-option "start_time" t "start playback at given time which must be in a:b format where a denotes seconds and b denotes microseconds since the epoch" string typestr="timeval" no
-option "device" d "set PCM device" string typestr="device" default="plughw:0,0" no
-option "channels" c "number of channels (only neccessary for raw audio)" int typestr="num" default="2" no
-option "sample_rate" s "force given sample rate (only neccessary for raw audio)" int typestr="num" default="44100" no
-option "bufsize" b "input buffer size" int typestr="kilobytes" default="64" no
-option "prebuffer" p "delay playback until buffer is filled" int typestr="percent" default="100" no
+option "start_time" t "start playback at given time which must be in a:b format where a denotes seconds and b denotes microseconds since the epoch" string typestr="timeval" optional
+option "device" d "set PCM device" string typestr="device" default="plughw:0,0" optional
+option "channels" c "number of channels (only neccessary for raw audio)" int typestr="num" default="2" optional
+option "sample_rate" s "force given sample rate (only neccessary for raw audio)" int typestr="num" default="44100" optional
+option "bufsize" b "input buffer size" int typestr="kilobytes" default="64" optional
+option "prebuffer" p "delay playback until buffer is filled" int typestr="percent" default="100" optional