Audio output is a tone related to the striking of a cow bell or similar. The method is a physical model developed from Perry Cook, but re-coded for Csound.
ihrd -- the hardness of the stick used in the strike. A range of 0 to 1 is used. 0.5 is a suitable value.
ipos -- where the block is hit, in the range 0 to 1.
imp -- a table of the strike impulses. The file marmstk1.wav is a suitable function from measurements and can be loaded with a GEN01 table. It is also available at ftp://ftp.cs.bath.ac.uk/pub/dream/documentation/sounds/modelling/.
ivfn -- shape of vibrato, usually a sine table, created by a function.
A note is played on a cowbell-like instrument, with the arguments as below.
kamp -- Amplitude of note.
kfreq -- Frequency of note played.
kvibf -- frequency of vibrato in Hertz. Suggested range is 0 to 12
kvamp -- amplitude of the vibrato
Here is an example of the gogobel opcode. It uses the files gogobel.orc, gogobel.sco, and marmstk1.wav,
Example 15-1. Example of the gogobel opcode.
/* gogobel.orc */
; Initialize the global variables.
sr = 22050
kr = 2205
ksmps = 10
nchnls = 1
; Instrument #1.
instr 1
; kamp = 31129.60
; kfreq = 440
; ihrd = 0.5
; ipos = 0.561
; imp = 1
; kvibf = 6.0
; kvamp = 0.3
; ivfn = 2
a1 gogobel 31129.60, 440, 0.5, 0.561, 1, 6.0, 0.3, 2
out a1
endin
/* gogobel.orc */
/* gogobel.sco */
; Table #1, the "marmstk1.wav" audio file.
f 1 0 256 1 "marmstk1.wav" 0 0 0
; Table #2, a sine wave for the vibrato.
f 2 0 128 10 1
; Play Instrument #1 for one second.
i 1 0 1
e
/* gogobel.sco */