Reminder that this ffmpeg filter will create a cross-eye video from oculus mirror capture
-vf "split [left][right];[left]crop=w=iw/2:h=ih:x=0:y=0[lefthalf];[right]crop=w=iw/2:h=ih:x=iw/2:y=0[righthalf];[righthalf][lefthalf]hstack"