Variables and their meanings are:
srate The sampling rate of the output waveform (Hz). NB This should not be changed from the default of 20kHz without changing the Digital filters.
frate The frame rate (Hz). The number of frames of input per second. Default 100 Hz.
cratef The Glottal function sampling rate. Default 5000 Hz.
cratex Excitation sub-frame rate (Normally a tenth of srate ). Default 2000 Hz.
fqlow, fqstep Values for calculating the frequencies at which entries in the cosine table for formant generators are calculated. F = fqlow + n * fqstep, n = 0..255.
bwlow, bwstep The exponent table used in the formant generator is calculated using frequencies F = bwlow + n * bwstep, n = 0..31.
foscal, fobase Values for calculating the excitation pitch table. Excitation frequencies are F = foscal * ( fobase ** ( n/16)), n = 0..63. These correspond with the control values 0..254.
dbstep Separation in decibels of amplitude controls. ie value I 0..63 gives an amplitude of 10**( (I-63) * dbstep / 20). Default value 1 dB.
aoffdn, foffdn, scaldn Used to calculate the degree of nasality for any given ALF, A1 and F1 control values. aoffdn is in decibels, foffdn in Hertz, scaldn is a scale factor. These are combined to give the degree of nasality in the following formula. Dnasal = ( max (0, ALF-A1-aoffdn) * max (0, F1-foffdn) ) / scaldn
conts contant component of glottal pulse length.
grpl Glottal pulse length gradient. pulse length = conts + grpl / ms. Where ms is the mark/space ratio.
xscale Scale factor for excitation both voiced and unvoiced to give output range.
foi Fundamental frequency of a typical single impulse excitation. Used to scale power of unvoiced excitation.
gclf Gain control for the low frequency formant. Such that if F1 is 500Hz its gain will be equal to the higher formants.
sil In a single impulse excitation a period of noise is replaced by a single impulse of equivalent power. This is the length of that period in milliseconds.
gouv Glottal area for unvoiced conditions.
isqthr Frequency maintanance threshold accross frames (in control values).
lsqthr As isqthr for silent formants.
ictlof Integer control offsets. Used to modify control values individually.
flflim->fmgain These are all formant parameters in the order F1, F2, F3, FHF, FHFUV, FN.
flflim Formant low frequency limits in Hz.
fincrm Formant frequency steps in Hz.
bdwtab Formant fixed bandwidths in Hz.
bdwmod Formant bandwidth modifications in Hz.
bdwnas As bdwmod but for nasals.
fqmod Formant frequency modifications.
dvoffs Offsets for voiced /unvoiced mixing for each formant.
fmgain Individual gain for each formant.
ifrecl->ipocl Clamping limits, if exceded formant clamping occurs. All are measured in control parameter steps.
ifrecl Limit of frequency change.
iampcl Limit of amplitude change.
ipocl Fundamental period limit.
alfcon If set to -1 F1 is removed from FN, if 0 it has no effect.
expat List of integers specifying the glottal pulse shape. Values in the range -127 to +127.
gapat list of integers specifying the glottal area. Values in the range 0 to 15 where 15 means fully open.