关于如何切换为摄像头输入

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环境

• 【系统平台】:
  Linux topeet 4.19.232 Add yolov5 evaluation function #13 SMP Sat Mar 23 16:01:21 CST 2024 aarch64 aarch64 aarch64 GNU/Linux
• 【硬件】： 讯为RK3568开发板
• 【编译语言】： C++
  图片输入模型运行正常，不知道如何切换为板载USB免驱摄像头输入

问题日志及出现问题的操作流程

-[INFO] fastdeploy/runtime/backends/rknpu2/rknpu2_backend.cc(81)::GetSDKAndDeviceVersion rknpu2 runtime version: 1.4.0 (a10f100eb@2022-09-09T09:07:14)
[INFO] fastdeploy/runtime/backends/rknpu2/rknpu2_backend.cc(82)::GetSDKAndDeviceVersion rknpu2 driver version: 0.7.2
index=0, name=x.1, n_dims=4, dims=[1, 640, 640, 3], n_elems=1228800, size=1228800, fmt=NHWC, type=INT8, qnt_type=AFFINE, zp=-128, scale=0.003922, pass_through=0
index=0, name=172, n_dims=4, dims=[1, 255, 80, 80], n_elems=1632000, size=1632000, fmt=NCHW, type=FP32, qnt_type=AFFINE, zp=-128, scale=0.003921, pass_through=0
index=1, name=173, n_dims=4, dims=[1, 255, 40, 40], n_elems=408000, size=408000, fmt=NCHW, type=FP32, qnt_type=AFFINE, zp=-128, scale=0.003921, pass_through=0
index=2, name=174, n_dims=4, dims=[1, 255, 20, 20], n_elems=102000, size=102000, fmt=NCHW, type=FP32, qnt_type=AFFINE, zp=-128, scale=0.003921, pass_through=0
[INFO] fastdeploy/runtime/runtime.cc(367)::CreateRKNPU2Backend Runtime initialized with Backend::RKNPU2 in Device::RKNPU.
[ WARN:0@0.200] imread_('dev21'): can't open/read file: check file path/integrity
[ERROR] fastdeploy/vision/common/processors/pad.cc(30)::ImplByOpenCV Pad: Require input channels equals to size of padding value, but now channels = 1, the size of padding values = 3.
terminate called after throwing an instance of 'cv::Exception'
what(): OpenCV(3.4.20-dev) /home/topeet/opencv/modules/imgproc/src/color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cvtColor'

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求大佬指教