixelformat, frame_index, fsenum.discrete.width, fsenum.discrete.height);
}
else
{
break;
}
frame_index++;
}
fmt_index++;
}
return 0;
}
3.1.2get_data.c
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <linux/types.h> /* for videodev2.h */
#include <linux/videodev2.h>
#include <poll.h>
#include <sys/mman.h>
/* ./video_test </dev/video0> */
int main(int argc, char **argv)
{
int fd;
struct v4l2_fmtdesc fmtdesc;
struct v4l2_frmsizeenum fsenum;
int fmt_index = 0;
int frame_index = 0;
int i;
void *bufs[32];
int buf_cnt;
int type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
struct pollfd fds[1];
char filename[32];
int file_cnt = 0;
if (argc != 2)
{
printf("Usage: %s </dev/videoX>, print format detail for video device\n", argv[0]);
return -1;
}
/* open */
fd = open(argv[1], O_RDWR);
if (fd < 0)
{
printf("can not open %s\n", argv[1]);
return -1;
}
/* 查询能力 */
struct v4l2_capability cap;
memset(&cap, 0, sizeof(struct v4l2_capability));
if (0 == ioctl(fd, VIDIOC_QUERYCAP, &cap))
{
if((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == 0) {
fprintf(stderr, "Error opening device %s: video capture not supported.\n",
argv[1]);
return -1;
}
if(!(cap.capabilities & V4L2_CAP_STREAMING)) {
fprintf(stderr, "%s does not support streaming i/o\n", argv[1]);
return -1;
}
}
else
{
printf("can not get capability\n");
return -1;
}
while (1)
{
/* 枚举格式 */
fmtdesc.index = fmt_index; // 比如从0开始
fmtdesc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; // 指定type为"捕获"
if (0 != ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc))
break;
frame_index = 0;
while (1)
{
/* 枚举这种格式所支持的帧大小 */
memset(&fsenum, 0, sizeof(struct v4l2_frmsizeenum));
fsenum.pixel_format = fmtdesc.pixelformat;
fsenum.index = frame_index;
if (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &fsenum) == 0)
{
printf("format %s,%d, framesize %d: %d x %d\n", fmtdesc.description, fmtdesc.pixelformat, frame_index, fsenum.discrete.width, fsenum.discrete.height);
}
else
{
break;
}
frame_index++;
}
fmt_index++;
}
/* 设置格式 */
struct v4l2_format fmt;
memset(&fmt, 0, sizeof(struct v4l2_format));
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width = 1024;
fmt.fmt.pix.height = 768;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
fmt.fmt.pix.field = V4L2_FIELD_ANY;
if (0 == ioctl(fd, VIDIOC_S_FMT, &fmt))
{
printf("set format ok: %d x %d\n", fmt.fmt.pix.width, fmt.fmt.pix.height);
}
else
{
printf("can not set format\n");
return -1;
}
/*
* 申请buffer
*/
struct v4l2_requestbuffers rb;
memset(&rb, 0, sizeof(struct v4l2_requestbuffers));
rb.count = 32;
rb.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
rb.memory = V4L2_MEMORY_MMAP;
if (0 == ioctl(fd, VIDIOC_REQBUFS, &rb))
{
/* 申请成功后, mmap这些buffer */
buf_cnt = rb.count;
for(i = 0; i < rb.count; i++) {
struct v4l2_buffer buf;
memset(&buf, 0, sizeof(struct v4l2_buffer));
buf.index = i;
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (0 == ioctl(fd, VIDIOC_QUERYBUF, &buf))
{
/* mmap */
bufs[i] = mmap(0 /* start anywhere */ ,
buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
buf.m.offset);
if(bufs[i] == MAP_FAILED) {
perror("Unable to map buffer");
return -1;
}
}
else
{
printf("can not query buffer\n");
return -1;
}
}
printf("map %d buffers ok\n", buf_cnt);
}
else
{
printf("can not request buffers\n");
return -1;
}
/* 把所有buffer放入"空闲链表" */
for(i = 0; i < buf_cnt; ++i) {
struct v4l2_buffer buf;
memset(&buf, 0, sizeof(struct v4l2_buffer));
buf.index = i;
