diff tools/fft.c @ 0:5242703e91d3 tip

Initial checkin for AIM92 aimR8.2 (last updated May 1997).

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/fft.c	Fri May 20 15:19:45 2011 +0100
@@ -0,0 +1,298 @@
+/*
+  FFT program adapted from routines given in Numerical Recipes.
+
+  The output framewidth = ( input framewidth + padding ) / 2  spectral points.
+
+  Padding with zeroes is recommended to counter end-effects (See NR, p416).
+  It is also necessary since framewidth + padding must be a power of 2
+  (sample points at given rate).
+  This is because the fft method is "radix-2", and because the output is
+  symmetrical so that just half the points are unique.
+  Therefore each input frame is padded with zeroes to the next power of 2
+  larger than the input framewidth.
+
+  If necessary, extra padding can be enforced using the padding option to
+  add extra zeroes, padding to a larger power of 2.
+  The amount of extra padding is "exponential", expanding the basic size to:
+	( framewidth + padding ) * 2**n
+  where the padding option is n.
+  (n=0 by default, so that no extra padding is added. When n=1 then padding is
+  added to double the size, and when n=2 the size is quadrupled, etc.).
+
+  Frames are selected from the input stream using the "frames" option,
+  which has syntax: [[-]frame=a[-b]]. Input frames  are numbered 1,2,...
+  For example:
+    frame=a      Select just the a'th frame.
+    frame=a-b    Select frames from the a'th to b'th inclusive.
+  The strings "min" and "max" can be used as specifiers, meaning eg:
+    frame=min    Select the first frame.
+    frame=max    Select the last frame.
+    frame=a-max  Select frames from the a'th to the last inclusive.
+    frame=min-b  Select frames from the first to the b'th inclusive.
+  The default selects all frames, (ie frame=min-max).
+
+  Several forms of fft processing are provided, according to the "spectrum"
+  option:  log/magnitude/phase/complex/inverse/verbose.
+
+  Log and magnitude are both magnitude spectra (log is log10 of magnitude).
+  Phase is the phase spectrum.
+  Complex is the full complex spectrum, in <real,imag> pairs.
+  Inverse transform reads framewidth numbers which are interpreted as
+  <real,imag> pairs, (ie framewidth/2 complex numbers),
+  and outputs the inverse transform scaled by 1/framewidth.
+  Verbose prints the spectrum in ASCII on the stdout.
+
+
+  Examples:
+
+1. To print the input and output frame sizes in sample points, eg for a
+   subsequent plotting program, use the size option:
+
+fft ... size=on
+
+2. An fft of a waveform sampled at 10kHz, computed within a frame of 12.8ms,
+   plotting the 2nd frame in a sequence of frames with half-frame overlap.
+
+fft samp=10kHz width=12.8ms frstep=6.4ms frame=2 file | x11plot
+
+3. An animated plot of successive fft spectra of a waveform sampled at 10kHz,
+   each computed within a frame of 12.8ms, and shifted by 2 sample points.
+
+fft samp=10kHz width=12.8ms frstep=2p file | x11play -n64
+
+4. Using the complex output from fft, and inverse transform without windowing
+   to recover original input.
