Number of slices, used in parallelized encoding.
@item thread_type @var{flags} (@emph{decoding/encoding,video})
-Select multithreading type.
+Select which multithreading methods to use.
+
+Use of @samp{frame} will increase decoding delay by one frame per
+thread, so clients which cannot provide future frames should not use
+it.
Possible values:
@table @samp
@item slice
+Decode more than one part of a single frame at once.
-@item frame
+Multithreading using slices works only when the video was encoded with
+slices.
+@item frame
+Decode more than one frame at once.
@end table
+
+Default value is @samp{slice+frame}.
+
@item audio_service_type @var{integer} (@emph{encoding,audio})
Set audio service type.