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
{
perror("Unable to queue buffer");
return -1;
}
}
printf("queue buffers ok\n");
/* 启动摄像头 */
if (0 != ioctl(fd, VIDIOC_STREAMON, &type))
{
perror("Unable to start capture");
return -1;
}
printf("start capture ok\n");
while (1)
{
/* poll */
memset(fds, 0, sizeof(fds));
fds[0].fd = fd;
fds[0].events = POLLIN;
if (1 == poll(fds, 1, -1))
{
/* 把buffer取出队列 */
struct v4l2_buffer buf;
memset(&buf, 0, sizeof(struct v4l2_buffer));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (0 != ioctl(fd, VIDIOC_DQBUF, &buf))
{
perror("Unable to dequeue buffer");
return -1;
}
/* 把buffer的数据存为文件 */
sprintf(filename, "video_raw_data_%04d.jpg", file_cnt++);
int fd_file = open(filename, O_RDWR | O_CREAT, 0666);
if (fd_file < 0)
{
printf("can not create file : %s\n", filename);
}
printf("capture to %s\n", filename);
write(fd_file, bufs[buf.index], buf.bytesused);
close(fd_file);
/* 把buffer放入队列 */
if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
{
perror("Unable to queue buffer");
return -1;
}
}
}
if (0 != ioctl(fd, VIDIOC_STREAMOFF, &type))
{
perror("Unable to stop capture");
return -1;
}
printf("stop capture ok\n");
close(fd);
return 0;
}
3.1.3 ctrl_light
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <linux/types.h> /* for videodev2.h */
#include <linux/videodev2.h>
#include <poll.h>
#include <sys/mman.h>
#include <pthread.h>
/* ./video_test </dev/video0> */
static void *thread_brightness_control (void *args)
{
int fd = (int)args;
unsigned char c;
int brightness;
int delta;
struct v4l2_queryctrl qctrl;
memset(&qctrl, 0, sizeof(qctrl));
qctrl.id = V4L2_CID_BRIGHTNESS; // V4L2_CID_BASE+0;
if (0 != ioctl(fd, VIDIOC_QUERYCTRL, &qctrl))
{
printf("can not query brightness\n");
return NULL;
}
printf("brightness min = %d, max = %d\n", qctrl.minimum, qctrl.maximum);
delta = (qctrl.maximum - qctrl.minimum) / 10;
struct v4l2_control ctl;
ctl.id = V4L2_CID_BRIGHTNESS; // V4L2_CID_BASE+0;
ioctl(fd, VIDIOC_G_CTRL, &ctl);
while (1)
{
c = getchar();
if (c == 'u' || c == 'U')
{
ctl.value += delta;
}
else if (c == 'd' || c == 'D')
{
ctl.value -= delta;
}
if (ctl.value > qctrl.maximum)
ctl.value = qctrl.maximum;
if (ctl.value < qctrl.minimum)
ctl.value = qctrl.minimum;
ioctl(fd, VIDIOC_S_CTRL, &ctl);
}
return NULL;
}
int main(int argc, char **argv)
{
int fd;
struct v4l2_fmtdesc fmtdesc;
struct v4l2_frmsizeenum fsenum;
int fmt_index = 0;
int frame_index = 0;
int i;
void *bufs[32];
int buf_cnt;
int type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
struct pollfd fds[1];
char filename[32];
int file_cnt = 0;
if (argc != 2)
{
printf("Usage: %s </dev/videoX>, print format detail for video device\n", argv[0]);
return -1;
}
/* open */
fd = open(argv[1], O_RDWR);
if (fd < 0)
{
printf("can not open %s\n", argv[1]);
return -1;
}
/* 查询能力 */
struct v4l2_capability cap;
memset(&cap, 0, sizeof(struct v4l2_capability));
if (0 == ioctl(fd, VIDIOC_QUERYCAP, &cap))
{
if((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == 0) {
fprintf(stderr, "Error opening device %s: video capture not supported.\n",
argv[1]);
return -1;
}
if(!(cap.capabilities & V4L2_CAP_STREAMING)) {
fprintf(stderr, "%s does not support streaming i/o\n", argv[1]);
return -1;
}
}
else
{
printf("can not get capability\n");
return -1;
}
while (1)
{
/* 枚举格式 */
fmtdesc.index = fmt_index; // 比如从0开始
fmtdesc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; // 指定type为"捕获"
if (0 != ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc))
