the /home directory, where all the media is stored, is mounted on all the media directors. Normally, when you go to play music on a media director, slim server isn't used. Xine just gets a 'play' command, and plays the file off the local mount.
However, if the destination is multiple xine's, then it's not advisable to have both of them play the files individually -- they will be out of sync. So, media plugin has the logic that says: if the destination is a single xine, send that xine a play. if the destination is a single network audio player (like the squeeze box which can't 'play' media that's not streamed), or if the destination is multiple xines, or a combination of a xine and a squeeze box, then rather than xine the play, it starts the slim server streaming the audio.
Then it sends all the target devices (xine, and squeezebox) a command to play what is being broadcast over a given port.
What I'm not totally understanding is the desire to run multiple xine's. We never tried running more than 1. If you want 10 zones of audio in your house, and have 2 media directors, than those 2 m/d's can be 2 of your zones, and you can add 8 network audio players, like the squeeze boxes, which cost around $150 for the other zones.
You mention running 5 xine instances on a single computer. Is the intention that you will put 5 sound cards in the computer, and have each xine running to a sound card, and the goal is to have 5 'zones' of audio?
You mention 'multichannel', and I'm not sure if we're talking the same thing or not... When I think of multi-channel, I think of multiple audio channels within a given stream. Like dolby digital 5.1. That doesn't require multiple xines, or multiple sound cards. The single xine player gets the single audio/video stream which contains 5+1 channels of audio and plays it.
When I think of multiple xine's, I'm assuming you're referring to, what we call multi-zone, rather than multi-channel. Multii-zone meaning I want to be playing Metallica in Zone 1, Mozart in Zone 2, and iRobot in Zone 3. The channels are not important--Zone 1 may be stereo, Zone 2 may be 4 channel audio from an SACD, and Zone 3 may be 6+1 channel.
But when you talk about running 5 xine's, which I assume means 5 different zones, the only way that would make sense to me is if you have 5 separate sound cards. If there's only 1 sound card, what would the 5 different xine's render their audio to?
So, assuming you mean 5 xine's and 5 sound card's, so that you can 5 zones of music with 1 pc, it should be possible, theoretically, although we haven't tried it. Since the squeeze boxes are fairly cheap, we figured that rather than buying 5 sound cards, it would be easier to buy 5 squeeze boxes.
Let me know the intended purpose, so I can be sure we're talking the same thing.