ffmpeg -y -f x11grab -s 1920x1080 -framerate 30 -i :0 -f pulse -i alsa_output.pci-0000_00_1b.0.analog-stereo.monitor -vf 'setpts=(RTCTIME-RTCSTART)/(TB*1000000)' -af asetpts=N/SR/TB,apad -shortest -c:v libx264 -profile:v high444 -preset:v veryfast -qp:v 0 -pix_fmt yuv444p -c:a flac screencast.mkv
获取音频：
pactl list | grep -A2 'Source #'
Source #0
State: IDLE
Name: alsa_output.pci-0000_00_1b.0.analog-stereo.monitor
--
Source #1
State: SUSPENDED
Name: alsa_input.pci-0000_00_1b.0.analog-stereo