How to control the media player in diablo or chinook, from the network:

I use my n800 as upnp client, it's plugged to my stereo. the upnp server, coherence (great) is on my server which is always on.

Problem, the stereo is much too far from the sofa and I usually prefer to stay on my sofa rather than having to stand up everytime I want to change tracks, change volume etc..

media player does not use dbus when switching to next track. so I did not find a documented way to control the media player.
by connecting to /tmp/mediaplayer-engine.socket, it's possible to send commands or read status, song information,, etc..

Install socat, it's used to reroute one unix stream to another. great tool.
so.. on the nokia device, reroute a tcp socket to this unix socket /tmp/mediaplayer-engine.socket:

socat -v tcp-l:6666,reuseaddr,fork unix:/tmp/mediaplayer-engine.socket

from my sofa (running linux of course)

echo "next" | socat - tcp:ip_nokia:6666
or if you prefer netcat (available on windows too)
echo "next" | nc ip_nokia 6666

other commands (do the same with | nc ip_nokia 6666)

• echo "get_position" : read position in milliseconds
• echo "get_current" : read the current url, example:
  upnpav:///Coherence%20MediaStore/Artists/Caf%C3%A9%20del%20Mar/All%20tracks%20of%20Caf%C3%A9%20del%20Mar/Sabres%20Of%20Paradise%20/%20Smokebelch%20II.mp3
• echo "getcurrent_idx" : get track number in the playlist
• echo "getmax_idx" : get number of tracks in the playlist
• echo -e "get_stream_details\ntitle": get title
• echo -e "get_stream_details\nartist": get artist
• echo -e "get_stream_details\nalbum": get album
• echo -e "get_stream_details\ngenre": get genre
• echo "get_volume": get volume of media player, from 0 to 100
• echo "get_stream_buffer_state": get percentage filling of stream buffer from 0 to 100
• echo "pause" : play current selected song (return 0 if it was already paused)
• echo "play" : play or resume
• echo "stop" : stop
• echo "next" : go to next track in playlist
• echo "prev" : go to previous track in playlist
• echo -e "volume\n42" : set volume to 42%

There are others but these are the most important.