[FFmpeg error -2]: No such file or directory

[FFmpeg error -2]: No such file or directory 用下面的代码列出USB摄像头，报错 var dict = new MediaDictionary(); dict.Set("list_devices", "true", 0); using FormatContext inFc = FormatContext.OpenInputUrl("video=dummy", InputFormat.FindByShortName("dshow"), dict); inFc.LoadStreamInfo();

就是相当于这个命令 ffmpeg.exe -list_devices true -f dshow -i dummy