It was originally adapted from Perry Cook and Gary Scavone's STK, the Synthesis ToolKit for doing amazing physical model stuff.
Here's what Perry says about "Brass":
/* MSITAR - the "Sitar" physical model instrument in
Perry Cook/Gary Scavone's "stk" (synthesis tookkit).
p0 = output start time
p1 = duration
p2 = amplitude multiplier
p3 = frequency (Hz)
p4 = pluck amp (0.0-1.0)
p5 = percent of signal to left output channel [optional, default is .5]
Assumes function table 1 is amplitude curve for the note.
Or you can just call setline. If no setline or function table 1, uses
flat curve.
*/
Sample scorefile:
rtsetparams(44100, 2)
load("MSITAR")
makegen(1, 24, 1000, 0,1, 1,1)
MSITAR(0, 3.5, 10000, cpspch(8.00), 0.9)
MSITAR(4, 3.5, 10000, cpspch(8.07), 0.9)