linux 查找摄像头列表以及可用分辨率 c++代码-DPDK中文网

要在Linux中查找摄像头列表及其支持的可用分辨率，您可以使用V4L2（Video for Linux 2）API。以下是一个示例代码，它不仅列出可用的视频设备，还显示每个设备支持的分辨率。

C++ 示例代码

#include <iostream>
#include <string>
#include <fcntl.h>
#include <linux/videodev2.h>
#include <sys/ioctl.h>
#include <unistd.h>

void listVideoDevices() {
    const std::string devicePrefix = "/dev/video";
    
    for (int i = 0; i < 10; ++i) { // 假设最多有10个视频设备
        std::string devicePath = devicePrefix + std::to_string(i);
        int fd = open(devicePath.c_str(), O_RDONLY);

        if (fd == -1) {
            continue; // 如果设备不存在，则继续
        }

        struct v4l2_capability cap;
        if (ioctl(fd, VIDIOC_QUERYCAP, &cap) == 0) {
            std::cout << "Device: " << devicePath << "\n";
            std::cout << "  Driver: " << cap.driver << "\n";
            std::cout << "  Card: " << cap.card << "\n";
            std::cout << "  Bus info: " << cap.bus_info << "\n";
            std::cout << "  Version: "
                      << ((cap.version >> 16) & 0xFF) << "."
                      << ((cap.version >> 8) & 0xFF) << "."
                      << (cap.version & 0xFF) << "\n";

            // 查询格式支持情况
            struct v4l2_fmtdesc fmtDesc;
            fmtDesc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

            std::cout << "Supported formats:\n";
            while (ioctl(fd, VIDIOC_ENUM_FMT, &fmtDesc) == 0) {
                std::cout << " - Format: " 
                          << fmtDesc.description 
                          << " (" 
                          << fmtDesc.pixelformat 
                          << ")" 
                          << "\n";

                // 查询该格式下的可用分辨率
                struct v4l2_frmsizeenum frmSizeEnum;
                frmSizeEnum.pixel_format = fmtDesc.pixelformat;

                while (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &frmSizeEnum) == 0) {
                    if (frmSizeEnum.type == V4L2_FRMSIZE_TYPE_DISCRETE) {
                        std::cout << "   Discrete size: "
                                  << frmSizeEnum.discrete.width 
                                  << "x" 
                                  << frmSizeEnum.discrete.height 
                                  << "\n";
                    } else if (frmSizeEnum.type == V4L2_FRMSIZE_TYPE_STEPWISE) {
                        std::cout<< "   Stepwise sizes from "
                                 << frmSizeEnum.stepwise.min_width 
                                 <<"x" 
                                << frmSizeEnum.stepwise.min_height  
                                 <<" to "
                                 <<"Max Size:"  
                                 <<"Width:"
                                 /* Add more information about stepwise format here */
                                ;
                    }
                    
                    ++frmSizeEnum.index;
                }

                ++fmtDesc.index;
            }
            
        } else {
            std::cerr<< "[ERROR] Failed to query capabilities for "<< devicePath<<"\n";  
        }

        close(fd);
    }
}

int main() {
    listVideoDevices();
    return 0;
}

编译与运行

保存代码到 list_video_devices.cpp 文件中。

编译：


g++ list_video_devices.cpp -o list_video_devices

运行：
```
./list_video_devices
```

注意事项

确保您的系统安装了必要的开发工具和库，通常需要安装 libv4l-dev 包：
```
sudo apt-get install libv4l-dev
```
权限问题：访问 /dev/video* 的权限可能需要使用 sudo。
此示例假设最多有10个视频设备，如果你的系统上有更多设备，请调整循环的范围。

内容由零声教学AI助手提供，问题来源于学员提问