Bit-reduce an input signal.
in RTcmix/insts/jg
DECIMATE(outsk, insk, dur, PREAMP, POSTAMP, NBITS[, LOWPASSFREQ, inputchan, PAN])
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 | input start time | seconds | no | no | |
| p2 | input duration | seconds | no | no | |
| p3 | pre-amp multiplier (before decimation) | relative multiplier | yes | no | |
| p4 | post-amp multiplier (after decimation) | relative multiplier | yes | no | |
| p5 | number of bits to use | 1 to 16 | yes | no | |
| p6 | low-pass filter cutoff frequency | Hz | yes | yes | default: 0 (will bypass) |
| p7 | input channel | - | no | yes | default: 0 |
| p8 | pan | 0-1 stereo; 0.5 is middle | yes | yes | default: 0 |
Parameters labled as Dynamic can receive dynamic updates from a table or real-time control source.
Author: JGG, 3 Jan 2002, rev for v4, 7/11/04
DECIMATE reduces the number of bits in the input audio signal
DECIMATE reduces the number of bits used to represent the amplitude of individual samples. The sound quality will be altered as a result
The optional low-pass filter (p5 > 0) is a simple butterworth filter design. The cutoff frequency may be modulated dynamically.
The “PREAMP” (p3) and “POSTAMP” (p4) parameters allow you to adjust the alteration in amplitude resulting from the bit-rediction.
The output of DECIMATE can be either mono or stereo.
very basic:
rtsetparams(44100, 2)
load("DECIMATE")
rtinput("mysound.aif")
bits = 2
cutoff = 4000
dur = DUR()
amp = 1
ampenv = maketable("line", 1000, 0,0, 1,1, 5,1, 10,0)
DECIMATE(0, 0, dur, 1, amp*ampenv, bits, cutoff)
slightly more advanced:
rtsetparams(44100, 2)
load("DECIMATE")
rtinput("mysound.aif")
inchan = 0
dur = DUR()
bits = 2
preamp = 2
postamp = maketable("line", 1000, 0,0, 5,1, 9,1, 10,0)
cutoff = maketable("line", "nonorm", 1000, 0,1, 1,10000, 2,800)
pan = maketable("line", 100, 0,0, 1,1)
DECIMATE(0, 0, dur, preamp, 0.9*postamp, bits, cutoff, inchan, pan)