-command-line tool because the audio and video data will be encoded only once
-with the tee muxer; encoding can be a very expensive process. It is not
-useful when using the libavformat API directly because it is then possible
-to feed the same packets to several muxers directly.
+command-line tool. With the tee muxer, the audio and video data will be encoded only once.
+With conventional multiple outputs, multiple encoding operations in parallel are initiated,
+which can be a very expensive process. The tee muxer is not useful when using the libavformat API
+directly because it is then possible to feed the same packets to several muxers directly.
+
+Since the tee muxer does not represent any particular output format, ffmpeg cannot auto-select
+output streams. So all streams intended for output must be specified using @code{-map}. See
+the examples below.
+
+Some encoders may need different options depending on the output format;
+the auto-detection of this can not work with the tee muxer, so they need to be explicitly specified.
+The main example is the @option{global_header} flag.
+
+The slave outputs are specified in the file name given to the muxer,
+separated by '|'. If any of the slave name contains the '|' separator,
+leading or trailing spaces or any special character, those must be
+escaped (see @ref{quoting_and_escaping,,the "Quoting and escaping"
+section in the ffmpeg-utils(1) manual,ffmpeg-utils}).
+
+@subsection Options