+
+@item size
+Set size of frame in number of samples which will be processed at once.
+Default value is @var{1024}. Allowed range is from 1024 to 96000.
+
+@item hrir
+Set format of hrir stream.
+Default value is @var{stereo}. Alternative value is @var{multich}.
+If value is set to @var{stereo}, number of additional streams should
+be greater or equal to number of input channels in first input stream.
+Also each additional stream should have stereo number of channels.
+If value is set to @var{multich}, number of additional streams should
+be exactly one. Also number of input channels of additional stream
+should be equal or greater than twice number of channels of first input
+stream.