+
+fft samp=10kHz frame=2 spec=complex window=off file > foo
+fft samp=10kHz frame=1 spec=inverse window=off foo | x11plot
+
+*/
+
+#include <stdio.h>
+#include <math.h>
+#include "options.h"
+#include "units.h"
+#include "strmatch.h"
+#include "sigproc.h"
+
+char applic[]     = "fast Fourier transform of contiguous frames.\n      i/p and o/p data in binary shorts." ;
+
+static char *helpstr, *debugstr, *sampstr, *widthstr, *padstr, *wstr, *sstr, *sizestr ;
+static char *startstr, *shiftstr, *framestr, *smagstr, *slogstr, *sphasestr, *echostr ;
+
+static Options option[] = {
+    {   "help"      ,   "off"       ,  &helpstr     ,   "help"                                          , DEBUG   },
+    {   "debug"     ,   "off"       ,  &debugstr    ,   "debugging switch"                              , DEBUG   },
+    {   "samplerate",   "20kHz"     ,  &sampstr     ,   "samplerate "                                   , VAL     },
+    {   "start"     ,   "0"         ,  &startstr    ,   "Start point in i/p file."                      , VAL     },
+    {   "frames"    ,   "1-max"     ,  &framestr    ,   "Select frames inclusively"                     , VAL     },
+    {   "frstep"    ,   "16ms"      ,  &shiftstr    ,   "Step between input frames."                    , VAL     },
+    {   "width"     ,   "32ms"      ,  &widthstr    ,   "Width of input frames."                        , VAL     },
+    {   "padding"   ,   "0"         ,  &padstr      ,   "Exponential frame padding"                     , SVAL    },
+    {   "window"    ,   "on"        ,  &wstr        ,   "Hamming window"                                , SETFLAG },
+    {   "spectrum"  ,   "magnitude" ,  &sstr        ,   "log/magnitude/phase/complex/inverse/verbose"   , SETFLAG },
+    {   "scalemag"  ,   "0.08"      ,  &smagstr     ,   "scale magnitude  spectrum"                     , SVAL    },
+    {   "scalelog"  ,   "10"        ,  &slogstr     ,   "scale log  spectrum"                           , SVAL    },
+    {   "scalephase",   "100"       ,  &sphasestr   ,   "scale phase spectrum"                          , SVAL    },
+    {   "size"      ,   "off"       ,  &sizestr     ,   "print input/output frame size in samples"      , SETFLAG },
+    {   "echo"      ,   "off"       ,  &echostr     ,   "echo buffered input without processing"        , SVAL    },
+   ( char * ) 0 } ;
+
+
+int     samplerate  ;
+int     width       ;
+int     step        ;
+int     zeroes      ;
+int     dowindow    ;
+double  scale       ;
+int     echo        ;
+
+float  *vec, *window ;
+short  *obuf ;
+
+int     allbins  ;
+int     halfbins ;
+
+#define MAG     1       /* magnitude spectrum */
+#define PHASE   2       /* phase spectrum     */
+#define INV     3       /* inverse transform  */
+#define VERB    4       /* verbose (ASCII)    */
+#define LOG     5       /* log magnitude      */
+#define COMP    6       /* complex spectrum   */
+
+int     output ;
+
+main (argc, argv)
+int     argc;
+char  **argv;
+{
+    FILE     *fp  ;
+    short    *buf ;
+    int       a, b ;
+    int       isign ;
+
+    fp = openopts( option,argc,argv ) ;
+    if ( !isoff( helpstr ) )
+	helpopts( helpstr, argv[0], applic, option ) ;
+
+    samplerate = to_Hz( sampstr ) ;
+    dowindow   = ison( wstr ) ;
+    echo       = ison( echostr ) ;
+    width      = to_p( widthstr, samplerate )  ;
+    step       = to_p( shiftstr, samplerate )  ;
+    zeroes     = ( getpower( width ) << atoi( padstr ) ) - width ;
+
+    allbins    = width + zeroes ;
+    halfbins   = allbins / 2    ;
+
+    if ( iststr( sstr, "magnitude" ) )  {
+	output = MAG ;
+	scale = atof( smagstr ) ;
+	isign = 1 ;
+    }
+    else if ( iststr( sstr, "log" ) )  {
+	output = LOG ;
+	scale = atof( slogstr ) ;
+	isign = 1 ;
