我输入的命令是:ffmpeg -f avfoundation -i 1 -r 30 out.yuv
然后报错
[AVFoundation input device @ 0x7ffb59500500] Invalid device index
1: Input/output error
D avfoundation AVFoundation input device
D lavfi Libavfilter virtual input device
E sdl,sdl2 SDL2 output device
问下老师这是什么原因?