libavcodec/fft-test.c

   1 /*
   2  * (c) 2002 Fabrice Bellard
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file libavcodec/fft-test.c
  23  * FFT and MDCT tests.
  24  */
  25
  26 #include "libavutil/lfg.h"
  27 #include "dsputil.h"
  28 #include <math.h>
  29 #include <unistd.h>
  30 #include <sys/time.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33
  34 #undef exit
  35
  36 /* reference fft */
  37
  38 #define MUL16(a,b) ((a) * (b))
  39
  40 #define CMAC(pre, pim, are, aim, bre, bim) \
  41 {\
  42    pre += (MUL16(are, bre) - MUL16(aim, bim));\
  43    pim += (MUL16(are, bim) + MUL16(bre, aim));\
  44 }
  45
  46 FFTComplex *exptab;
  47
  48 static void fft_ref_init(int nbits, int inverse)
  49 {
  50     int n, i;
  51     double c1, s1, alpha;
  52
  53     n = 1 << nbits;
  54     exptab = av_malloc((n / 2) * sizeof(FFTComplex));
  55
  56     for(i=0;i<(n/2);i++) {
  57         alpha = 2 * M_PI * (float)i / (float)n;
  58         c1 = cos(alpha);
  59         s1 = sin(alpha);
  60         if (!inverse)
  61             s1 = -s1;
  62         exptab[i].re = c1;
  63         exptab[i].im = s1;
  64     }
  65 }
  66
  67 static void fft_ref(FFTComplex *tabr, FFTComplex *tab, int nbits)
  68 {
  69     int n, i, j, k, n2;
  70     double tmp_re, tmp_im, s, c;
  71     FFTComplex *q;
  72
  73     n = 1 << nbits;
  74     n2 = n >> 1;
  75     for(i=0;i<n;i++) {
  76         tmp_re = 0;
  77         tmp_im = 0;
  78         q = tab;
  79         for(j=0;j<n;j++) {
  80             k = (i * j) & (n - 1);
  81             if (k >= n2) {
  82                 c = -exptab[k - n2].re;
  83                 s = -exptab[k - n2].im;
  84             } else {
  85                 c = exptab[k].re;
  86                 s = exptab[k].im;
  87             }
  88             CMAC(tmp_re, tmp_im, c, s, q->re, q->im);
  89             q++;
  90         }
  91         tabr[i].re = tmp_re;
  92         tabr[i].im = tmp_im;
  93     }
  94 }
  95
  96 static void imdct_ref(float *out, float *in, int nbits)
  97 {
  98     int n = 1<<nbits;
  99     int k, i, a;
 100     double sum, f;
 101
 102     for(i=0;i<n;i++) {
 103         sum = 0;
 104         for(k=0;k<n/2;k++) {
 105             a = (2 * i + 1 + (n / 2)) * (2 * k + 1);
 106             f = cos(M_PI * a / (double)(2 * n));
 107             sum += f * in[k];
 108         }
 109         out[i] = -sum;
 110     }
 111 }
 112
 113 /* NOTE: no normalisation by 1 / N is done */
 114 static void mdct_ref(float *output, float *input, int nbits)
 115 {
 116     int n = 1<<nbits;
 117     int k, i;
 118     double a, s;
 119
 120     /* do it by hand */
 121     for(k=0;k<n/2;k++) {
 122         s = 0;
 123         for(i=0;i<n;i++) {
 124             a = (2*M_PI*(2*i+1+n/2)*(2*k+1) / (4 * n));
 125             s += input[i] * cos(a);
 126         }
 127         output[k] = s;
 128     }
 129 }
 130
 131
 132 static float frandom(AVLFG *prng)
 133 {
 134     return (int16_t)av_lfg_get(prng) / 32768.0;
 135 }
 136
 137 static int64_t gettime(void)
 138 {
 139     struct timeval tv;
 140     gettimeofday(&tv,NULL);
 141     return (int64_t)tv.tv_sec * 1000000 + tv.tv_usec;
 142 }
 143
 144 static void check_diff(float *tab1, float *tab2, int n, double scale)
 145 {
 146     int i;
 147     double max= 0;
 148     double error= 0;
 149
 150     for(i=0;i<n;i++) {
 151         double e= fabsf(tab1[i] - (tab2[i] / scale));
 152         if (e >= 1e-3) {
 153             av_log(NULL, AV_LOG_ERROR, "ERROR %d: %f %f\n",
 154                    i, tab1[i], tab2[i]);
 155         }
 156         error+= e*e;
 157         if(e>max) max= e;
 158     }
 159     av_log(NULL, AV_LOG_INFO, "max:%f e:%g\n", max, sqrt(error)/n);
 160 }
 161
 162
 163 static void help(void)
 164 {
 165     av_log(NULL, AV_LOG_INFO,"usage: fft-test [-h] [-s] [-i] [-n b]\n"
 166            "-h     print this help\n"
 167            "-s     speed test\n"
 168            "-m     (I)MDCT test\n"
 169            "-i     inverse transform test\n"
 170            "-n b   set the transform size to 2^b\n"
 171            "-f x   set scale factor for output data of (I)MDCT to x\n"
 172            );
 173     exit(1);
 174 }
 175
 176
 177
 178 int main(int argc, char **argv)
 179 {
 180     FFTComplex *tab, *tab1, *tab_ref;
 181     FFTSample *tab2;
 182     int it, i, c;
