The mediaplayer is based on the MFAW. Just to give you better understanding
You might want to read about what MFAW is; https://wiki.maemo.org/Documentation...amework_(MAFW)

For the actual command you need to look here: https://wiki.maemo.org/Phone_control#Media_player

There's also an application called phone-control which incorporates many of these commands into simple rememberable ones. https://talk.maemo.org/showthread.php?t=60251