break;
frame_index = 0;
while (1)
{
/* 枚举这种格式所支持的帧大小 */
memset(&fsenum, 0, sizeof(struct v4l2_frmsizeenum));
fsenum.pixel_format = fmtdesc.pixelformat;
fsenum.index = frame_index;
if (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &fsenum) == 0)
{
printf("format %s,%d, framesize %d: %d x %d\n", fmtdesc.description, fmtdesc.pixelformat, frame_index, fsenum.discrete.width, fsenum.discrete.height);
}
else
{
break;
}
frame_index++;
}
fmt_index++;
}
/* 设置格式 */
struct v4l2_format fmt;
memset(&fmt, 0, sizeof(struct v4l2_format));
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width = 1024;
fmt.fmt.pix.height = 768;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
fmt.fmt.pix.field = V4L2_FIELD_ANY;
if (0 == ioctl(fd, VIDIOC_S_FMT, &fmt))
{
printf("set format ok: %d x %d\n", fmt.fmt.pix.width, fmt.fmt.pix.height);
}
else
{
printf("can not set format\n");
return -1;
}
/*
* 申请buffer
*/
struct v4l2_requestbuffers rb;
memset(&rb, 0, sizeof(struct v4l2_requestbuffers));
rb.count = 32;
rb.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
rb.memory = V4L2_MEMORY_MMAP;
if (0 == ioctl(fd, VIDIOC_REQBUFS, &rb))
{
/* 申请成功后, mmap这些buffer */
buf_cnt = rb.count;
for(i = 0; i < rb.count; i++) {
struct v4l2_buffer buf;
memset(&buf, 0, sizeof(struct v4l2_buffer));
buf.index = i;
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (0 == ioctl(fd, VIDIOC_QUERYBUF, &buf))
{
/* mmap */
bufs[i] = mmap(0 /* start anywhere */ ,
buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
buf.m.offset);
if(bufs[i] == MAP_FAILED) {
perror("Unable to map buffer");
return -1;
}
}
else
{
printf("can not query buffer\n");
return -1;
}
}
printf("map %d buffers ok\n", buf_cnt);
}
else
{
printf("can not request buffers\n");
return -1;
}
/* 把所有buffer放入"空闲链表" */
for(i = 0; i < buf_cnt; ++i) {
struct v4l2_buffer buf;
memset(&buf, 0, sizeof(struct v4l2_buffer));
buf.index = i;
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
{
perror("Unable to queue buffer");
return -1;
}
}
printf("queue buffers ok\n");
/* 启动摄像头 */
if (0 != ioctl(fd, VIDIOC_STREAMON, &type))
{
perror("Unable to start capture");
return -1;
}
printf("start capture ok\n");
/* 创建线程用来控制亮度 */
pthread_t thread;
pthread_create(&thread, NULL, thread_brightness_control, (void *)fd);
while (1)
{
/* poll */
memset(fds, 0, sizeof(fds));
fds[0].fd = fd;
fds[0].events = POLLIN;
if (1 == poll(fds, 1, -1))
{
/* 把buffer取出队列 */
struct v4l2_buffer buf;
memset(&buf, 0, sizeof(struct v4l2_buffer));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (0 != ioctl(fd, VIDIOC_DQBUF, &buf))
{
perror("Unable to dequeue buffer");
return -1;
}
/* 把buffer的数据存为文件 */
sprintf(filename, "video_raw_data_%04d.jpg", file_cnt++);
int fd_file = open(filename, O_RDWR | O_CREAT, 0666);
if (fd_file < 0)
{
printf("can not create file : %s\n", filename);
}
printf("capture to %s\n", filename);
write(fd_file, bufs[buf.index], buf.bytesused);
close(fd_file);
/* 把buffer放入队列 */
if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
{
perror("Unable to queue buffer");
return -1;
}
}
}
if (0 != ioctl(fd, VIDIOC_STREAMOFF, &type))
{
perror("Unable to stop capture");
return -1;
}
printf("stop capture ok\n");
close(fd);
return 0;
}
4.平台信息
开发板：韦东山imx6ull
摄像头：韦东山usb免驱摄像头
涉及软件：
乌班图
vscode
MobaXterm
linux版本：Linux-4.9.88
5.参考记录
博客
正点原子：
【正点原子Linux连载】第二十章 V4L2摄像头应用编程-摘自【正点原子】I.MX6U嵌入式Linux C应用编程指南V1.1_v4l2驱动框架 正点原子-优快云博客
视频
韦东山:
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