 183     int do_speed = 0;
 184     int do_mdct = 0;
 185     int do_inverse = 0;
 186     FFTContext s1, *s = &s1;
 187     FFTContext m1, *m = &m1;
 188     int fft_nbits, fft_size;
 189     double scale = 1.0;
 190     AVLFG prng;
 191     av_lfg_init(&prng, 1);
 192
 193     fft_nbits = 9;
 194     for(;;) {
 195         c = getopt(argc, argv, "hsimn:f:");
 196         if (c == -1)
 197             break;
 198         switch(c) {
 199         case 'h':
 200             help();
 201             break;
 202         case 's':
 203             do_speed = 1;
 204             break;
 205         case 'i':
 206             do_inverse = 1;
 207             break;
 208         case 'm':
 209             do_mdct = 1;
 210             break;
 211         case 'n':
 212             fft_nbits = atoi(optarg);
 213             break;
 214         case 'f':
 215             scale = atof(optarg);
 216             break;
 217         }
 218     }
 219
 220     fft_size = 1 << fft_nbits;
 221     tab = av_malloc(fft_size * sizeof(FFTComplex));
 222     tab1 = av_malloc(fft_size * sizeof(FFTComplex));
 223     tab_ref = av_malloc(fft_size * sizeof(FFTComplex));
 224     tab2 = av_malloc(fft_size * sizeof(FFTSample));
 225
 226     if (do_mdct) {
 227         av_log(NULL, AV_LOG_INFO,"Scale factor is set to %f\n", scale);
 228         if (do_inverse)
 229             av_log(NULL, AV_LOG_INFO,"IMDCT");
 230         else
 231             av_log(NULL, AV_LOG_INFO,"MDCT");
 232         ff_mdct_init(m, fft_nbits, do_inverse, scale);
 233     } else {
 234         if (do_inverse)
 235             av_log(NULL, AV_LOG_INFO,"IFFT");
 236         else
 237             av_log(NULL, AV_LOG_INFO,"FFT");
 238         ff_fft_init(s, fft_nbits, do_inverse);
 239         fft_ref_init(fft_nbits, do_inverse);
 240     }
 241     av_log(NULL, AV_LOG_INFO," %d test\n", fft_size);
 242
 243     /* generate random data */
 244
 245     for(i=0;i<fft_size;i++) {
 246         tab1[i].re = frandom(&prng);
 247         tab1[i].im = frandom(&prng);
 248     }
 249
 250     /* checking result */
 251     av_log(NULL, AV_LOG_INFO,"Checking...\n");
 252
 253     if (do_mdct) {
 254         if (do_inverse) {
 255             imdct_ref((float *)tab_ref, (float *)tab1, fft_nbits);
 256             ff_imdct_calc(m, tab2, (float *)tab1);
 257             check_diff((float *)tab_ref, tab2, fft_size, scale);
 258         } else {
 259             mdct_ref((float *)tab_ref, (float *)tab1, fft_nbits);
 260
 261             ff_mdct_calc(m, tab2, (float *)tab1);
 262
 263             check_diff((float *)tab_ref, tab2, fft_size / 2, scale);
 264         }
 265     } else {
 266         memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
 267         ff_fft_permute(s, tab);
 268         ff_fft_calc(s, tab);
 269
 270         fft_ref(tab_ref, tab1, fft_nbits);
 271         check_diff((float *)tab_ref, (float *)tab, fft_size * 2, 1.0);
 272     }
 273
 274     /* do a speed test */
 275
 276     if (do_speed) {
 277         int64_t time_start, duration;
 278         int nb_its;
 279
 280         av_log(NULL, AV_LOG_INFO,"Speed test...\n");
 281         /* we measure during about 1 seconds */
 282         nb_its = 1;
 283         for(;;) {
 284             time_start = gettime();
 285             for(it=0;it<nb_its;it++) {
 286                 if (do_mdct) {
 287                     if (do_inverse) {
 288                         ff_imdct_calc(m, (float *)tab, (float *)tab1);
 289                     } else {
 290                         ff_mdct_calc(m, (float *)tab, (float *)tab1);
 291                     }
 292                 } else {
 293                     memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
 294                     ff_fft_calc(s, tab);
 295                 }
 296             }
 297             duration = gettime() - time_start;
 298             if (duration >= 1000000)
 299                 break;
 300             nb_its *= 2;
 301         }
 302         av_log(NULL, AV_LOG_INFO,"time: %0.1f us/transform [total time=%0.2f s its=%d]\n",
 303                (double)duration / nb_its,
 304                (double)duration / 1000000.0,
 305                nb_its);
 306     }
 307
 308     if (do_mdct) {
 309         ff_mdct_end(m);
 310     } else {
 311         ff_fft_end(s);
 312     }
 313     return 0;
 314 }