[vlc] Changing the played audio track "on the fly" via http interface

[Olivier DJIAN]

Hi to all,

I wrote some code (actually rpn-designed vlc/html pages) to drive vlc thru his 
http interface. All is fine and now I'd like to add the possibility to change 
the playbacked audio track 'on the fly' (e.g. not using the VLC ui). 

Otherwise said, I need to add some rpn stuff in my vlc/html pages to simulate 
the audio track selection (e.g. via Audio->Track->0..3 in vlc player 
interface or --audio-track option when launching vlc player).

I searched the doc (specially Appendix B) to find a way but didn't succeed. 
Could someone tell me how to achieve this ?
Thanks in advance.

Olivier.