audio output selection.
 

i dont know what the technical term for this would be, but is it possible to get BS player to choose which speakers to output to? i have 4 speakers plugged upto my SBLive soundcard, eg front & rear, both to independent speakers, so could i make it so the movie sound only comes out the rear speakers? and have the front speakers for something else such as a game or music?

does this make sense, or already possible? thanks.

not really
 

With the bundled software that comes with most sound cars it is possible to fade all the sound so it only comes out the back, but you can't make something different come out the front. I think it would possible, techically, to achieve this is both your audio streams were Dolby 5.1, but only acutally had sound some of the tracks (so stream A only had sound on the front two tracks and stream B on the back two). When the sound card mixed the audio sources it would achieve your goal. But BSPlayer does not support this kind of 5.1 emulation and neither does any game or any audio player (I think). Every program that I know of would fill both the front and back channels with the same data, if it were emulating 5.1

plugin
 

I haven't looked at the plugin api, but you might be able to write a plugin to due this.