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FireFly 板子（新 USB 摄像头调试记录）

本贴最后更新于 238 天前，其中的信息可能已经事过景迁

一、基础信息

​image​

‍

二、可用的 GPIO 管脚

​image​

三、折腾摄像头端

首先 mipi 摄像头会干扰 uvc 的设备节点，因此先将 mipi 摄像头硬件卸载下来。

3.1、将 usb 摄像头硬件摸清楚

  • 将 usb 摄像头插入板子，查看枚举信息：

​lsusb​


Bus 006 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 003: ID 0bda:c820 Realtek Semiconductor Corp. USB 2.0 Hub [MTT]
Bus 002 Device 002: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 002: ID 1bcf:2cd1 Sunplus Innovation Technology Inc. DECXIN  CAMERA
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

r 如上图，Bus 001 Device 002: ID 1bcf:2cd1 Sunplus Innovation Technology Inc. DECXIN CAMERA ​已经枚举出来了

  • 使用 v4l2-ctl 工具查看必要信息，通过 ** **ls /dev/video*** ** 不难发现其实 /dev/video40 才是所需要的节点

​v4l2-ctl​ 是一个 Linux 命令行工具，用于控制视频 4 Linux 设备，包括摄像头。通过这个工具，您可以查看和修改摄像头的各种设置，例如亮度、对比度、曝光等。

以下是一些常用的 v4l2-ctl​ 命令示例：

列出设备信息：
​v4l2-ctl --list-devices​

这个命令会列出系统中可用的视频设备，包括摄像头，以及每个摄像头的设备名称和相关信息。

查看当前设备的设置：
​v4l2-ctl -d /dev/video0 --list-ctrls​

这个命令会列出 /dev/video0​ 设备的可调节控制参数，比如亮度、对比度、饱和度等。

获取特定控制参数的当前值：
​v4l2-ctl -d /dev/video0 --get-ctrl=exposure_auto​

这个命令会显示摄像头曝光模式的当前设置。

设置特定控制参数的值：
​v4l2-ctl -d /dev/video0 --get-ctrl=exposure_auto​

这个命令会将摄像头的曝光模式设置为自动。

要查看摄像头支持的分辨率，

​v4l2-ctl --list-formats-ext​


firefly@firefly:~/Desktop$ v4l2-ctl -d /dev/video40 --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
        Type: Video Capture

        [0]: 'MJPG' (Motion-JPEG, compressed)
                Size: Discrete 1920x1200
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1600x1200
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1280x960
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1024x768
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 960x720
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 800x600
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 640x480
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 320x240
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
        [1]: 'YUYV' (YUYV 4:2:2)
                Size: Discrete 1920x1200
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1600x1200
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1280x960
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 1024x768
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 960x720
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 800x600
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 640x480
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
                Size: Discrete 320x240
                        Interval: Discrete 0.011s (90.000 fps)
                        Interval: Discrete 0.017s (60.000 fps)
                        Interval: Discrete 0.033s (30.000 fps)
                        Interval: Discrete 0.040s (25.000 fps)
                        Interval: Discrete 0.050s (20.000 fps)
                        Interval: Discrete 0.067s (15.000 fps)
                        Interval: Discrete 0.100s (10.000 fps)
                        Interval: Discrete 0.200s (5.000 fps)
  • 快速使用 python 来捕获视频保存本地并 load 到 windows 端查看

必须安装必要工具 ： sudo apt-get install python3-opencv​

使用脚本：注意是 MJPG 格式（比较常用）

import cv2

# 使用摄像头设备索引号初始化摄像头
# 通常，第一个摄像头设备的索引号为0，第二个为1，以此类推,我们用的是40
cap = cv2.VideoCapture(40)

# 检查摄像头是否正确打开
if not cap.isOpened():
    print("无法打开摄像头")
    exit()

# 获取视频帧的宽度和高度
frame_width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
frame_height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

# 定义视频编解码器并创建 VideoWriter 对象
fourcc = cv2.VideoWriter_fourcc(*'MJPG')
out = cv2.VideoWriter('output.avi', fourcc, 20.0, (frame_width, frame_height))

# 不断循环，读取视频帧并写入输出视频文件
while True:
    # 从摄像头捕获一帧图像
    ret, frame = cap.read()

    # 如果帧读取失败，则退出循环
    if not ret:
        print("无法读取帧")
        break

    # 将帧写入输出视频文件
    out.write(frame)

    # 检测键盘输入，按下ESC键退出循环
    if cv2.waitKey(1) == 27:
        break

# 释放摄像头资源、关闭输出视频文件并关闭所有窗口
cap.release()
out.release()
cv2.destroyAllWindows()

运行后得到：output.avi （注意强制停止，否则视频文件很大）

​image​

至此，使用 python 验证了 uvc 是可行的，并且使用 v4l2-ctl 工具验证了部分相机参数是可以被设置的，因此进入写 c++ 代码实现环节

3.2、代码实现

  • 准备开发的软件环境

    • 安装库，sudo apt-get install libopencv-dev

    • 编写代码和 makefile

      • makefile 中一般使用 pkg-config 来管理 opencv 的一些编译相关内容
      • 但后面发现根本不是从 pkg 来安装 opencv 的，无法找到 opencv.pc locate opencv.pc ​命令是空的

    • 改 makefile，不需要 pkg 来配置

源代码：

#include <opencv2/opencv.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main() {
    // 打开摄像头
    VideoCapture cap(40);

    // 检查摄像头是否正确打开
    if (!cap.isOpened()) {
        cout << "无法打开摄像头" << endl;
        return -1;
    }

    // 获取摄像头的默认分辨率
    int frame_width = cap.get(CAP_PROP_FRAME_WIDTH);
    int frame_height = cap.get(CAP_PROP_FRAME_HEIGHT);

    // 定义视频编解码器并创建 VideoWriter 对象
    VideoWriter video("output.avi", VideoWriter::fourcc('M', 'J', 'P', 'G'), 20, Size(frame_width, frame_height));

    // 检查视频文件是否成功打开
    if (!video.isOpened()) {
        cout << "无法创建视频文件" << endl;
        return -1;
    }

    // 不断循环，读取视频帧并写入输出视频文件
    while (true) {
        Mat frame;
        // 从摄像头捕获一帧图像
        cap >> frame;

        // 如果帧读取失败，则退出循环
        if (frame.empty()) {
            cout << "无法读取帧" << endl;
            break;
        }

        // 将帧写入输出视频文件
        video.write(frame);

        // 检测键盘输入，按下ESC键退出循环
        if (waitKey(1) == 27) {
            break;
        }
    }

    // 释放摄像头资源、关闭输出视频文件
    cap.release();
    video.release();

    return 0;
}

Makefile 文件：

CC=g++

CFLAGS=-std=c++11
LIBS=-lopencv_core -lopencv_highgui -lopencv_videoio -lopencv_imgproc
INCLUDE=-I/usr/include/opencv4
LIBRARY=-L/usr/lib//aarch64-linux-gnu

all: capture_video

capture_video: capture_video.cpp
	$(CC) $(CFLAGS) -o capture_video capture_video.cpp  $(INCLUDE) $(LIBRARY) $(LIBS)

clean:
	rm -f capture_video

运行截图：

​image​

​image​

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