tomwalters@0: /**************************************************************************
tomwalters@0: 
tomwalters@0: 	Filter-bank routines.
tomwalters@0:        ======================
tomwalters@0: 
tomwalters@0: Filter-bank parameters in model headers are as follows:
tomwalters@0: (These may be converted, using the given routines, into values which are then
tomwalters@0: passed as args into the routines below. All the values are double except for
tomwalters@0: the number of channels which is an int. Remember to cast Freq as double).
tomwalters@0: 
tomwalters@0: String name    Conversion   Value      Comment
tomwalters@0: -------------  -----------  ---------  -------------------------------------
tomwalters@0: channels_afb   Optionint()  channels   Number of channels in filter
tomwalters@0: mincf_afb      Freq()       mincf      Minimum center frequency (Hz)
tomwalters@0: maxcf_afb      Freq()       maxcf      Maximum center frequency (Hz)
tomwalters@0: dencf_afb      atof()       dencf      Filter density (filters/critical band)
tomwalters@0: bwmin_afb      Freq()       bwmin      Minimum filter bandwith
tomwalters@0: quality_afb    Freq()       quality    Ultimate qualtity factor of filters
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: Initialize global filter parameters.
tomwalters@0: 
tomwalters@0:     SetErbParameters( bwmin, quality )
tomwalters@0:     double bwmin, quality ;
tomwalters@0: 
tomwalters@0: Return array of centre frequencies for given density.
tomwalters@0: 
tomwalters@0:     double *GenerateCenterFrequencies( mincf, maxcf, dencf )
tomwalters@0:     double mincf, maxcf, dencf ;
tomwalters@0: 
tomwalters@0: (This uses routine GenerateScale() to compute the scale, and uses
tomwalters@0: routine ErbScale() to convert the parameters (mincf etc) into Erbs).
tomwalters@0: 
tomwalters@0: Return array of centre frequencies for given number of channels.
tomwalters@0: 
tomwalters@0:     double *NumberedCenterFrequencies( mincf, maxcf, channels )
tomwalters@0:     double mincf, maxcf ;
tomwalters@0:     int    channels ;
tomwalters@0: 
tomwalters@0: (This uses routine NumberedScale() to compute the scale, and uses
tomwalters@0: routine ErbScale() to convert the parameters (mincf etc) into Erbs).
tomwalters@0: 
tomwalters@0: Return number of channels for given density.
tomwalters@0: 
tomwalters@0:     int NumberCenterFrequencies( mincf, maxcf, dencf )
tomwalters@0:     double mincf, maxcf, dencf ;
tomwalters@0: 
tomwalters@0: Basic utilities:
tomwalters@0: 
tomwalters@0: ErbScale()      Convert freq in Hz to Erbs.
tomwalters@0: 
tomwalters@0: 
tomwalters@0: Example of application
tomwalters@0: ----------------------
tomwalters@0: 
tomwalters@0: #include "freqs.c"
tomwalters@0: 
tomwalters@0: int    channels = 0     ;
tomwalters@0: double mincf    = 220.  ;
tomwalters@0: double maxcf    = 4400. ;
tomwalters@0: double dencf    = 4.    ;
tomwalters@0: double bwmin    = 24.7  ;
tomwalters@0: double quality  = 9.265 ;
tomwalters@0: 
tomwalters@0:     SetErbParameters( bwmin, quality ) ;
tomwalters@0: 
tomwalters@0:     if (channels==0) {
tomwalters@0: 	frequencies = GenerateCenterFrequencies( mincf, maxcf, dencf ) ;
tomwalters@0: 	channels = NumberCenterFrequencies( mincf, maxcf, dencf ) ;
tomwalters@0:     }
tomwalters@0:     else
tomwalters@0: 	frequencies = NumberedCenterFrequencies( mincf, maxcf, channels ) ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0: **************************************************************************/
tomwalters@0: 
tomwalters@0: extern void SetErbParameters() ;
tomwalters@0: 
tomwalters@0: extern double Erb(), ErbScale(), FofErbScale() ;
tomwalters@0: 
tomwalters@0: extern double *GenerateCenterFrequencies() ;
tomwalters@0: extern int     NumberCenterFrequencies() ;
tomwalters@0: extern double *NumberedCenterFrequencies() ;
tomwalters@0: extern double *GenerateScale() ;
tomwalters@0: extern int     NumberOnScale() ;
tomwalters@0: extern double *NumberedScale() ;
tomwalters@0: 
tomwalters@0: /* Defaults */
tomwalters@0: 
tomwalters@0: static double limit = 24.7  ;
tomwalters@0: static double Q     = 9.265 ;
tomwalters@0: 
tomwalters@0: /**********************  filter/gamma_tone.c *******************************/
tomwalters@0: 
tomwalters@0: double bankBaseFrequency   = 1000. ;
tomwalters@0: 
