Brass instrument physical model.
in RTcmix/insts/stk
MBRASS(outsk, dur, AMP, FREQ, SLIDELEN, LIPFILT, maxpressure[, PAN, BREATHENV])
CAPITALIZED parameters are pfield-enabled for table or dynamic control (see the maketable or makeconnection scorefile commands). Parameters after the [bracket] are optional and default to 0 unless otherwise noted.
| Param Field | Parameter | Units | Dynamic | Optional | Notes |
|---|---|---|---|---|---|
| p0 | output start time | seconds | no | no | |
| p1 | duration | seconds | no | no | |
| p2 | amplitude | absolute, for 16-bit soundfiles: 0-32768 | yes | no | |
| p3 | frequency | Hz | yes | no | |
| p4 | slide length | samps | yes | no | |
| p5 | lip filter | Hz | yes | no | |
| p6 | max pressure | 0.0-1.0 | no | no | |
| p7 | pan | 0-1 stereo; 0.5 is middle | yes | yes | default: 0.5 |
| p8 | breath pressure envelope | reference to a pfield table-handle | yes | yes | if 0, value defaults to 1.0 |
Parameters labled as Dynamic can receive dynamic updates from a table or real-time control source.
Author: Brad Garton, based on code from the Synthesis ToolKit
MBRASS is the “Brass” physical model in Perry Cook and Gary Scavone’s STK, the Synthesis ToolKit.
MBRASS models a simple brass instrument, using digital waveguide techniques. Dum-dah-dah-DAAAAAH! Here’s what Perry says about “Brass”:
Although parameter p3 (“FREQ”) looks as though it would set the pitch for MBRASS, it is only one element of several interacting factors. This is a physical model, and as such the sounding pitch is influenced by the length of the modeled tube/slide (p4, “SLIDELEN”), the ‘lip filter’ modeling how elastic the lip-impulse sound is (p5, “LIPFILT”) and the simulated air pressure in the model (p6, “maxpressure” and p8, “BREATHENV”). In other words, specifying a particular pitch is somewhat inexact. Here is a rough tuning-table (done by ear!) for the MBRASS instrument:
note (oct.pc) slide length (p4) lip filter (p5) max pressure (p6)
7.00 103 140 0.045
7.01 103 150 0.05
7.02 103 160 0.07
7.03 103 170 0.1
7.04 100 180 0.1
7.05 95 188 0.15
7.06 90 195 0.15
7.07 80 207 0.2
7.08 75 220 0.2
7.09 70 235 0.2
7.10 65 250 0.2
7.11 55 255 0.2
8.00 50 265 0.2
8.01 45 280 0.2
8.02 43 295 0.2
8.03 40 320 0.1
8.04 40 340 0.25
8.05 35 355 0.25
8.06 30 370 0.25
8.07 30 395 0.3
8.08 25 415 0.3
8.09 15 430 0.3
8.10 10 450 0.3
8.11 10 480 0.2
8.11 (alt) 270 450 0.23
9.00 10 520 0.2
9.00 (alt) 255 480 0.23/0.25
9.01 240 490 0.3
9.02 228 530 0.3
9.03 215 550 0.35
9.04 202 590 0.4
9.05 190 640 0.4
9.06 180 670 0.45
9.07 170 710 0.5
9.08 160 740 0.55
9.09 150 780 0.6
9.10 142 840 0.6
9.11 134 860 0.65
10.00 127 940 0.7
These are approximate. Also note that the same pitch may be produced by different combinations of parameters.
Also be aware that some combinations of parameters will yield no sound. The ‘physics’ have to work correctly!
MBRASS can produce other mono or stereo output.
very basic:
rtsetparams(44100, 2)
load("MBRASS")
amp = 40000
breathenv = maketable("line", 1000, 0,0, 0.05,1, 3.0,3, 3.5,0)
MBRASS(0, 3.5, amp, 249.0, 200, 279.0, 0.3, 0.5, breathenv)
MBRASS(4, 3.5, amp, 249.0, 400, 279.0, 0.3, 0.5, breathenv)
slightly more advanced:
rtsetparams(44100, 2)
load("MBRASS")
freq = maketable("line", "nonorm", 1000, 0,201, 1,314)
pan = makeLFO("tri", 0.5, 0.0, 1.0)
MBRASS(0, 3.5, 15000, freq, 200, 279.0, 0.3, pan)
bamp = maketable("line", 1000, 0,0, 1,1, 2,0)
slide = maketable("line", "nonorm", 1000, 0, 100, 1, 400, 3, 200)
lipfilt = makeLFO("sine", 3.5, 250, 400)
MBRASS(4, 3.5, 20000, 249.0, slide, lipfilt, 0.3, 0.5, bamp)
fun stuff!
rtsetparams(44100, 2)
load("MBRASS")
srand()
breathamp = maketable("line", 1000, 0,0, 5,1, 10,0)
/* amps */
amps = { 30000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000, 20000 }
lamps = len(amps)
/* pch */
pches = { 7.05, 7.07, 7.10, 8.00, 8.02, 8.03, 8.05, 8.07, 8.09, 8.10, 9.00, 9.02, 9.03, 9.05, 9.07, 9.09, 9.10, 10.00 }
/* slide length */
slidelen = { 95, 80, 65, 50, 43, 40, 35, 30, 15, 10, 255, 228, 215, 190, 170, 150, 142, 127 }
/* lip filter */
lipfilt = { 188, 207, 250, 265, 295, 320, 355, 395, 430, 450, 480, 530, 550, 640, 710, 780, 840, 940 }
/* max pressure */
maxpress = { 0.15, 0.2, 0.2, 0.2, 0.2, 0.2, 0.25, 0.3, 0.3, 0.3, 0.25, 0.3, 0.35, 0.4, 0.5, 0.6, 0.6, 0.7 }
start = 0
for(i = 0; i < 100; i=i+1)
{
index = trand(0, lamps)
amp = amps[index]
pch = pches[index]
slide = slidelen[index]
lip = lipfilt[index]
pressure = maxpress[index]
dur = irand(1.7, 2.7)
MBRASS(start, dur, amp*0.4, cpspch(pch), slide, lip, pressure, random(), breathamp)
start = start + (random() * 0.2 + 0.1)
}
maketable, CLAR, MBLOWBOTL, MBLOWHOLE, MBOWED, MCLAR, METAFLUTE, MSAXOFONY, MSITAR