COMPLIMIT

Compress/limit an input signal.

in RTcmix/insts/jg

quick syntax:

COMPLIMIT(outsk, insk, dur, PREAMP, POSTAMP, ATTACK, RELEASE, THRESHOLD, COMPRESSRATIO, lookahead, windowsize[, DETECTIONTYPE, BYPASS, 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 duration seconds no no    
p3 gain applied to input before compression dBFS yes no 0 means no change  
p4 gain applied to output after compression - “makeup gain” dBFS yes no    
p5 attack time seconds yes no    
p6 release time seconds yes no    
p7 threshold dBFS yes no    
p8 compression ratio >0 yes no 20 means 20:1 (100 is infinity)
p9 look-ahead time seconds no no    
p10 peak detection window size power of 2* no no * must be <= RTCmix output buffer size  
p11 detection type 0: peak, 1: average peak, 2: rms yes yes default: 0  
p12 bypass 0: bypass off, 1: bypass on yes yes default: 0  
p13 input channel - yes yes default: 0  
p14 pan 0-1 stereo; 0.5 is middle yes yes default: 0.5  

Parameters labled as Dynamic can receive dynamic updates from a table or real-time control source.

Author: John Gibson , 4/21/00; rev. for v4, 6/18/05

COMPLIMIT applies dynamic compression or limiting to an audio signal

Usage Notes

For information about how compression/limiting works, look for articles on the web. The parameters of this instrument are fairly standard.

One minor problem: sometimes the compressor will stay in sustain for too long. This happens when the source sound has a long decaying envelope where some of the decay is above the threshold.

COMPLIMIT can produce stereo or mono output.

Sample Scores

very basic:

   rtsetparams(44100, 2)
   load("COMPLIMIT")
   
   rtinput("mysound.aif")

   inskip = 1
   dur = 5
   
   ingain = 0
   outgain = 0
   attack = 0.01
   release = 0.06
   threshold = -10
   ratio = 100
   lookahead = attack
   windowlen = 128
   detect_type = 0
   bypass = 0
   
   outskip = 0
   COMPLIMIT(outskip, inskip, dur, ingain, outgain, attack, release, threshold,
             ratio, lookahead, windowlen, detect_type, bypass, inchan=0, pctleft=.5)

slightly more advanced:

   rtsetparams(44100, 2)
   load("COMPLIMIT")
   
   rtinput("mysound.aif")
   inskip = 0
   dur = DUR()
   
   ingain = 18
   outgain = 0
   attack = 0.001
   release = 0.02
   threshold = -20
   ratio = 4
   lookahead = attack
   windowlen = 128
   detect_type = 0
   bypass = 0
   
   COMPLIMIT(0, inskip, dur, ingain, outgain, attack, release, threshold,
      ratio, lookahead, windowlen, detect_type, bypass, inchan=0, pan=.5)

See Also

DECIMATE, DISTORT, SHAPE, DCBLOCK