tomwalters@0: double *GenerateCenterFrequencies( min_cf, max_cf, erb_density )
tomwalters@0: double min_cf, max_cf, erb_density ;
tomwalters@0: {
tomwalters@0:     return ( GenerateScale( ErbScale( min_cf ), ErbScale( max_cf ), erb_density, ErbScale( bankBaseFrequency ), FofErbScale ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: int NumberCenterFrequencies( min_cf, max_cf, erb_density )
tomwalters@0: double min_cf, max_cf, erb_density ;
tomwalters@0: {
tomwalters@0:     return ( NumberOnScale( ErbScale( min_cf ), ErbScale( max_cf ), erb_density, ErbScale( bankBaseFrequency ) ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: double *NumberedCenterFrequencies( min_cf, max_cf, channels )
tomwalters@0: double min_cf, max_cf ;
tomwalters@0: int channels ;
tomwalters@0: {
tomwalters@0:     return ( NumberedScale( ErbScale( min_cf ), ErbScale( max_cf ), channels, FofErbScale ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /********************** filter/scales.c ************************************/
tomwalters@0: 
tomwalters@0: double *GenerateScale( min, max, density, base, inverse )
tomwalters@0: double min, max, density, base, (*inverse)() ;
tomwalters@0: {
tomwalters@0:     unsigned n_scale = NumberOnScale( min, max, density, base ) ;
tomwalters@0:     double *scale ;
tomwalters@0:     double scale_start ;
tomwalters@0:     int i ;
tomwalters@0: 
tomwalters@0:     scale = (double *)malloc( (n_scale+1) * sizeof(double) ) ;
tomwalters@0: 
tomwalters@0:     if( min != max ) {
tomwalters@0: 
tomwalters@0: 	scale_start = base - floor( ( base - min ) * density ) / density ;
tomwalters@0: 
tomwalters@0: 	/* fill array scale points 1./density apart */
tomwalters@0: 
tomwalters@0: 	for( i=0 ; i < n_scale  ; i++ )
tomwalters@0: 	    scale[ i ] = scale_start + i / density   ;
tomwalters@0: 
tomwalters@0: 	scale[ i++ ] = 0. ;
tomwalters@0:     }
tomwalters@0:     else {
tomwalters@0: 	scale[0] = min ;
tomwalters@0: 	scale[1] = 0.  ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0: 	/* convert scale space back to units required */
tomwalters@0: 
tomwalters@0:     if( inverse != (double ( * )()) 0 )
tomwalters@0: 	for( i=0 ; i < n_scale  ; i++ )
tomwalters@0: 	    scale[ i ] = inverse( scale[ i ] ) ;
tomwalters@0: 
tomwalters@0:     return ( scale ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: int NumberOnScale( min, max, density, base )
tomwalters@0: double min, max, density, base ;
tomwalters@0: {
tomwalters@0:     if( min != max )
tomwalters@0: 	return ( ( int ) ( ( floor( ( base - min ) * density ) + 1. + ( floor( ( max - base ) * density ) ) ) ) ) ;
tomwalters@0:     else
tomwalters@0: 	return ( 1 ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: double *NumberedScale( min, max, channels, inverse )
tomwalters@0: double min, max ;
tomwalters@0: int channels ;
tomwalters@0: double (*inverse)() ;
tomwalters@0: {
tomwalters@0:     double *scale ;
tomwalters@0:     int chan ;
tomwalters@0: 
tomwalters@0:     scale = (double *)malloc( (channels+1) * sizeof(double) ) ;
tomwalters@0: 
tomwalters@0:     scale[ 0 ] = min ;
tomwalters@0:     for( chan=1 ; chan < channels  ; chan++ )
tomwalters@0: 	scale[ chan ] = min + chan * (max-min) / ( channels - 1 ) ;
tomwalters@0: 
tomwalters@0:     if( inverse != (double ( * )()) 0 )
tomwalters@0: 	for( chan=0 ; chan < channels  ; chan++ )
tomwalters@0: 	    scale[ chan ] = inverse( scale[ chan ] ) ;
tomwalters@0: 
tomwalters@0:     scale[ channels ] = 0. ;
tomwalters@0: 
tomwalters@0:     return ( scale ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: /********************** filter/formulae.c ************************************/
tomwalters@0: 
tomwalters@0: 
tomwalters@0: void SetErbParameters( new_limit, new_Q )
tomwalters@0: double new_limit, new_Q ;
tomwalters@0: {
tomwalters@0:     limit = new_limit ;
tomwalters@0:     Q     = new_Q     ;
tomwalters@0: 
tomwalters@0:     return ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: double ErbScale( frequency )
tomwalters@0: 	  double frequency ;
tomwalters@0: {
tomwalters@0:     return ( log( 1. + frequency / Q / limit ) * Q ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: double FofErbScale( E )
tomwalters@0: 	     double E ;
tomwalters@0: {
tomwalters@0:     return ( ( exp( E / Q ) - 1 ) * Q * limit ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: