Am Mo., 13. Aug. 2018 um 12:48 Uhr schrieb Ceresa Jean-Jacques <address@hidden
>Is it possible to do that from calling libfluidsynth library functions?
Yes it is, using fluid_synth_cc() function and sending a CC 10 (panoramic) as described by previous Tom's awswer.
Using CC 8 might be better for your purpose, as that will also work properly with stereo samples. But it requires that you use fluidsynth >= 2.0.
CC 10 (Panning) with stereo samples simply shifts the perceived source of the sound left or right a little bit but doesn't mute one channel completely as CC 8 (Balance) does.