ffmpeg -f dshow -video_size 800x800 -framerate 25 -i video="Logitech C270i" -f dshow -i audio="麦克风 (4- USB Audio Device)" -c:v libx264 -preset fast -b:v 3000k -maxrate 3000k -bufsize 6000k -pix_fmt yuv420p -g 60 -c:a aac -b:a 128k -ar 44100 -f flv "rtmp://127.0.0.1:1935/live/vcam"