/sflib/x example  soundfile "twarp4" is a linear mix of two soundfiles,
produced by ECMC PVC examples "twarp4-1" and "twarp4-2."

twarp4-1:
 The first 1.05 seconds of the analysis file is read forwards
 and backwards, following the shape of the first half of a sine wave:
 gen5 -L1000 .5 1. 0 | reshape -M1.05  > /$SFDIR/f1
 time_point=/$SFDIR/f1      # int, float or FUNC
 lower_time_boundary=$SFDIR/f1   # int, float or FUNC
 upper_time_boundary=$SFDIR/f1   # int, float or FUNC

 The output duration is increased to 5.82:
 duration=5.84   # CHANGE the 0 to the desired output duration.

 The analysis is read at 1/2 the original speed:
 rate_multiplier=.5    # int, float or FUNC

 The pitch is transposed down a major 7th:
  pitch_transposition_in_semitones=-11  # int, float or FUNC

 But 80 herz is added to all frequencies:
 frequency_shift=80    # int, float or FUNC

 The output gain is increased to compensate for amplitude attenuation
 resulting from the processing:
 gain_in_decibels=9    # int, float or FUNC
 -  -  -
 "twarp4-2" is identical to example "twarp4," but
 also includes EQ parameters to add 12 dB of gain to frequencies 800 hz
 and above, and to attentuate frequencies below 100 hz by 12 dB
 FILTER_LOW_SHELF_EQ_gain_in_decibels=-12 
 FILTER_LOW_SHELF_EQ_frequency=100
 FILTER_HIGH_SHELF_EQ_gain_in_decibels=12 
 FILTER_HIGH_SHELF_EQ_frequency=800
 -  -  - 
To see the source files for "twarp4-1" or "twarp4-2" type
   pvcex  twarp4-1
   pvcex  twarp4-2 