+    }
+    else if ( iststr( sstr, "phase" ) ) {
+	output = PHASE ;
+	scale = atof( sphasestr ) ;
+	isign = 1 ;
+    }
+    else if ( iststr( sstr, "complex" ) ) {
+	output = COMP ;
+	isign = 1 ;
+    }
+    else if ( iststr( sstr, "inverse" ) ) {
+	output = INV ;
+	scale = 1./(double)width ;
+	isign = (-1) ;
+    }
+    else if ( iststr( sstr, "verbose" ) ) {
+	output = VERB ;
+	isign = 1 ;
+    }
+    else {
+	fprintf(stderr,"unknown spectrum \n");
+	exit( 1 ) ;
+    }
+
+    /* frame size printout */
+
+    if ( ison( sizestr ) ) {
+	fprintf(stderr,"fft sizes in sample points:\n" ) ;
+	fprintf(stderr,"    input  frame size = %d  (framewidth=%d + padding=%d)\n", width+zeroes, width, zeroes ) ;
+	fprintf(stderr,"    output frame size = %d \n", (width + zeroes)/2 ) ;
+	exit( 0 ) ;
+    }
+
+    /* parse bounds on number of frames */
+
+    if ( selector( framestr, &a, &b ) == 0 ) {
+	fprintf(stderr,"fft: bad frame selector [%s]\n", framestr ) ;
+	exit( 1 ) ;
+    }
+
+    /* Allocate working space */
+
+    obuf  = (short *)malloc( halfbins * sizeof(short) ) ;
+    vec   = (float *)malloc( allbins * sizeof(float) ) ;
+    if ( dowindow )
+	window = hamming( width ) ;
+
+
+    /* Compute fft for each frame of width shorts in the input stream */
+
+    if ( seekbytes( fp, (int)( to_p( startstr, samplerate ) * sizeof(short) ) ) == 0 ) {
+	fprintf(stderr,"improper seek\n") ;
+	exit( 1 ) ;
+    }
+
+    while ( ( buf = getframe( fp, a, width, step ) ) != (short *)0  && ( a<=b || b==0 ) ) {
+	if ( echo ) fwrite( buf, sizeof(short), width, stdout ) ;
+	else process( buf, isign ) ;
+	a++ ;
+    }
+    if ( a<=b && b>0 )
+	fprintf(stderr,"warning: not enough frames for request\n");
+
+    fclose( fp ) ;
+}
+
+
+process( buf, isign )
+short *buf ;
+int    isign ;
+{
+    short *bptr     = buf ;
+    short *endptr   = buf + width ;
+    short *optr     = obuf ;
+    short *endbin   = obuf + halfbins ;
+    float *wptr     = window ;
+    float *vptr     = vec    ;
+    float *endvec   = vec + allbins ;
+
+    if ( dowindow )
+	while ( bptr < endptr )
+	    *vptr++ =  *bptr++  *  *wptr++ ;
+    else
+	while ( bptr < endptr )
+	    *vptr++ =  *bptr++ ;
+
+    while ( vptr < endvec )         /* padding */
+	*vptr++ =  0 ;
+
+    fft( vec, width+zeroes, isign ) ;
+
+    vptr = vec ;
+    switch ( output ) {
+
+	case COMP  :  while ( vptr < endvec )
+			  *optr++ = (short)( *vptr++ ) ;
+		      fwrite( obuf, sizeof(short), allbins, stdout ) ;
+		      break;
+	case PHASE :  phase( vec, allbins ) ;
+		      while ( optr < endbin )
+			  *optr++ = (short)( scale * *vptr++ ) ;
+		      fwrite( obuf, sizeof(short), halfbins, stdout ) ;
+		      break;
+	case MAG   :  mag( vec, allbins ) ;
+		      while ( optr < endbin )
+			  *optr++ = (short)( scale * *vptr++ ) ;
+		      fwrite( obuf, sizeof(short), halfbins, stdout ) ;
+		      break;
+	case LOG   :  mag( vec, allbins ) ;
+		      while ( optr < endbin )
+			  *optr++ = (short)( scale * 10 * log10(*vptr++) ) ;
+		      fwrite( obuf, sizeof(short), halfbins, stdout ) ;
+		      break;
+	case INV   :  while ( vptr < endvec )
+			  *optr++ = (short)( scale * *vptr++ ) ;
+		      fwrite( obuf, sizeof(short), allbins, stdout ) ;
+		      break;
+	case VERB  :  print_complex_spectrum( (complex *)vec, halfbins, samplerate ) ;
+		      break;
+
+    }
+}
+
+
+/*
+ Pretty-print complex k-spectrum on the stdout.
+*/
+
+print_complex_spectrum(C,k,samplerate)
+complex *C;
+int      k, samplerate;
+{
+    float res;      /* frequency resolution. */
+    int   i;
+
+    res = (float)(samplerate>>1) / (float)k;
+    for (i=0; i<k ; i++) {
+	printf ("%3d.  %6.1fHz.  Re=%9.2f  Im=%9.2f  mod=%8.2f  arg=%4.2f\n",
+		i, i*res, Re(&C[i]), Im(&C[i]), mod(&C[i]), arg(&C[i]) );
+    }
+}
+