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DEFINITIONS
This source file includes following definitions.
- fft_ref_init
- fft_ref
- imdct_ref
- mdct_ref
- frandom
- gettime
- check_diff
- help
- main
/*
* (c) 2002 Fabrice Bellard
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file libavcodec/fft-test.c
* FFT and MDCT tests.
*/
#include "dsputil.h"
#include <math.h>
#include <unistd.h>
#include <sys/time.h>
#include <stdlib.h>
#include <string.h>
#undef exit
#undef random
/* reference fft */
#define MUL16(a,b) ((a) * (b))
#define CMAC(pre, pim, are, aim, bre, bim) \
{\
pre += (MUL16(are, bre) - MUL16(aim, bim));\
pim += (MUL16(are, bim) + MUL16(bre, aim));\
}
FFTComplex *exptab;
void fft_ref_init(int nbits, int inverse)
{
int n, i;
double c1, s1, alpha;
n = 1 << nbits;
exptab = av_malloc((n / 2) * sizeof(FFTComplex));
for(i=0;i<(n/2);i++) {
alpha = 2 * M_PI * (float)i / (float)n;
c1 = cos(alpha);
s1 = sin(alpha);
if (!inverse)
s1 = -s1;
exptab[i].re = c1;
exptab[i].im = s1;
}
}
void fft_ref(FFTComplex *tabr, FFTComplex *tab, int nbits)
{
int n, i, j, k, n2;
double tmp_re, tmp_im, s, c;
FFTComplex *q;
n = 1 << nbits;
n2 = n >> 1;
for(i=0;i<n;i++) {
tmp_re = 0;
tmp_im = 0;
q = tab;
for(j=0;j<n;j++) {
k = (i * j) & (n - 1);
if (k >= n2) {
c = -exptab[k - n2].re;
s = -exptab[k - n2].im;
} else {
c = exptab[k].re;
s = exptab[k].im;
}
CMAC(tmp_re, tmp_im, c, s, q->re, q->im);
q++;
}
tabr[i].re = tmp_re;
tabr[i].im = tmp_im;
}
}
void imdct_ref(float *out, float *in, int nbits)
{
int n = 1<<nbits;
int k, i, a;
double sum, f;
for(i=0;i<n;i++) {
sum = 0;
for(k=0;k<n/2;k++) {
a = (2 * i + 1 + (n / 2)) * (2 * k + 1);
f = cos(M_PI * a / (double)(2 * n));
sum += f * in[k];
}
out[i] = -sum;
}
}
/* NOTE: no normalisation by 1 / N is done */
void mdct_ref(float *output, float *input, int nbits)
{
int n = 1<<nbits;
int k, i;
double a, s;
/* do it by hand */
for(k=0;k<n/2;k++) {
s = 0;
for(i=0;i<n;i++) {
a = (2*M_PI*(2*i+1+n/2)*(2*k+1) / (4 * n));
s += input[i] * cos(a);
}
output[k] = s;
}
}
float frandom(void)
{
return (float)((random() & 0xffff) - 32768) / 32768.0;
}
int64_t gettime(void)
{
struct timeval tv;
gettimeofday(&tv,NULL);
return (int64_t)tv.tv_sec * 1000000 + tv.tv_usec;
}
void check_diff(float *tab1, float *tab2, int n)
{
int i;
double max= 0;
double error= 0;
for(i=0;i<n;i++) {
double e= fabsf(tab1[i] - tab2[i]);
if (e >= 1e-3) {
av_log(NULL, AV_LOG_ERROR, "ERROR %d: %f %f\n",
i, tab1[i], tab2[i]);
}
error+= e*e;
if(e>max) max= e;
}
av_log(NULL, AV_LOG_INFO, "max:%f e:%g\n", max, sqrt(error)/n);
}
void help(void)
{
av_log(NULL, AV_LOG_INFO,"usage: fft-test [-h] [-s] [-i] [-n b]\n"
"-h print this help\n"
"-s speed test\n"
"-m (I)MDCT test\n"
"-i inverse transform test\n"
"-n b set the transform size to 2^b\n"
);
exit(1);
}
int main(int argc, char **argv)
{
FFTComplex *tab, *tab1, *tab_ref;
FFTSample *tab2;
int it, i, c;
int do_speed = 0;
int do_mdct = 0;
int do_inverse = 0;
FFTContext s1, *s = &s1;
MDCTContext m1, *m = &m1;
int fft_nbits, fft_size;
fft_nbits = 9;
for(;;) {
c = getopt(argc, argv, "hsimn:");
if (c == -1)
break;
switch(c) {
case 'h':
help();
break;
case 's':
do_speed = 1;
break;
case 'i':
do_inverse = 1;
break;
case 'm':
do_mdct = 1;
break;
case 'n':
fft_nbits = atoi(optarg);
break;
}
}
fft_size = 1 << fft_nbits;
tab = av_malloc(fft_size * sizeof(FFTComplex));
tab1 = av_malloc(fft_size * sizeof(FFTComplex));
tab_ref = av_malloc(fft_size * sizeof(FFTComplex));
tab2 = av_malloc(fft_size * sizeof(FFTSample));
if (do_mdct) {
if (do_inverse)
av_log(NULL, AV_LOG_INFO,"IMDCT");
else
av_log(NULL, AV_LOG_INFO,"MDCT");
ff_mdct_init(m, fft_nbits, do_inverse);
} else {
if (do_inverse)
av_log(NULL, AV_LOG_INFO,"IFFT");
else
av_log(NULL, AV_LOG_INFO,"FFT");
ff_fft_init(s, fft_nbits, do_inverse);
fft_ref_init(fft_nbits, do_inverse);
}
av_log(NULL, AV_LOG_INFO," %d test\n", fft_size);
/* generate random data */
for(i=0;i<fft_size;i++) {
tab1[i].re = frandom();
tab1[i].im = frandom();
}
/* checking result */
av_log(NULL, AV_LOG_INFO,"Checking...\n");
if (do_mdct) {
if (do_inverse) {
imdct_ref((float *)tab_ref, (float *)tab1, fft_nbits);
ff_imdct_calc(m, tab2, (float *)tab1);
check_diff((float *)tab_ref, tab2, fft_size);
} else {
mdct_ref((float *)tab_ref, (float *)tab1, fft_nbits);
ff_mdct_calc(m, tab2, (float *)tab1);
check_diff((float *)tab_ref, tab2, fft_size / 2);
}
} else {
memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
ff_fft_permute(s, tab);
ff_fft_calc(s, tab);
fft_ref(tab_ref, tab1, fft_nbits);
check_diff((float *)tab_ref, (float *)tab, fft_size * 2);
}
/* do a speed test */
if (do_speed) {
int64_t time_start, duration;
int nb_its;
av_log(NULL, AV_LOG_INFO,"Speed test...\n");
/* we measure during about 1 seconds */
nb_its = 1;
for(;;) {
time_start = gettime();
for(it=0;it<nb_its;it++) {
if (do_mdct) {
if (do_inverse) {
ff_imdct_calc(m, (float *)tab, (float *)tab1);
} else {
ff_mdct_calc(m, (float *)tab, (float *)tab1);
}
} else {
memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
ff_fft_calc(s, tab);
}
}
duration = gettime() - time_start;
if (duration >= 1000000)
break;
nb_its *= 2;
}
av_log(NULL, AV_LOG_INFO,"time: %0.1f us/transform [total time=%0.2f s its=%d]\n",
(double)duration / nb_its,
(double)duration / 1000000.0,
nb_its);
}
if (do_mdct) {
ff_mdct_end(m);
} else {
ff_fft_end(s);
}
return 0;
}