1.ffmpeg查看电脑设备
输入以下指令
ffmpeg -list_devices true -f dshow -i dummy
打印以下结果

[dshow @ 000001ef0ba48980] DirectShow video devices (some may be both video and audio devices)
[dshow @ 000001ef0ba48980]  "HD Pro Webcam C920"
[dshow @ 000001ef0ba48980]     Alternative name "@device_pnp_\\?\usb#vid_046d&pid_0892&mi_00#6&23200a34&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
[dshow @ 000001ef0ba48980]  "YY开播
[dshow @ 000001ef0ba48980]     Alternative name "@device_sw_{860BB310-5D01-11D0-BD3B-00A0C911CE86}\yyanchorvcam"
[dshow @ 000001ef0ba48980]  "x9shows_camera"
[dshow @ 000001ef0ba48980]     Alternative name "@device_sw_{860BB310-5D01-11D0-BD3B-00A0C911CE86}\{01010101-1212-2323-3434-454545454545}"
[dshow @ 000001ef0ba48980]  "OBS-Camera"
[dshow @ 000001ef0ba48980]     Alternative name "@device_sw_{860BB310-5D01-11D0-BD3B-00A0C911CE86}\{27B05C2D-93DC-474A-A5DA-9BBA34CB2A9C}"
[dshow @ 000001ef0ba48980]  "OBS-Camera2"
[dshow @ 000001ef0ba48980]     Alternative name "@device_sw_{860BB310-5D01-11D0-BD3B-00A0C911CE86}\{27B05C2D-93DC-474A-A5DA-9BBA34CB2A9D}"
[dshow @ 000001ef0ba48980]  "OBS-Camera3"
[dshow @ 000001ef0ba48980]     Alternative name "@device_sw_{860BB310-5D01-11D0-BD3B-00A0C911CE86}\{27B05C2D-93DC-474A-A5DA-9BBA34CB2A9E}"
[dshow @ 000001ef0ba48980]  "OBS-Camera4"
[dshow @ 000001ef0ba48980]     Alternative name "@device_sw_{860BB310-5D01-11D0-BD3B-00A0C911CE86}\{27B05C2D-93DC-474A-A5DA-9BBA34CB2A9F}"
[dshow @ 000001ef0ba48980] DirectShow audio devices
[dshow @ 000001ef0ba48980]  "icon(3- USB AUDIO  CODEC)"

2使用ffplay播放设备

ffplay -f dshow -i video="HD Pro Webcam C920"  

或者

ffplay -f vfwcap -i 0

如果输入命令后没有反应证明你没有配置ffmpeg变量 或不在ffmpeg目录下