RTcmix Documentation

LPCPLAY

LPCPLAY is used to resynthesize sound based on a pre-existing lpc analysis file. RTcmix has a program included in the distribution -- lpc (in "RTcmix/insts.std/lpc"), but apparently it no longer functions correctly. The better way to create this analysis file is to use Doug Scott's MiXViews program. Luke DuBois wrote some documentation on the older lpc program, as well as the disk-based cmix lpcstuff and lpcplay commands. The newer LPCPLAY supercedes these.

However, documentation is a bit scanty at present. This is from the source code:

/* LPCPLAY - voice resynthesis instrument

   p0 = output start time
   p1 = duration
   p2 = amplitude multiplier
   p3 = pitch factor
   p4 = starting LPC frame
   p5 = ending LPC frame

   // Optional

   p6 = warp            [0 == none]
   p7 = reson cf        [0 == none]
   p8 = reson bw

*/

And there are some additional commands (optional and otherwise), again from the source code:

dataset(p1=dataset name, p2=npoles)
lpcstuff(p0=thresh, p1=random amp, p2=unvoiced rate p3= rise, p4= dec, p5=thresh cutoff)
set_hnfactor(it is a mystery what the param here is...)
freset(and this p-field is also shrouded in the mists of time)
setdev(something about a pitch deviation)
setdevfactor(and oddly enough, this sets a pitch-deviation factor)
set_thresh(go figure...)
use_autocorrect(and this obviously turns on the "autocorrect", eh?)

Now, this might be more useful -- an example scorefile:

/************   LPCPLAY example score *****************/
rtsetparams(44100, 1, 256);
load("LPCPLAY");
bus_config("LPCPLAY", "in 0", "out 0");

/* LPCPLAY arguments: */
/* p0=start,p1=dur,amp,p2=amp,p3=8ve.pch,p4=frame1,p5=frame2,p6=warp,p7=cf,p8=bw, p9/10 --> additional pitch specifications */

float thresh,randamp,fps,frame1,frame2,warp,cf,bw,dur,amp,start,amp
float buzthresh, noisethresh;

/* open the LPC file to be used for the resynthesis */
dataset("/mnt/D/Sounds/lpcfiles/tori02.lpc",0)

/* lpcstuff arguments: */
/* p0=threshold,p1=randamp,p2=unvoiced_at_norm_rate,p3=risetime,p4=decaytime,p5=gain_threshold */

lpcstuff(thresh = .09,  randamp = .1,   0, 0,0,0)

set_thresh(buzthresh = 0.09, noisethresh = 0.1);

fps = 44100/250

frame1=0
frame2=600
warp=0
bw=0
cf=0
amp=10

/* this calculation is just a trick to make 'dur' exactly equal to the */
/* time elapsed between frame1 and frame2 of the lpc data */

dur=(frame2-frame1)/fps

/* straightforward synthesis */
LPCPLAY(start=0,dur,amp,transp = .00001,frame1,frame2,warp,cf,bw)

setdev(1)  /* very slight deviation about base pitch, flat result */
LPCPLAY(start=start+dur+1,dur,amp,transp = 8,frame1,frame2,warp,cf,bw)

setdev(0)  /* back to normal deviation, slower, higher, raise formants */
LPCPLAY(start=start+dur+1,dur*1.5,amp,transp = .08,frame1,frame2,warp=.2,cf,bw)

/* lower, slower, lower formants --sex change operation */
LPCPLAY(start=start+dur*1.5+1,dur*1.5,amp,transp= -.12,frame1,frame2,warp=-.25,cf,bw)

/* even more */
LPCPLAY(start=start+dur*1.5+1,dur*1.5,amp,transp= 6.00,frame1,frame2,warp=-.25,cf,bw)

/* distorted curve, some formant shift, speeding up slightly */
setdev(30)
LPCPLAY(start=start+dur*1.5+1,dur*.9,amp,transp=.02,frame1,frame2,warp=-.1,cf,bw)

/* modify pitch curves */
setdev(0)
LPCPLAY(start=start+dur+1,dur*.9,amp,transp=8,frame1,frame2,warp=0,cf,bw,frame1+50,8,frame1+100,7,frame1+150,7.05,frame2,9)

/* some whispered speech */
lpcstuff(thresh = -.01, randamp = .1,   0,0,0,0)
set_thresh(0.9, 1);
LPCPLAY(start=start+dur+1,dur,amp,transp=8,frame1,frame2,warp=0,cf,bw)

/* highpass whispered speech */
LPCPLAY(start=start+dur+1,dur,amp,transp=8,frame1,frame2,warp=0,cf=5,bw=.1)

/* highpass whispered speech, shift formants */
LPCPLAY(start=start+dur+1,dur,amp,transp=8,frame1,frame2,warp=-.3,cf=7,bw=.05)

/* andrews sisters */
lpcstuff(thresh = .09,  randamp = .1,   0, 0,0,0)
set_thresh(buzthresh, noisethresh);
setdev(15)
amp = 3
LPCPLAY(start=start+dur+1,dur,amp,transp=.01,frame1,frame2,warp=0,cf=0,bw=0)
LPCPLAY(start             ,dur,amp,transp=.05,frame1,frame2,warp=0,cf=0,bw=0)
LPCPLAY(start             ,dur,amp,transp=.08,frame1,frame2,warp=0,cf=0,bw=0)