-option "filter_num" f "point of filter chain to grab" int typestr="num" default="1" no
-option "slot" s "only grab this slot; grab any slot if negative" int typestr="num" default="-1" no
-option "mode" m "sloppy, pedantic, or aggressive" string typestr="grab_mode" default="sloppy" no
-option "audio_format" a "only grab this type of input stream; grab any if empty" string typestr="name" default="" no
-option "input_grab" i "grab the filter input instead of its output" flag off no
-option "one_shot" o "stop grabbing if audio file changes" flag off no
+option "filter_num" f "point of filter chain to grab" int typestr="num" default="1" optional
+option "slot" s "only grab this slot; grab any slot if negative" int typestr="num" default="-1" optional
+option "mode" m "sloppy, pedantic, or aggressive" string typestr="grab_mode" default="sloppy" optional
+option "audio_format" a "only grab this type of input stream; grab any if empty" string typestr="name" default="" optional
+option "input_grab" i "grab the filter input instead of its output" flag off optional
+option "one_shot" o "stop grabbing if audio file changes" flag off optional